One Rep Max Calculator

Within 5% of your true 1RM when the input set is between 1 and 6 reps. Accuracy degrades as reps increase. At 10 reps expect ±7 to 10%; beyond 10 reps formulas become unreliable.

For training-percentage planning, that's accurate enough. Your 1RM also fluctuates day to day by 5% or more based on sleep, nutrition, stress, and recovery.

No single formula is universally most accurate. Epley and O'Conner perform well across 3 to 8 reps; Brzycki tends conservative; Mayhew tends higher. Lombardi handles higher rep ranges better.

Averaging multiple formulas (which this calculator does) smooths out bias and gives the most robust single estimate.

Pick a weight you can lift with good form for somewhere between 3 and 10 reps. Lift it to technical failure (the rep before form breaks down). Enter weight and rep count into the calculator.

For best accuracy, use a weight that puts you in the 3 to 6 rep range. This minimizes formula error.

1RM = Weight × (1 + Reps/30). Most widely used 1RM estimation formula, default in most fitness apps. For 225 lb × 5 reps, Epley estimates 262.5 lb.

Developed empirically by Boyd Epley in 1985. Most accurate between 1 and 10 reps.

1RM = Weight × 36/(37 − Reps). Linear model developed by Matt Brzycki in 1993 that tends to give conservative estimates as reps increase. Popular for safety-conscious programming.

For 225 lb × 5 reps, Brzycki estimates 253 lb. Becomes mathematically undefined at 37 reps and unreliable above 12.

80% is typically prescribed for 6 to 8 rep strength-and-size training. Multiply 1RM by 0.80.

250 lb 1RM = 200 lb. 300 lb 1RM = 240 lb. 350 lb 1RM = 280 lb. Use the Percentage Chart above to look up any percentage from 50 to 100% for any 1RM value.

90% is for max-strength training, typically 3 to 4 reps per set. Multiply 1RM by 0.90.

200 lb 1RM = 180 lb. 300 lb 1RM = 270 lb. 400 lb 1RM = 360 lb. At 90%+ most programs cap weekly volume to avoid CNS burnout.

No. Strength is exercise-specific. Your bench press 1RM doesn't predict squat 1RM, and even back squat 1RM doesn't predict front squat 1RM accurately. Each lift recruits muscles in different proportions and uses different leverage.

Always estimate 1RM separately for each lift you want to program with percentages.

Most coaches recommend that beginners (under one year of consistent training) avoid direct 1RM testing. Form is still developing, injury risk is elevated, and the CNS isn't trained for maximal effort.

Use estimation calculators with 5 to 8 rep submaximal sets instead. Beginners' 1RM also rises so quickly that tested numbers are outdated within weeks.

Every 8 to 12 weeks is sufficient for most lifters, typically at the end of a training block before starting a new program. Testing more drains the CNS and raises injury risk.

Beginners can re-estimate every 4 to 6 weeks because rapid early gains make older numbers stale faster.

It depends on bodyweight and training history. For a 180 lb male, 225 lb bench is novice-to-intermediate threshold (1.25× BW). For a 140 lb male, solidly intermediate (1.6× BW). For a 220 lb male, closer to beginner-to-novice.

The "1 plate, 2 plates, 3 plates" (135, 225, 315) progression is a useful informal milestone but tells you more about psychology than strength. Bodyweight-relative benchmarks are more accurate.

1RM is your true maximum, what you could lift on your best day. A "training max" is typically 90% of your estimated 1RM, used by programs like 5/3/1 to set sustainable working percentages.

If your estimated 1RM is 300 lb, your training max would be 270 lb, and percentages would be calculated off 270 lb. Safer and more sustainable for long-term programming.