Free tool
1RM Calculator
Estimate your one-rep max from any rep set — plus a full training load table from 67% to 100% for programming by percentage. Uses Epley, Brzycki, Lombardi, and O'Conner formulas.
Calculator
Your estimated 1RM
Used for the results label only. Epley and Brzycki aren't exercise-specific.
Best accuracy between 2 and 10 reps. 1 rep = your actual 1RM.
Estimated 1RM (Bench press)
258 lb
Training load table
| % | Weight (lb) | Typical reps |
|---|---|---|
| 100% | 260 | 1 rep |
| 95% | 245 | 2 reps |
| 93% | 240 | 3 reps |
| 90% | 230 | 4 reps |
| 87% | 225 | 5 repsyour set |
| 85% | 220 | 6 reps |
| 83% | 215 | 7 reps |
| 80% | 205 | 8 reps |
| 77% | 200 | 9 reps |
| 75% | 195 | 10 reps |
| 70% | 180 | 12 reps |
| 67% | 175 | 15 reps |
Weights rounded to the nearest 5 lb. Use as a starting point and adjust for exercise and fatigue on the day.
Under the hood
How this calculator works
Every 1RM formula models the same relationship: as weight goes up, the number of reps you can do with it goes down — and the curve is predictable. Plug in any heavy set and the math extrapolates to what you'd lift for a single rep.
The four formulas
- Epley (1985):
1RM = weight × (1 + reps / 30) - Brzycki (1993):
1RM = weight × 36 / (37 − reps) - Lombardi (1989):
1RM = weight × reps^0.10 - O'Conner (1989):
1RM = weight × (1 + 0.025 × reps)
Epley and Brzycki are the two most referenced in strength research — they agree closely in the 2–10 rep range, which is where 1RM estimation is most reliable. We show all four so you can see the spread; the big headline number is the Epley/Brzycki average.
The training load table
Once you have an estimated 1RM, you can program by percentage. Standard ranges: 70–80% of 1RM for hypertrophy (8–12 reps), 80–90% for strength (3–6 reps), 90%+ for peak strength and top singles. Weights are rounded to the nearest 5 lb/kg since that's the smallest plate change on most bars.
Getting the most accurate estimate
The sweet spot is a heavy set of 3–5 reps taken close to but not atfailure — typically RPE 8–9. That's enough rep data for the formula to extrapolate cleanly, without the metabolic fatigue that distorts high-rep sets.
Avoid plugging in AMRAP (as-many-reps-as-possible) sets from the end of a workout — accumulated fatigue means your actual fresh 1RM is higher than the calculator will suggest. Use your first working set of the day, or a stand-alone heavy set done fresh.
Use your numbers
Got your 1RM? Program around it with these:
- Progressive overload guide → how to add weight intelligently
- Compound vs isolation exercises → what to prioritize for strength
- Macro calculator → fuel your training
Frequently asked
Questions people ask about this
How accurate is a 1RM calculator?
Accuracy is best in the 2–6 rep range — within about 5% of a true tested max for most trained lifters. It drops as reps climb, because the closer you get to true failure the more the weight curve bends: a 15-rep set isn't linearly related to a 1RM. For anything above 10 reps, treat the number as a ballpark, not a target.
Which formula is most accurate — Epley or Brzycki?
They're similar and both well-validated. Brzycki tends to produce slightly lower estimates; Epley slightly higher. For most lifters the difference is under 3%. This calculator shows both plus Lombardi and O'Conner so you can see the spread, and the big headline number is the Epley/Brzycki average — the standard choice in strength-training research.
Should I actually test my 1RM?
Only if you need the number for a powerlifting meet, a specific program, or pure curiosity — and only if your technique is solid. Testing a true 1RM is high-risk (peak fatigue, form breakdown, injury potential) and detrains for ~5–10 days afterwards. For most training purposes, an estimate from a heavy 3–5 rep set is safer and nearly as useful.
What's a good rep set to plug in for accuracy?
A heavy set of 3–5 reps taken close to (but not at) failure gives the best 1RM estimate. Sets in the 1–2 range give accurate numbers but are basically testing. Sets above 8 reps introduce too much metabolic fatigue for the formulas to hold cleanly.
How should I use the training load table?
It's a starting map for programming. 70–80% of 1RM is the standard hypertrophy range (8–12 reps). 80–90% is strength (3–6 reps). 90%+ is peak strength and top singles. Adjust the exact load based on how the bar moves on the day — RPE beats percentages when fatigue is real.
Does this work for deadlift, squat, and bench equally?
The formulas don't care about the lift, but rep performance does vary by exercise. Most lifters can grind out more reps at a given percentage on squat and deadlift than on bench, because those lifts have more room for leverage and grind. Treat the estimate as a baseline and expect deadlift numbers to run a little higher than the formula predicts for high-rep sets.
I'm a beginner — should I even be calculating a 1RM?
You can estimate for fun, but don't program around it. Beginner strength goes up too fast — the number from a 5×5 set this week is already wrong in two weeks. Run a progressive overload program (add weight every session while form holds) for 3–6 months before percentage-based training becomes worth the math.
Why are there slightly different numbers between calculators online?
Different sites use different formula blends, default to different ones, or round differently. The underlying math is the same across Epley, Brzycki, Lombardi, and O'Conner — only the coefficients and curve shape differ. Any two reputable calculators should agree within 3–5% on a 2–8 rep input.
Estimates are starting points, not guaranteed numbers. Real-world 1RM varies with sleep, hydration, exercise-specific skill, and fatigue. Never attempt a true 1RM test without a spotter and proper warm-up ramp. If you're new to lifting, work with a qualified coach or run a linear progression program before programming by percentage.