1RM Calculator
Estimate your one-rep max for any barbell or dumbbell lift from a normal working set — no need to grind out a true max attempt. Enter your weight and reps below for an instant estimate, plus the training percentages you need to program your next block.
| % of 1RM | Weight | Typical Reps |
|---|---|---|
| 100% | 69 kg | 1 rep (your max) |
| 95% | 65.5 kg | 2 reps |
| 90% | 62 kg | 3-4 reps |
| 85% | 58.5 kg | 5-6 reps |
| 80% | 55 kg | 7-8 reps |
| 75% | 51.5 kg | 9-10 reps |
| 70% | 48 kg | 10-12 reps |
| 65% | 44.5 kg | 12-14 reps |
| 60% | 41.5 kg | 15+ reps |
No signup required. Results update instantly as you type.
Track every lift's 1RM automatically
Log your working sets in 1RM.fit and your estimated 1RM for every lift updates itself — no manual math, ever.
What Is a 1RM, and Why Does It Matter?
Your one-rep max (1RM) is the single heaviest weight you can lift for exactly one full rep with acceptable form. It's the universal reference number strength athletes use to compare lifts across people, set training weights as a percentage of maximum, and track whether a program is actually working over months of training.
Almost every serious strength program — 5/3/1, conjugate, linear periodization, powerlifting peaking blocks — is built around percentages of your 1RM. Without a reasonably accurate 1RM for each lift, you're either guessing at your working weights or leaving progress on the table by training too light or too heavy relative to what your program intends.
The problem is that testing a true 1RM is exhausting, adds fatigue you don't need mid-training-block, and on some lifts (bench press and overhead press especially) carries genuine injury risk if you miss without a spotter. That's why almost nobody tests a true max regularly — instead, lifters estimate their 1RM from a normal working set using a rep-max formula, which is exactly what the calculator on this page does.
How This 1RM Calculator Works
Enter the weight you lifted and how many reps you got with good form (1-12 reps), and this calculator runs both numbers through two of the most widely used strength formulas, then averages the results for a more stable estimate than either formula alone.
Epley formula: 1RM = weight × (1 + reps ÷ 30). This is the formula built into most fitness apps and gym rep-max charts. It tends to estimate slightly higher, especially as your rep count climbs toward 10-12.
Brzycki formula: 1RM = weight × (36 ÷ (37 - reps)). Brzycki is generally considered the more accurate of the two in the 3-10 rep range, which is where the vast majority of real working sets fall.
Neither formula is perfect on its own — both lose accuracy above roughly 12 reps, because muscular endurance starts to matter more than raw strength the higher the rep count goes. That's why this calculator caps input at 12 reps and averages both formulas rather than leaning on just one, and why every lift-specific calculator on this site (bench, squat, deadlift, overhead press, barbell row) uses the exact same underlying math.
Why Estimating Beats Maxing Out Every Week
- It's safer. A true 1RM attempt on a lift like bench or overhead press without a dedicated spotter is one of the riskier things you can do in the gym. Estimating from a working set removes that risk entirely, on every lift.
- It's more stable. Your actual max can swing 5-10% day to day depending on sleep, stress, and how recently you've eaten. An estimate from your normal training weight is a steadier number to build a program around than a single all-out attempt.
- It's built for programming. Programs like 5/3/1 and most powerlifting templates run on percentages of your 1RM. An accurate estimate gives you correct working weights across an entire training cycle without needing a max-out session at the start of every block.
- It saves recovery. A true max effort set can cost days of central nervous system fatigue that eats into the rest of your training week. An estimate costs nothing beyond the working set you were already doing.
1RM Calculators by Lift
Want strength standards and lift-specific guidance? Use the dedicated calculator for each of the big lifts below — same formulas, plus a standards table and FAQ tailored to that lift.
1RM Calculator FAQ
How accurate is a 1RM calculator?
Within the 1-10 rep range, Epley and Brzycki are typically accurate within about 2-5% of a true tested max, though accuracy varies slightly by lift — deadlift estimates in particular tend to run a bit high due to grip and lower-back fatigue. Accuracy drops the higher your rep count goes, which is why this calculator caps input at 12 reps.
Which lifts can I use this calculator for?
Any barbell, dumbbell, or machine lift where you performed a clean, full-range working set works with this calculator's math. For the most relevant strength standards and lift-specific guidance, use the dedicated bench press, squat, deadlift, overhead press, and barbell row calculators linked below.
Should I test my true max instead of estimating?
Only occasionally — for example before a powerlifting meet, or if your estimated 1RM has stalled for 12+ weeks despite consistent training. For everyday programming, an estimate from your working sets is safer, less fatiguing, and just as useful for setting training percentages.
Why do Epley and Brzycki give different numbers?
They're built from different underlying data sets and weight the relationship between reps and fatigue slightly differently. Neither is definitively 'correct' — averaging both, as this calculator does, gives a more balanced estimate than trusting either formula alone.
Stop Estimating by Hand
1RM.fit calculates your bench, squat, deadlift, OHP, and row 1RM automatically from every set you log. Free to start.