Here’s how to calculate 1 rep max from 5 reps, or any other set: enter the weight and reps and you get an estimated 1RM from the Epley and Brzycki formulas, plus a percentage table for picking training weights. No max attempt needed.
Enter a weight and the reps you completed with good form (ideally under 10 for accuracy). Your one-rep max is estimated – don’t attempt a true max without proper warm-up and a spotter.
An estimate from a rep test – accuracy is best at lower reps and drops as reps rise. Use percentages as a starting point for programming, and always train with good form and safety.
How Do You Calculate 1 Rep Max From 5 Reps?
Run the set through both formulas and average them. For 100 kg × 5 reps, Epley gives 100 × (1 + 5/30) = 116.7 kg and Brzycki gives 100 × 36 ÷ 32 = 112.5 kg, so your estimated 1RM is about 114.6 kg. That puts a set of 5 at roughly 87% of your max.
1 Rep Max Chart Percentage Table
Multiply your 1RM by each percentage to get training weights. For the 114.6 kg example:
| % of 1RM | Approx. reps | Weight |
|---|---|---|
| 95% | 2 | 108.9 kg |
| 90% | 4 | 103.1 kg |
| 85% | 6 | 97.4 kg |
| 80% | 8 | 91.7 kg |
| 75% | 10 | 85.9 kg |
| 70% | 12 | 80.2 kg |
Epley Formula vs Brzycki Formula
Formula: Epley 1RM = Weight × (1 + Reps ÷ 30). Brzycki 1RM = Weight × 36 ÷ (37 − Reps). The calculator’s estimated 1RM is the average of the two: (Epley + Brzycki) ÷ 2. When Reps = 1, the estimated 1RM is simply the weight entered. A percentage table then multiplies that 1RM by 100%, 95%, 90%, 85%, 80%, 75% and 70% to suggest training weights for roughly 1, 2, 4, 6, 8, 10 and 12 reps.
If you want to know how to calculate 1 rep max from 10 reps, this is where the two meet: at exactly 10 reps they give the same number, so 60 kg × 10 is 80 kg either way.
- Weight lifted: the load you lifted, in kg or lb (toggle the unit button)
- Reps performed: how many reps you completed with that weight using good form, ideally fewer than about 10 for best accuracy
Example Scenarios
| Weight | Reps | Estimated 1RM |
|---|---|---|
| 100 kg | 5 | 114.6 kg |
| 60 kg | 10 | 80.0 kg |
| 80 kg | 1 | 80.0 kg |
| 140 lb | 8 | 175.6 lb |
| 225 lb | 3 | 242.9 lb |
How to Calculate 1 Rep Max on Bench Press
Use a hard, short set with a full range of motion. A 225 lb bench for 5 reps estimates to about 257.8 lb. Sets of 3 to 6 reps taken close to failure make the best input; beyond about 10 reps the formulas drift apart and the estimate gets looser.
- Use a set with clean technique. Reps that needed a bounce, a shortened range of motion or a spotter’s help inflate the number.
- Enter a hard recent set, not a warm-up. Stopping with several reps left in the tank makes the estimate read low.
- Estimate each lift separately. A strong squat says little about your overhead press.
Treat the output as a planning figure for percentage-based training, not a target to chase. If you do test a true single, use safety bars or a spotter. The one-repetition maximum article on Wikipedia compares the main formulas side by side.
Common questions about estimating your 1RM
How do I calculate my 1 rep max from 5 reps?
Multiply the weight by (1 + 5 ÷ 30) for Epley and by 36 ÷ 32 for Brzycki, then average the two. For 100 kg × 5 that is 116.7 and 112.5 kg, so about 114.6 kg.How do I calculate 1 rep max on bench press?
Use a hard, clean set of 3 to 6 reps. A 225 lb bench for 5 reps gives about 257.8 lb with this calculator’s Epley and Brzycki average.Why do Epley and Brzycki give different numbers for the same lift?
They are separate formulas built on different assumptions about how strength drops as reps rise. Below 10 reps Epley reads a little higher, and at exactly 10 reps they give the same answer.How accurate is an estimated 1RM compared to actually testing it?
Rep-max formulas are estimates built from submaximal sets. They tend to be closest when you test with fewer reps (roughly under 6 to 8) and drift further from your true max as rep count rises.Is it safe to attempt a true 1-rep max in the gym?
Max-effort singles carry real injury risk, especially without a spotter, a proper warm-up or supervision. Beginners and anyone with a medical condition are better off estimating from a submaximal set, and should check with a doctor or trainer before attempting a true max.Does this work for any exercise, or just squat, bench and deadlift?
The math works for any barbell or resistance exercise, but the formulas were developed mainly from major compound lifts, so estimates for smaller isolation movements may be less precise.Related Calculators
To put your estimated max to work, the Workout Volume Calculator can total up the sets and reps in a training session, while the Push Up Calorie Calculator and Wall Sit Calorie Calculator cover the bodyweight side of a strength routine. You may also find the IPF GL Points Calculator useful. You may also find the Sinclair Calculator useful.