Free rep range converter
Rep Range to 1RM Converter
You lift a weight for a few reps. You want to know what that means: what percentage of your one rep max is it, and what is your estimated 1RM? Put your set into the converter and you get both answers in seconds — no max test needed.
- Reps to % of 1RM
- Weight to estimated 1RM
- % of 1RM to reps
- 1 to 20 rep chart
This page gives you estimates, not a measured max. Use them to plan training, not to load a weight you have never handled safely.
Rep Range to 1RM Converter
Compare estimated percentages and training loads from a completed working set.
60 seconds
How to Use the Rep Range to 1RM Converter
You need only two numbers to start: the weight you lifted and the reps you finished with good form. The converter does the rest, and this page shows you how to read the result and how to use it in your next session.
Enter Your Set
Type in the weight and the reps from one hard set. Count only full reps you finished with good form. A half rep, a spotted rep, or a rep where your form broke down does not count.
Read Your Percentage
You get the percentage of 1RM that set represents. If you did 8 reps, you were near 81%. If you did 5 reps, you were near 87%. That percentage tells you how heavy the set really was.
Get Your Estimated 1RM
You also get an estimated 1RM. If you lifted 100 kg for 8 reps, your estimated 1RM is about 123.5 kg. Use that number to set your next training weights.
Turn It Back Into Training
Work backwards from the estimate. Want a 5-rep set? Take about 87% of your estimated 1RM. Want a 10-rep set? Take about 77%. Round to plates you can actually load.
What Your Rep Range Tells You About Your 1RM
Every rep range sits at a different percentage of your maximum. One rep is your 100%. As you add reps, the weight you can handle falls, because fatigue builds and your muscles cannot produce the same force for as long. That fall is predictable enough to estimate from, but it is not identical for every person or every lift.
Think of it this way: if you can lift a weight for only 3 reps, that weight is close to your max. If you can lift a weight for 20 reps, that weight is far from your max. The converter turns that simple idea into a number you can train with.
You should treat every result on this page as a starting estimate. Your real max depends on your technique, your fatigue on the day, the lift, and how used you are to high or low reps. That is why this page gives you a range, a chart, and a way to check the estimate against your next session — not just one magic number.
The Rep Range to 1RM Percentage Chart: 1 to 20 Reps
Use this chart when you want a quick answer without the tool. Find your reps on the left, read the percentage calculate in the middle, and multiply that percentage by your estimated 1RM to get a training weight — or divide a weight you lifted by that percentage to estimate your 1RM.
| Reps | % of 1RM | What It Usually Means |
|---|---|---|
| 1 | 100% | True max effort |
| 2 | 95% | Heavy strength |
| 3 | 93% | Heavy strength |
| 4 | 90% | Strength |
| 5 | 87% | Strength |
| 6 | 85% | Strength |
| 7 | 83% | Strength and size |
| 8 | 81% | Strength and size |
| 9 | 79% | Strength and size |
| 10 | 77% | Strength and size |
| 11 | 75% | Muscle size |
| 12 | 73% | Muscle size |
| 13 | 71% | Muscular endurance |
| 14 | 70% | Muscular endurance |
| 15 | 68% | Muscular endurance |
| 16 | 67% | Muscular endurance |
| 17 | 65% | Muscular endurance |
| 18 | 64% | Muscular endurance |
| 19 | 63% | Muscular endurance |
| 20 | 61% | Muscular endurance |
The Answers People Search For Most
What percentage of your 1RM is 8 reps? About 81%. What percentage of your 1RM is 5 reps? About 87%. What percentage of your 1RM is 10 reps? About 77%. What percentage of your 1RM is 12 reps? About 73%. What percentage of your 1RM is 15 reps? About 68%. What percentage of your 1RM is 20 reps? About 61%.
Notice how the gaps get smaller as reps rise. The jump from 1 to 5 reps covers 13 percentage points. The jump from 15 to 20 reps covers only 7 points. That is one reason high-rep estimates are less precise: a small error in reps, or in how hard the set felt, moves your estimated 1RM by a lot.
Worked Examples You Can Check Yourself
Every example below uses the chart above, so you can check the math in seconds. Estimated 1RM = weight lifted ÷ percentage. For example, 100 ÷ 0.81 = 123.5.
| Set You Lifted | Chart % | Estimated 1RM | What It Means |
|---|---|---|---|
| 100 kg × 8 reps | 81% | 123.5 kg | A solid strength-and-size set. |
| 120 kg × 5 reps | 87% | 137.9 kg | A heavy strength set, close to your max. |
| 80 kg × 10 reps | 77% | 103.9 kg | A typical size-focused set. |
| 60 kg × 12 reps | 73% | 82.2 kg | A size set at the top of the hypertrophy range. |
| 140 kg × 3 reps | 93% | 150.5 kg | A near-max set. Treat it as a strong estimate, not a tested max. |
| 50 kg × 20 reps | 61% | 82.0 kg | Use this one with care — high-rep estimates are the least accurate. |
Turn an Estimated 1RM Back Into a Training Weight
If your estimated 1RM is 140 kg, your training weights from the same chart are: 3 reps at about 130.2 kg, 5 reps at about 121.8 kg, 8 reps at about 113.4 kg, 10 reps at about 107.8 kg, 12 reps at about 102.2 kg, 15 reps at about 95.2 kg, and 20 reps at about 85.4 kg. You calculate each one the same way: 1RM × percentage ÷ 100. For 8 reps that is 140 × 81 ÷ 100 = 113.4 kg.
Round the result to plates you can build. 113.4 kg becomes 112.5 kg or 115 kg in most gyms. A perfect number on paper is useless if you cannot load it safely.
Reps to Percentage of 1RM
Find your reps in the chart. You do not need to know your 1RM for this direction. 8 reps means about 81%, whatever your max is.
Weight and Reps to 1RM
Estimated 1RM = weight ÷ percentage. You lifted 100 kg for 8 reps, so you divide 100 by 0.81 and you get about 123.5 kg.
Percentage to Reps and Weight
Training weight = 1RM × percentage ÷ 100. You want a 10-rep set from a 140 kg max, so you take 77% and you get about 107.8 kg.
Convert Reps to Percentage, Percentage to Reps, and Sets to 1RM
Most converters only go one way. You usually need all three, and they answer different questions in training. You ask “how heavy was that set?” when you convert reps to a percentage. You ask “what is my max?” when you back-calculate your 1RM from reps and weight. You ask “what should I load today?” when you convert a percentage back to a weight. Keep the direction clear, and you will not mix up a rep-max weight with a working-set weight — a mistake this page returns to below, because it is common and costly.
The 7 Formulas Behind a 1RM Estimate, Compared
No single formula owns the truth. Each one was built from different lifters, lifts, and rep ranges, so each one gives you a slightly different answer from the same set. That is why many converters, including the idea behind an average 1RM formula calculator, show you several formulas at once and then average them.
Here is what each formula gives you for the same set: 100 kg for 8 reps. In the formulas, w is the weight you lifted and r is the reps you finished.
| Formula | How You Calculate 1RM | Result for 100 kg × 8 |
|---|---|---|
| Epley | w × (1 + r ÷ 30) | 126.7 kg |
| Brzycki | w × 36 ÷ (37 − r) | 124.1 kg |
| Lander | 100w ÷ (101.3 − 2.67123r) | 125.1 kg |
| Lombardi | w × r ^ 0.10 | 123.1 kg |
| Mayhew | 100w ÷ (52.2 + 41.9e ^ (−0.055r)) | 126.3 kg |
| O’Conner | w × (1 + r ÷ 40) | 120.0 kg |
| Wathan | 100w ÷ (48.8 + 53.8e ^ (−0.075r)) | 127.7 kg |
| Average of all 7 | Add the 7 results and divide by 7 | 124.7 kg |
The range here is 120.0 kg to 127.7 kg — a spread of 7.7 kg from one set. The chart on this page gives 123.5 kg for the same set, which sits inside that range and near the average of 124.7 kg. Use the average when you want one number, but keep the range in mind when you choose a training weight. If the range is wide, choose the lower end for your first session with the new number.
Epley or Brzycki: Which One Should You Trust?
You do not have to pick a winner. Epley tends to run a little high at higher reps, Brzycki tends to fall faster as reps rise, and O’Conner tends to run low in this example. If two formulas agree closely, you can trust the estimate more. If they disagree by a lot, your set was probably at a rep count, or on a lift, where estimates are weak — usually above 12 reps, or on a lift you rarely train at that rep range.
1RM Training Zones by Rep Range
Zones overlap, and that overlap is honest. A 6-rep set can build both strength and size. A 12-rep set can build size and endurance. Use the zones to choose a direction, not to draw a hard wall between goals.
1 to 3 Reps: 93% to 100%
Maximal strength and powerlifting practice. You work with very heavy weights, few reps, and long rests. You need a spotter or safety bars, and you should not chase a true max every week.
4 to 6 Reps: 85% to 90%
Heavy strength. This is where many lifters build their base for a bigger max. Sets stay short, form must stay tight, and fatigue builds fast.
6 to 12 Reps: 73% to 85%
Muscle size, with strength as a bonus. This is the classic hypertrophy rep range. You can accumulate more total work here than at 90% and above, without the same joint and nervous-system cost.
13 to 20 Reps: 61% to 71%
Muscular endurance and work capacity. You build the ability to keep producing force when you are tired. Do not use this range as your main max estimator — see the accuracy section below.
Best Rep Range for Strength, Hypertrophy, and Endurance
Your goal does not change the chart, but it changes which part of the chart you live in most of the time.
| Your Goal | Rep Range | % of 1RM | A Sensible Starting Point |
|---|---|---|---|
| Maximal strength | 1–6 reps | 85%–100% | 3–5 sets, long rests, technique first. |
| Powerlifting | 1–5 reps, with 6–12 rep assistance work | 87%–100% for main lifts | Heavy main lift first, lighter assistance after. |
| Muscle hypertrophy | 6–12 reps | 73%–85% | 3–4 sets per exercise, close to failure on the last set, not every set. |
| Muscular endurance | 13–20 reps | 61%–71% | 2–3 sets, shorter rests, form must not collapse. |
You can build muscle outside 6–12 reps, and you can build strength outside 1–6 reps. The ranges above are where most of your work should sit for that goal, not the only reps that ever work. If you only ever train at 20 reps, your max will still rise a little, but it will not rise as fast as if you also spent time at 3–6 reps.
How Accurate Is a 1RM Estimate by Rep Count?
Accuracy is not the same at every rep count. Short, hard sets predict a max well. Long sets predict it poorly, because other things start to limit you before pure strength does.
| Reps You Used | Accuracy | Why |
|---|---|---|
| 1–2 | High if it was a true test, risky as a test | You are measuring the max itself, but a bad day or a technique slip changes the result a lot. |
| 3–5 | Best balance of safety and accuracy | You are close to your max, but you do not have to test it directly. |
| 6–10 | Good | Still close enough to your max that strength, not endurance, is the main limit. |
| 11–12 | Usable, but the range widens | Fatigue and technique start to matter more, and formulas start to disagree. |
| 13–20 | Weak — use only as a rough guide | Cardio, local endurance, and form breakdown can stop you long before strength does. |
High-rep accuracy also depends on the lift. A leg press set of 20 reps tells you less about your squat max than a squat set of 20 reps tells you about itself, and a machine set tells you less about a free-weight max than a free-weight set does. When you must estimate from high reps, use the lower end of the formula range, and retest with a shorter set before you plan a heavy block around the number.
Why Different Calculators Give You Different Numbers
You enter the same set into two calculators and you get two different 1RMs. That does not mean one of them is broken. They may use different formulas, different rounding, or a different chart. One may use Epley alone, another may average seven formulas, and a third may use a chart built from powerlifters only. If the difference is 2–3 kg, ignore it and round to plates. If the difference is 10 kg or more, check the rep count you entered first, then check whether the calculator was built for your lift and your experience level.
Can You Use This Converter If You Do Not Know Your 1RM?
Yes — that is exactly the point. You do not need a max to start. You need one recent hard set.
Pick a weight you can lift for 3 to 10 reps with good form, and take the set close to failure, but stop before your form breaks. Record the weight and the reps. Put them into the converter. You now have an estimated 1RM, and you can use the chart above to turn that estimate into training weights for any rep range.
Do not start with a 20-rep set for this job if you can avoid it. A 5-rep or 8-rep set gives you a tighter estimate. Do not use a set from months ago either. Your estimate is only as current as the set you base it on. If you have got stronger since that set, your estimate will be low. If you are tired, detrained, or coming back from a break, it will be high.
How to Turn a Rep Range Into a Training Plan
A rep-max percentage is not a working-set weight. This distinction matters more than any single number on this page. If your 8-rep max is 81% of your 1RM, you cannot do five sets of 8 reps at 81%. You would fail long before the last set. For volume work, you leave reps in reserve: you use a lighter percentage than the rep-max percentage, or you stop a rep or two short of failure.
A simple progression rule works well for most lifters: when you can finish all your planned sets and reps at the top of your target range with good form, add a small amount of weight next session — 2.5 kg on upper-body lifts, 5 kg on lower-body lifts, or the smallest plate jump your gym allows. When you cannot finish the bottom of the range, keep the weight the same and build reps first.
| Day | Focus | Example From a 123.5 kg Estimated 1RM |
|---|---|---|
| Monday | Strength | 4 sets × 4 reps at about 85% — about 105 kg. Your 4-rep max is 90%, so you leave room for four sets. |
| Wednesday | Hypertrophy | 3 sets × 10 reps at about 70% — about 86.5 kg. Your 10-rep max is 77%, so you leave room for three sets. |
| Friday | Endurance and technique | 3 sets × 15 reps at about 60% — about 74 kg. Your 15-rep max is 68%, so the sets stay clean. |
Retest, or re-estimate, every 4 to 8 weeks, or sooner if your top-range sets suddenly feel easy. If you add weight every week, your old estimate is already out of date. If you miss reps for two sessions in a row, do not force the same weights — check your sleep, stress, and recovery first, then re-estimate from a fresh hard set.
Round to Plates You Can Load
After you convert, round to your smallest plate jump. In kg gyms that is often 2.5 kg total, or 1.25 kg per side. In lb gyms it is often 5 lb total, or 2.5 lb per side. If your gym has fractional plates, you can stay closer to the exact number. Always include the bar in the total — a 20 kg bar, or a 45 lb bar, is part of the weight, not extra.
Keep kg and lb Separate
Do not mix units in one calculation. If your 1RM is in kg, your training weights must be in kg. If you switch gyms and the new gym uses lb, convert the whole plan at once: multiply kg by 2.205 to get lb, and round again to plates. A mixed plan is how a 100 kg set quietly becomes a 100 lb set, or worse, the other way round.
Check the Estimate With RPE
If your chart says 8 reps should be 81%, but your 8-rep set felt like you had 3 reps left, your true percentage for that set was lower — you were not at your 8-rep max. If it felt like a true max and you could not do a ninth rep, the chart fits. Use that feel as a cross-check, not as a replacement for the number.
Common Mistakes That Break a Rep Range Conversion
- Counting failed or spotted reps. Only count reps you finished yourself, with full range and good form.
- Using a rep-max weight for every set. A weight you can do once for 8 reps is not a weight you can do for five sets of 8.
- Copying a percentage from another lift. Your bench, squat, and deadlift do not share one max, and neither do free weights and machines.
- Using an old set. A set from three months ago does not describe your strength today.
- Testing a true 1RM too often. You do not need a tested max to train well. An estimate from a 3- to 10-rep set is safer and usually enough.
- Forgetting the bar. Plates alone are not the total weight. Add the bar every time.
A Short Safety Note
Do not test a true 1RM alone on a lift where you can get pinned — bench press without a spotter or safety bars is the classic example. Use an estimated 1RM from a submaximal set instead, and keep heavy singles for sessions where you have a spotter, safety bars, and a clear plan to bail safely. If your form breaks down, the set is over, even if the chart says you had reps left.
Track Your Estimates So They Stay Honest
Write down the set, not just the result. A 1RM number without the set behind it is hard to trust a month later.
| Date | Lift | Weight × Reps | Chart % | Estimated 1RM | Notes |
|---|---|---|---|---|---|
| — | Squat | 100 kg × 8 | 81% | 123.5 kg | Form stayed tight, last rep was hard. |
| — | Bench press | 80 kg × 10 | 77% | 103.9 kg | Touch-and-go, not paused. |
| — | Deadlift | 140 kg × 3 | 93% | 150.5 kg | Straps on, belt on — note it, or the next estimate will not match. |
Troubleshooting: When the Number Looks Wrong
| Problem | Likely Cause | What You Do |
|---|---|---|
| Estimated 1RM is far above what you can actually lift | High-rep set, or a set with help / partial reps | Re-estimate from a 3- to 10-rep set with strict form, and use the lower end of the range. |
| Two calculators disagree by a lot | Different formulas, or a high rep count | Check the rep count first, then compare the formula range in the table above. |
| Your new training weights feel far too easy | You got stronger, or your first set was not hard | Add weight by the progression rule above, and re-estimate from a fresh hard set. |
| Your new training weights feel impossible | You are tired, detrained, or the first set was a lifetime best | Keep the weights, build reps, and re-estimate after a normal week — do not force a max. |
81%
of your 1RM is about what 8 reps represents.
87%
of your 1RM is about what 5 reps represents.
124.7 kg
is the 7-formula average for 100 kg × 8 reps.
Rep Range to 1RM Converter: Frequently Asked Questions
What percentage of my 1RM is 8 reps?
About 81%. If your 1RM is 140 kg, an 8-rep set sits near 113.4 kg. That is the weight you could lift for about 8 good reps in one all-out set, not a weight you should expect to repeat for five sets of 8.
What percentage of my 1RM is 5 reps?
About 87%. If your 1RM is 140 kg, a 5-rep set sits near 121.8 kg. Five reps is a strong strength set, close to your max, so keep your form tight and your rests long.
What percentage of my 1RM is 10 reps?
About 77%. If your 1RM is 140 kg, a 10-rep set sits near 107.8 kg. Ten reps sits in the strength-and-size zone, and it is a useful set for estimating a max without testing one directly.
What percentage of my 1RM is 12 reps?
About 73%. If your 1RM is 140 kg, a 12-rep set sits near 102.2 kg. Twelve reps is at the top of the classic size range, and estimates from here are still usable, but the range starts to widen.
What percentage of my 1RM is 15 reps?
About 68%. If your 1RM is 140 kg, a 15-rep set sits near 95.2 kg. Fifteen reps is endurance work, and an estimate from this range is rough — use it as a guide, not as a precise max.
What percentage of my 1RM is 20 reps?
About 61%. If your 1RM is 140 kg, a 20-rep set sits near 85.4 kg. Twenty reps tells you about endurance and work capacity, and it is the weakest range on this page for estimating a max.
How do I convert reps to a percentage of 1RM?
Find your reps in the chart on this page and read across to the percentage. You do not need to know your 1RM for this step. If you do know it, multiply it by that percentage and divide by 100 to get the weight for that rep range.
Can I use this converter if I do not know my 1RM?
Yes. Take one recent hard set of 3 to 10 reps with good form, enter the weight and reps, and the converter estimates your 1RM for you. That estimate then lets you work out training weights for any other rep range.
What is the best rep range for building strength?
Most of your strength work should sit at 1 to 6 reps, which is about 85% to 100% of your 1RM. You do not need to live at 1 rep to get stronger — 3 to 6 reps gives you heavy work with more total sets and less testing risk.
What is the best rep range for muscle hypertrophy?
Most of your size work should sit at 6 to 12 reps, which is about 73% to 85% of your 1RM. You can build muscle outside that range too, but this range lets you accumulate a lot of hard, clean work without the recovery cost of constant near-max lifting.
What is the best rep range for muscular endurance?
Most endurance work should sit at 13 to 20 reps, which is about 61% to 71% of your 1RM. Keep your form clean and your rests shorter than you would use for strength work, and stop the set if your form collapses.
How accurate is a 1RM estimate from high reps?
It gets weaker as reps rise. Estimates from 3 to 10 reps are usually good. Estimates from 11 to 12 reps are usable but wider. Estimates from 13 to 20 reps are rough, because cardio, local endurance, and technique can stop you before strength does.
Which formula is best: Epley or Brzycki?
Neither one wins on its own. For 100 kg for 8 reps, Epley gives 126.7 kg and Brzycki gives 124.1 kg. If the formulas agree closely, trust the estimate more. If they disagree a lot, use the average and the lower end for your first session, and re-estimate from a shorter set.
Why do different calculators give different 1RM numbers?
They use different formulas, different charts, or different rounding. One may use Epley alone, another may average seven formulas, and a third may use data from one type of lifter only. A difference of 2 to 3 kg is rounding. A difference of 10 kg or more usually means a high rep count, or a set that was not a true hard set.
Can I convert a percentage back to reps?
Yes, and you should. Read the chart backwards: 87% points to about 5 reps, 81% points to about 8 reps, and 77% points to about 10 reps. That reverse reading is how you turn a program percentage into a set you can actually do.
Does the same rep range mean the same percentage on every lift?
No. Your squat, bench press, deadlift, and machine lifts do not share one curve. Technique, range of motion, and how much a lift taxes your whole body all change the result. Estimate each lift from its own recent sets, and do not copy a percentage from one lift to another.
Should I count reps I did not finish?
No. Count only full reps you finished yourself with good form. A spotted rep, a half rep, or a rep where your form broke down does not belong in the calculation, because it makes your estimated 1RM look higher than it really is.
How often should I update my estimated 1RM?
Re-estimate every 4 to 8 weeks, or sooner if your top-range sets suddenly feel easy. If you are adding weight every week, your old estimate is already out of date. If you miss reps for two sessions in a row, check recovery first, then re-estimate from a fresh set.
Is 1 rep really 100% of my 1RM?
By definition, yes: your 1RM is the most you can lift once with good form. In practice, a tested 1RM on a good day and an estimated 1RM from a submaximal set will differ by a few kilograms, because fatigue, technique, and the day itself all matter.
Can I use this converter for powerlifting?
Yes, with one caution. Powerlifters live mostly at 1 to 5 reps for main lifts, and they use lighter assistance work at 6 to 12 reps. Use the converter for both, but keep competition lifts strict — paused bench, squat depth, and deadlift lockout — or your estimate will not match a competition max.