1RM Calculator
Estimate your one-rep max from a set you already did. Get your 1RM, a full training-percentage table, and rep-max targets. No signup. No email.
Estimate your 1RM
Enter a set you actually did. Updates as you type.
Estimated one-rep max
263lb
Training percentages
What to load for each intensity band.
| % | Weight | Use |
|---|---|---|
| 100% | 265 lb | True 1-rep max |
| 95% | 250 lb | Heavy doubles (2 reps) |
| 90% | 235 lb | Triples (3 reps) |
| 85% | 225 lb | Strength work (4–5 reps) |
| 80% | 210 lb | Strength / size (6 reps) |
| 75% | 195 lb | Hypertrophy (8 reps) |
| 70% | 185 lb | Hypertrophy (10 reps) |
| 65% | 170 lb | Volume (12 reps) |
| 60% | 160 lb | Light volume / technique (15 reps) |
| 50% | 130 lb | Warm-up / deload |
Estimated rep maxes
The most you should expect to hit for each rep target.
| Reps | Weight |
|---|---|
| 1 rep | 255 lb |
| 2 reps | 245 lb |
| 3 reps | 240 lb |
| 5 reps | 225 lb |
| 8 reps | 205 lb |
| 10 reps | 195 lb |
| 12 reps | 190 lb |
Kovo tracks this number for every lift automatically and adjusts your weights each week so you keep progressing.
Get Kovo freeHow the 1RM estimate works
This calculator uses the Epley formula, the most widely used 1RM estimate in strength training:
1RM = weight × (1 + reps ÷ 30)
So a set of 225 for 5 reps estimates to 225 × (1 + 5 ÷ 30) ≈ 263. It's accurate within a few percent in the 3 to 8 rep range and drifts high past 10 reps, because high-rep sets test endurance as much as raw strength. This is the same formula the Kovo app uses to track your estimated 1RM on every lift, so the number here matches what you'd see in the app.
How to actually use this
Program your working sets
Most strength programs prescribe a percentage of your 1RM. The percentage table turns that into a real number on the bar. Linear strength work lives at 80 to 90%. Hypertrophy work sits at 65 to 80%. Speed and technique work stays at 50 to 60%.
Pick the right test set
Don't use a grindy max-effort double or a 20-rep burnout. The estimate is most accurate from a clean set of 3 to 6 reps where you stopped with about one rep in reserve.
Recalculate as you get stronger
Your 1RM moves. Re-estimate it every few weeks from your best recent set so your percentages stay honest. If you'd rather not do this by hand, Kovo tracks it automatically and adjusts your weights for you every week.
FAQ
What is a one-rep max?
Your one-rep max (1RM) is the most weight you can lift for a single rep of an exercise with good form. It's the standard way to measure strength and the anchor for percentage-based training programs. Most lifters never actually test a true 1RM because it's risky and hard to recover from, so they estimate it from a heavier set instead.
How accurate is a 1RM calculator?
Very accurate in the 3 to 8 rep range, usually within a few percent of a real tested max. Accuracy drops as reps climb because endurance starts to matter more than pure strength. For the best estimate, use a hard set of 3 to 6 reps where you had maybe one rep left in the tank.
Which formula does this calculator use?
It uses the Epley formula: estimated 1RM = weight × (1 + reps ÷ 30). It's the same formula the Kovo app uses internally to track your estimated 1RM on every lift, so the number you get here matches what you'd see in the app.
How do I use the training-percentage table?
Find the rep range your program calls for, then load the matching percentage. A program that says '5×5 at 80%' means do five sets of five at the 80% weight in the table. Most strength work lives between 70% and 90%; hypertrophy work sits around 65% to 80%; warm-ups and deloads use 50% to 60%.
Should I actually test my true 1RM?
Usually not. A real 1RM attempt is risky, technically demanding, and takes days to recover from. An estimate from a heavy set of 3 to 6 reps gives you almost the same information with none of the downside. Save true max attempts for a meet or a planned testing week with a spotter.
Why does my estimate keep changing as I get stronger?
That's the point. Your 1RM isn't fixed — it moves every time your strength changes. Recalculate it every few weeks from your best recent set so your training percentages stay accurate. The Kovo app does this for you automatically on every lift and adjusts your weights each week.
Stop doing this math by hand
Kovo tracks your estimated 1RM on every lift, adjusts your weights each week, and builds your whole program so you never plan a workout again. Plus streaks, quests, levels, and friends in your gym. Free on iOS and Android.