One-Rep Max Calculator
Estimate your one-rep max from a set you have already done, and see training weights for every rep range.
How do I calculate my one-rep max?
Enter a weight and the reps you did with good form. The calculator averages the Epley and Brzycki formulas. For example, 185 lb for 5 reps ≈ 212 lb 1RM, and 100 kg for 5 reps ≈ 115 kg. It works for bench press, squat, deadlift and other barbell lifts.
How to use the 1RM calculator
Enter the weight of a recent hard set, in lb or kg.
Enter the reps you completed with good form, from 1 to 12.
You get an estimated max plus training weights for each rep range.
Use the percentages to plan strength, size or endurance sets.
Rep max chart: reps to % of 1RM
This chart uses the same formulas as the calculator. Read across from your reps to see what percent of your max that set was, and what 1RM it predicts.
| Reps done | % of 1RM | Estimated 1RM from 100 lb | Estimated 1RM from 60 kg |
|---|---|---|---|
| 1 rep | 100% | 100 lb | 60 kg |
| 2 reps | 95% | 105 lb | 63 kg |
| 3 reps | 93% | 108 lb | 65 kg |
| 4 reps | 90% | 111 lb | 67 kg |
| 5 reps | 87% | 115 lb | 69 kg |
| 6 reps | 85% | 118 lb | 71 kg |
| 8 reps | 80% | 125 lb | 75 kg |
| 10 reps | 75% | 133 lb | 80 kg |
| 12 reps | 70% | 142 lb | 85 kg |
1RM percentage chart for training
| % of 1RM | Typical reps | Main goal |
|---|---|---|
| 90–95% | 2–4 | Maximum strength |
| 80–85% | 5–8 | Strength |
| 70–80% | 8–12 | Muscle size |
| 65–70% | 12–15 | Muscle size and endurance |
| Under 65% | 15+ | Muscular endurance, warm-ups |
The formulas explained
Your one-rep max (1RM) is the most weight you can lift once with good form. Testing it directly is tiring and carries more risk, so this calculator estimates it from a lighter set. It averages two well-known formulas:
- Epley: weight × (1 + reps ÷ 30)
- Brzycki: weight × 36 ÷ (37 − reps)
Estimates are most accurate between 3 and 10 reps. Above 10 reps, fatigue and endurance play a bigger role, so the estimate gets less reliable.
Bench press, squat and deadlift
The same formulas work for any big barbell lift. They are usually most accurate for the bench press and squat. Deadlift estimates can run a little high or low because grip and back fatigue limit high-rep sets. For machines and isolation moves like curls, use the number as a rough guide only.
How to test a true 1RM safely
- Warm up with an empty bar, then 3 to 5 lighter sets with fewer reps each time.
- Use a spotter for the bench press and safety bars for the squat.
- Take 3 to 5 minutes of rest between heavy singles.
- Stop when form breaks down. A grinding, ugly rep is not a true max.
- Beginners usually don't need a true max test. The estimate is enough to plan training.
Common 1RM mistakes
- Using a set of 15 or more reps, which gives a weak estimate.
- Counting reps with broken form.
- Training at 100% of an estimated max every week.
- Retesting too often. Every 4 to 8 weeks is plenty for most lifters.
Shop the Best Adjustable Dumbbells
You need this if: you train at home and want to hit the training weights from this calculator without buying a full rack of dumbbells.
Adjustable dumbbells let you change the weight in seconds, so you can follow the percentages for every set. We compared the best-rated models by weight range and build.
See Best Adjustable Dumbbells →Need somewhere to press? See our best weight benches.
Bench press max chart: what your reps predict
Here's what the calculator estimates if you bench 225 lb (or 100 kg) for a given number of reps. Find your own numbers with the tool above.
| Reps at 225 lb | Estimated 1RM | Same reps at 100 kg |
|---|---|---|
| 1 rep | 225 lb | 100 kg (from 100 kg) |
| 2 reps | 236 lb | 105 kg (from 100 kg) |
| 3 reps | 243 lb | 108 kg (from 100 kg) |
| 4 reps | 250 lb | 111 kg (from 100 kg) |
| 5 reps | 258 lb | 115 kg (from 100 kg) |
| 6 reps | 266 lb | 118 kg (from 100 kg) |
| 8 reps | 282 lb | 125 kg (from 100 kg) |
| 10 reps | 300 lb | 133 kg (from 100 kg) |
The same math works for squat and deadlift. For example, a 315 lb squat for 5 reps estimates about 361 lb, and a 140 kg deadlift for 3 reps estimates about 151 kg.
RPE and reps in reserve (RIR) chart
RPE (rate of perceived exertion) rates how hard a set felt on a 1 to 10 scale. It's closely tied to how many more reps you could have done, called reps in reserve.
| RPE | Reps in reserve | What it feels like |
|---|---|---|
| 10 | 0 | Maximal, no more reps possible |
| 9 | 1 | Could do one more rep |
| 8 | 2 | Could do two more |
| 7 | 3 | Fast, solid reps |
| 6 | 4 or more | Warm-up or speed work |
To use RPE with this calculator, add your reps in reserve to the reps you did. A set of 5 at RPE 8 is roughly a 7-rep max.
How to use your 1RM in a training program
Once you know your estimated max, you can program sets by percentage. A simple example for one lift, twice a week:
- Strength day: 5 sets of 5 reps at about 75 to 80% of your 1RM.
- Volume day: 3 sets of 8 to 10 reps at about 65 to 70%.
- Progress: add a small amount of weight (2.5 to 5 lb, or 1 to 2.5 kg) when all sets feel solid.
- Re-estimate every 4 to 8 weeks from a hard set, not a max attempt.
How to increase your one-rep max
- Progressive overload: gradually add weight, reps or sets over weeks.
- Train heavy, but not to failure every time: sets at 80 to 90% for low reps build max strength.
- Practice the lift often: two or three sessions a week build technique and confidence.
- Fix weak points: accessory work such as rows, triceps work for bench, and lunges for squat supports the main lift.
- Recover: sleep, enough protein and planned lighter weeks let strength actually build.
When not to test a true max
Skip a true 1RM attempt if you're new to lifting, coming back from injury, training alone without safety bars or a spotter, or if your form breaks down near your max. The estimate from a solid set of 3 to 8 reps is safer and accurate enough to plan training.
Pounds and kilograms
The calculator works in either unit. To convert, 1 kg = 2.205 lb. A 100 kg max is about 220 lb, and a 225 lb max is about 102 kg.
1RM formulas compared
There are several well-known one-rep max formulas. Our calculator averages Epley and Brzycki, two of the most widely used. Here's how five formulas compare for the same set, 225 lb for 5 reps:
| Formula | Equation | Estimate for 225 x 5 |
|---|---|---|
| Epley | weight x (1 + reps / 30) | 263 lb |
| Brzycki | weight x 36 / (37 - reps) | 253 lb |
| Lombardi | weight x reps0.10 | 264 lb |
| O'Conner | weight x (1 + 0.025 x reps) | 253 lb |
| Mayhew | 100 x weight / (52.2 + 41.9 x e-0.055 x reps) | 268 lb |
The formulas agree closely at low reps and drift apart as reps climb, which is why sets of 3 to 8 reps give the most trustworthy estimate.
How to warm up before a heavy set or 1RM test
- 5 to 10 minutes of light cardio and mobility for the joints you'll use.
- Empty bar for 10 reps.
- About 40 to 50% of your target for 5 reps.
- About 60 to 70% for 3 reps.
- About 80% for 1 or 2 reps.
- About 90% for 1 rep, then your heavy set or max attempt.
Rest 2 to 3 minutes between the heavier warm-up sets, and 3 to 5 minutes before the top attempt.
Notes for each lift
- Bench press: always use a spotter or safety arms for heavy sets. Keep your feet planted and shoulder blades squeezed together.
- Squat: set safety bars just below the bottom position. Depth should stay the same on every rep you count.
- Deadlift: grip often fails before the legs and back, so high-rep deadlift estimates can run low. Use sets of 3 to 5.
- Overhead press: small muscles tire fast, so use lower rep sets (3 to 6) for a better estimate.
- Machines and dumbbells: the formulas were built on barbell lifts, so treat machine and dumbbell estimates as a rough guide.
How to read your result
After you calculate, you'll see your estimated 1RM, the Epley and Brzycki numbers separately, and a training table. Use the table like this: pick the percentage for your goal, use the weight shown, and aim for the typical rep range listed. If the reps feel easy, your real max is probably higher. Re-calculate from that set next time.
Keep a simple log of the weight, reps and how hard each set felt. Your estimate rising over weeks is the clearest sign your training is working, with no risky max attempts needed.
Frequently asked questions
How accurate is a one-rep max calculator?
It gives a good estimate for most people, especially from sets of 3 to 10 reps. Accuracy drops for very high rep sets.
Should beginners test their one-rep max?
Most beginners don't need to. Estimating from a submaximal set is safer and good enough for planning training.
What percentage of 1RM should I train at?
Roughly 80 to 90 percent for strength, 65 to 80 percent for muscle size, and under 65 percent for muscular endurance.
Does the calculator work for squat and deadlift?
Yes. The formulas work for any big barbell lift. Deadlift estimates can be a little less exact because grip often limits high-rep sets.
Can I use RPE with this calculator?
Yes, roughly. If you stopped a set with reps left in the tank, add those reps before you enter them. For example, 5 reps at RPE 8 is about a 7-rep max.
How often should I retest my 1RM?
Every 4 to 8 weeks is enough for most lifters. Your training weights can be updated from any hard set in between.
Why is my real max different from the estimate?
Formulas assume an average lifter. People with more endurance often score higher estimates than their true max, and very strong lifters often score lower.
If I bench 225 for 5 reps, what is my max?
The calculator estimates about 258 lb by averaging the Epley and Brzycki formulas.
How many reps give the most accurate 1RM estimate?
Sets of about 3 to 8 reps usually give the most reliable estimate. Above 10 reps, accuracy drops.
Is a one-rep max calculator accurate for beginners?
It gives a reasonable starting point, but beginners improve quickly, so re-estimate every few weeks.
What is the most accurate 1RM formula?
No single formula is best for everyone. Epley and Brzycki are among the most widely used and agree closely for sets of 3 to 8 reps, which is why our calculator averages them.
Can I use this calculator in kilograms?
Yes. Choose kg next to the weight box. The estimate and training table will show in kilograms.
How much can I lift for 10 reps if my max is 200 lb?
About 75% of your max, so roughly 150 lb. The training table in the calculator shows the weight for each rep range once you enter a set.
