One Rep Max Calculator
lbs
5
Formula
Estimated 1RM233 lbs
Percentage Table
| Reps | Weight (lbs) | % of 1RM |
|---|---|---|
| 1 | 233 | 100% |
| 2 | 222 | 95% |
| 3 | 210 | 90% |
| 4 | 198 | 85% |
| 5 | 187 | 80% |
| 6 | 175 | 75% |
| 7 | 163 | 70% |
| 8 | 152 | 65% |
| 9 | 140 | 60% |
| 10 | 128 | 55% |
Your one-rep max (1RM) is the heaviest weight you could lift for a single repetition of an exercise, and it underpins almost every percentage-based strength program. Instead of risking a true max attempt, this calculator estimates your 1RM from a submaximal set — the weight you lifted and the number of clean reps — using either the Epley or the Brzycki equation. It then builds a percentage table so you can read off training loads for everything from heavy triples to high-rep work.
Formula
1RM (Epley) = weight × (1 + reps/30); 1RM (Brzycki) = weight × 36/(37 − reps)
- weight
- The load lifted for the set
- reps
- Number of repetitions completed with good form
- 1RM
- Estimated one-repetition maximum
How it works
- Enter the weight you lifted and the number of reps you completed, then choose the Epley or Brzycki formula.
- Epley multiplies the weight by (1 + reps/30); Brzycki multiplies it by 36/(37 − reps). A single rep simply returns the weight as your 1RM.
- From the estimated 1RM the calculator generates a table of training loads, rounding each to the nearest pound from 100% down to 55%.
Worked example
A lifter does 225 lb for 5 reps and estimates their max with Epley.
- Apply Epley: 225 × (1 + 5/30).
- 5/30 = 0.1667, so 1 + 0.1667 = 1.1667.
- 225 × 1.1667 = 262.5 lb.
Estimated 1RM ≈ 263 lb (Brzycki gives ≈ 253 lb for the same set).
Frequently asked questions
- Should I use the Epley or Brzycki formula?
- They agree closely at low reps and diverge as reps climb — Epley tends to read a little higher. Many lifters use Epley for its simplicity; trying both gives you a sensible range for your estimated max.
- How accurate is an estimated one-rep max?
- These formulas are most reliable for sets of about 1 to 10 reps. Beyond roughly 10–12 reps, fatigue and endurance skew the estimate, so use a heavier, lower-rep set for the best accuracy.
- What are the percentage loads used for?
- Strength programs prescribe work as a percentage of 1RM — for example heavy sets at 85–95% and volume work at 65–75%. The generated table converts your estimated max into concrete weights for each percentage.
- Do I need to actually test my true one-rep max?
- Usually not. Estimating from a submaximal set avoids the injury risk and fatigue of a true max attempt while giving numbers accurate enough to program training. Only experienced lifters with a spotter should test a genuine 1RM.