How to estimate your one-rep max from a normal working set with the Epley or Brzycki formula, how accurate it is, and how to use it to track strength.
You can estimate your one-rep max from any hard set of about 2 to 10 reps. The Epley formula is weight × (1 + reps ÷ 30), so 225 lb for 5 reps estimates about 263 lb. The Brzycki formula gives a similar result. Estimates are usually close for sets under 10 reps taken near failure, and get less reliable with higher reps, so use them to track trends rather than as an exact number.
Your one-rep max, the heaviest weight you can lift once with good form, is the most common way to describe strength. Testing it directly, though, is tiring, a bit risky without a good spotter or setup, and disruptive to your training for days.
The good news is that you do not need to test it to know roughly where you stand. A normal working set already contains most of the information.
An estimated 1RM (e1RM) is a prediction of your one-rep max based on a set of more than one rep. If you can squat 225 lb for 5, you can probably squat somewhere around 260 lb for 1. Formulas turn that intuition into a number.
Estimated 1RM is useful because:
Two formulas are widely used. Both work best for sets of roughly 2 to 10 reps.
e1RM = weight × (1 + reps ÷ 30)
Example: 225 lb × (1 + 5 ÷ 30) = 225 × 1.167 ≈ 263 lb.
e1RM = weight × 36 ÷ (37 − reps)
Example: 225 × 36 ÷ (37 − 5) = 225 × 36 ÷ 32 ≈ 253 lb.
The two formulas agree closely at low reps and drift apart as reps climb. Here is how they compare for a few sets:
| Set | Epley e1RM | Brzycki e1RM |
|---|---|---|
| 225 lb × 3 | 248 lb | 238 lb |
| 225 lb × 5 | 263 lb | 253 lb |
| 185 lb × 8 | 234 lb | 230 lb |
| 135 lb × 12 | 189 lb | 194 lb |
Pick one formula and stick with it. Consistency matters more than which one you choose, because what you really care about is the trend.
Reasonably accurate for most people when the set is heavy and taken close to failure. Less accurate in a few predictable situations:
Treat e1RM as a good estimate, not a guarantee. If you ever do test a true single, expect it to land within a modest range of the estimate rather than on the exact number.
The formulas assume your set was close to all-out. When it was not, you can adjust by adding your reps in reserve to the reps you did.
Example: you bench 185 lb for 6, and rate it at 2 reps in reserve. Treat it as 185 × 8 for the formula:
This is the logic behind RIR-based training. Zourdos and colleagues introduced an RIR-based effort scale in 2016 and found that experienced lifters rated proximity to failure more accurately than novices, particularly on heavier sets. Helms and colleagues described how to use those ratings to set and adjust training loads. If you are newer, your RIR ratings will be rougher, so lean on the trend over several sessions.
Strength work does not always stay in one rep range. Estimated 1RM lets you compare a heavy block with a lighter one. A worked example on squat:
| Week | Top set | Epley e1RM |
|---|---|---|
| 1 | 225 × 5 | 263 lb |
| 2 | 225 × 6 | 270 lb |
| 3 | 230 × 5 | 268 lb |
| 4 | 230 × 6 | 276 lb |
| 5 | 205 × 10 (lighter block) | 273 lb |
Week 5 looks like a step backwards on paper, since the weight dropped. The e1RM shows your strength held steady while you changed rep ranges.
Many programs prescribe loads as a percentage of your 1RM. An estimate is accurate enough to use for that. For a 263 lb e1RM, 75% is about 195 lb.
If your e1RM on a lift has not moved for three or more sessions, that is a cleaner signal of a plateau than looking at weights alone, because it accounts for rep changes.
Only if you have a reason to. Powerlifters need to know what they can lift on a platform, and some people enjoy testing. For most lifters training for muscle, strength, or general fitness, the estimate tells you what you need.
Lopez and colleagues' 2021 network meta-analysis found that heavier loads produced larger gains in maximal strength, while muscle growth was similar across loads when sets were taken close to failure. So if a heavy single is your goal, practicing heavy sets matters. If not, working sets of 4 to 10 reps and a tracked e1RM will keep you honest without the cost of max testing.
If you do test, warm up thoroughly, use safety pins or a spotter, and stop when bar speed slows sharply. If you have pain during a heavy lift, stop and see a qualified professional.
Alexandros is an iPhone app that works like a personal weightlifting coach you talk to in a chat. You log sessions in plain English, like "squat 3x5 at 225, last set hard", and it turns that into structured sets with an effort rating for each. You can ask "How has my squat progressed?" and get progress charts of top weight, estimated 1RM, and volume, with every number coming from your actual log.
That makes e1RM something you check in passing rather than calculate by hand. Its recommendations still come from double progression within your goal's rep range, and the e1RM chart is how you confirm the plan is working.
No single formula is best for everyone. Epley and Brzycki give similar answers for sets under about 10 reps. Choose one and use it consistently so your trend is comparable from week to week.
You can, but the estimate will be much less reliable. Above about 10 reps, differences in muscular endurance between people distort the result. Use a heavier set of 3 to 8 reps when you want a meaningful number.
Usually because the set you used had more reps in reserve than you thought, or because you are an endurance-leaning lifter who handles reps better than single heavy efforts. Technique and confidence with heavy singles also play a role.
Looking at it every week or two is plenty. Daily numbers bounce around with sleep, stress, and how warm you are. The trend over a month tells you far more.
