Can I use this for assistance exercises (curls, lateral raises)?

Mathematically yes, but you'll get the cleanest results on compound lifts — squat, bench, deadlift, overhead press, row. The formulas were built around those movements. On isolation work at high reps (think curls for 15+), the predictions start to overestimate because muscular endurance becomes the limiter rather than pure strength. For accessory lifts, just program by reps and feel; don't bother chasing a 1RM number on lateral raises.

How often should I retest?

For intermediate lifters, every 6 to 8 weeks — long enough for an adaptation block to take hold but not so long that your number goes stale. Beginners can retest every 3 to 4 weeks because progress is rapid. Advanced lifters every 10 to 12 weeks since gains slow significantly. One non-negotiable: always use the same formula version when comparing, so a Brzycki number isn't being compared against an Epley number. Otherwise you're measuring the formula change, not your strength change.

What about programs that prescribe %1RM?

Programs like 5/3/1, Smolov, and Sheiko all build around percentages of your max — that's where this calculator's output plugs in. Important nuance: most quality programs apply percentages to a 'training max' of 90 percent of your true 1RM, not the max itself. That 10 percent buffer absorbs bad sleep, light deloads, and the inevitable bar speed decay across a hard work set. Skip the buffer and you'll grind to a halt in 8 weeks. Use the training max, not the true max, for week-to-week programming.

Does the formula work for women?

Yes — the prediction math is identical across genders. The regressions were derived from population studies that included both. Women's 1RMs typically land at 50 to 70 percent of men's at the same body weight (the gap is bigger on upper-body lifts, closer on lower body), but the rep-to-percentage relationship doesn't change. Whether you're a woman lifting in a gym in Lahore or Dubai or anywhere else, the formula treats your inputs the same way.

How do I safely test my real 1RM?

Warm up thoroughly — 10 to 15 minutes of light cardio plus dynamic mobility work — then ladder up: 50 percent for 5 reps, 70 percent for 3, 85 percent for 1, 92 percent for 1, then attempt your max. Always use a spotter or safety bars set just below your bottom range. Stop the lift if form breaks down — a missed rep on a quality day is fine; a torn pec or a back injury from grinding through bad form can cost you 6 to 12 months of training. Never max out alone, never max out on a bad sleep night.

Premium Converters

One-Rep Max (1RM) Calculator

Health

Estimate your true one-rep max from any sub-maximal set using six published formulas (Epley, Brzycki, Lombardi, Lander, O'Conner, Wathen).

Health

One-Rep Max (1RM) Calculator

Generated on May 23, 2026

Estimate your one-rep max (1RM) — the heaviest weight you can lift once with proper form — from a sub-maximal set. Useful for building training plans without actually attempting a true 1RM (which is risky and exhausting).

Weight lifted

Reps performed (2–15)

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Premium Converters

One-Rep Max Estimate

Estimated 1RM 114.9 kg (avg of 6 formulas)

Generated

5/23/2026

Estimated 1RM (average of 6 formulas)

114.9 kg

Epley

116.7 kg

Brzycki

112.5 kg

Lombardi

117.5 kg

Lander

113.7 kg

O'Conner

112.5 kg

Wathen

116.6 kg

Predicted Working Weights

Based on your estimated 1RM of 114.9 kg.

Reps	% of 1RM	Weight	Use case
1	100%	114.9 kg	Strength / power
2	95%	109.2 kg	Strength / power
3	93%	106.9 kg	Strength / power
4	90%	103.4 kg	Strength
5	87%	100 kg	Strength
6	85%	97.7 kg	Strength
8	80%	91.9 kg	Hypertrophy
10	75%	86.2 kg	Hypertrophy
12	70%	80.4 kg	Endurance / muscular endurance
15	65%	74.7 kg	Endurance / muscular endurance

Step-by-step calculation

Formula

Epley: 1RM = w × (1 + r/30). Brzycki: 1RM = w × 36/(37 − r). Lombardi: 1RM = w × r^0.10.

1You lifted 100 kg for 5 reps.
2Epley = 100 × (1 + 5/30) = 116.67 kg
3Brzycki = 100 × 36 / (37 − 5) = 112.5 kg
4Lombardi = 100 × 5^0.10 = 117.46 kg
5Average of 6 published formulas = 114.9 kg
6Working-weight table is computed as % × 1RM, where % comes from standard rep-intensity tables.

Quick Answer

Estimate your true one-rep max from any sub-maximal set using six published formulas (Epley, Brzycki, Lombardi, Lander, O'Conner, Wathen).

Overview — One-Rep Max (1RM) Calculator

Health

The One-Rep Max (1RM) Calculator estimates the heaviest weight you can lift once with proper form, based on a sub-maximal set you've actually performed. Attempting a true 1RM is risky (high injury potential), exhausting, and requires a spotter, so most lifters use prediction formulas instead. This calculator averages six widely-cited formulas — Epley (1985), Brzycki (1993), Lombardi (1989), Lander (1985), O'Conner (1989), and Wathen (1994) — to give a robust estimate, then projects your training weights for any rep range from 1RM down to 15RM.

Formula

Epley: 1RM = w × (1 + r/30).   Brzycki: 1RM = w × 36 / (37 − r).   Lombardi: 1RM = w × r^0.10.   (w = weight lifted, r = reps performed).

The current raw bench-press world record is 355 kg (Julius Maddox) — heavier than two adult tigers.

An untrained adult male typically benches 0.5-0.8× body weight; intermediate trainees 1.2-1.5×; advanced 1.8-2.0×; elite 2.5×+.

Squat ratios run higher: untrained ~0.75×; intermediate ~1.5×; advanced ~2.25×; elite 3×+.

By Muhammad Salman SaleemUpdated: May 23, 2026MethodologyFree, no sign-upRuns in your browser — your data stays private

From the editors — what to know before you start

You just finished a hard set of 5 at 100 kg on the bench and you want to know — realistically, no ego — what your true one-rep max would be. Maxing out for real is rough. It's exhausting, it requires a spotter, the form risk is genuinely high, and if you miss, you can hurt yourself badly. So lifters use prediction formulas instead, and there are six well-cited ones (Epley, Brzycki, Lombardi, Lander, O'Conner, Wathen) that all sit within roughly 5 to 10 percent of each other for moderate rep ranges. This calculator averages all six so you don't have to pick favourites. Use the number to plan your training percentages — 5 by 5 work sits around 85 percent, hypertrophy at 70 to 80, max strength at 90-plus — and remember that 'training max' (90 percent of true max) is what most programs actually prescribe against, with the 10 percent buffer absorbing fatigue and form decay. Honest take: most lifters chase their numbers obsessively for two years and then realise the gains came from consistency, sleep, and protein, not from a perfect calculator readout. The 1RM is a tool to plan training, not a measure of your worth as a human.

Pro tips most people learn the hard way

All six formulas drift apart above 10 reps because endurance starts dominating over strength. If you did 15 reps, your estimated 1RM is a rough sketch — for an honest number, retest with a set of 3 to 8 reps where the regressions are most accurate.
Brzycki tends to be conservative; Epley slightly more generous on compound lifts. The average across all six is your safest planning number — that's what the headline output gives you. Don't cherry-pick the highest formula because it makes you feel strong.
Most strength programs prescribe percentages against a 'training max' of 90 percent of your true 1RM, not the max itself. This 10 percent buffer absorbs bad sleep, light deloads, and the inevitable bar speed decay across a hard work set. Skip the buffer and you'll grind to a halt in 8 weeks.
Retest every 6 to 8 weeks for intermediate lifters, every 3 to 4 weeks for beginners, every 10 to 12 weeks for advanced. Always use the same formula version to keep comparison apples to apples — a Brzycki number isn't directly comparable to an Epley number.
Never max out alone, never max out on a bad sleep night, never max out without proper warm-up ladders. A torn pec or a back injury from a missed lift can cost you 6 to 12 months of training — far more than the ego hit of going slightly conservative on a heavy day.

?What is the One-Rep Max (1RM) Calculator?

The Formula

Epley: 1RM = w × (1 + r/30). Brzycki: 1RM = w × 36 / (37 − r). Lombardi: 1RM = w × r^0.10. (w = weight lifted, r = reps performed).

All six formulas are statistical regressions fit to thousands of real-world lifters. They agree closely for moderate reps (3-8) but diverge at higher rep counts (12+) where individual variability dominates. Brzycki is the most commonly cited; Epley is slightly more accurate for compound movements (squat, deadlift, bench); Lombardi tends to underestimate at low reps. For a balanced estimate use the average — that's what this calculator's headline number gives. None of these formulas work for repetitions beyond 15 (the relationship between reps and intensity becomes too non-linear).

% of 1RM by Reps — Working Weight Reference

Standard relationship between reps and intensity (% of 1RM). Use to plan training sets.

Reps	% of 1RM	Training adaptation	Example use
1	100%	Maximum strength	Powerlifting meet, true max
2	95%	Maximum strength	Heavy doubles
3	93%	Strength	Powerlifting / heavy training
5	87%	Strength	5×5 programs (StrongLifts, Starting Strength)
6	85%	Strength	5/3/1 main work
8	80%	Strength + hypertrophy	Hypertrophy training
10	75%	Hypertrophy	Bodybuilding standard
12	70%	Hypertrophy + endurance	Higher-rep bodybuilding
15	65%	Muscular endurance	Endurance / metabolic conditioning

Put It in Perspective

The current raw bench-press world record is 355 kg (Julius Maddox) — heavier than two adult tigers.

An untrained adult male typically benches 0.5-0.8× body weight; intermediate trainees 1.2-1.5×; advanced 1.8-2.0×; elite 2.5×+.

Squat ratios run higher: untrained ~0.75×; intermediate ~1.5×; advanced ~2.25×; elite 3×+.

Practical Examples

Bench-pressed 100 kg for 5 reps → estimated 1RM ~115 kg.

Squatted 140 kg for 3 reps → estimated 1RM ~150 kg.

Deadlifted 180 kg for 8 reps → estimated 1RM ~225 kg (use Brzycki for the most reliable estimate at 8+ reps).

Power-hypertrophy training: work at 70-85% of 1RM (5-12 reps). Maximum strength: 85-95% (1-5 reps). Endurance: 60-70% (12-20 reps).

Powerlifting meet warm-up: bar → 40% → 60% → 75% → 85% → 92% → 96% → 100% (your opener) → 102-105% (your second/third attempts).

Frequently Asked Questions

All six sit within 5 to 10 percent of each other for moderate-rep sets (3 to 10 reps), which is where the regressions are most reliable. Brzycki is the most commonly cited and tends to be a touch conservative — it'll usually underestimate slightly, which is honestly the safer error to make. Epley runs a little more generous on compound lifts. The headline number on this calculator averages all six so you don't have to pick favourites and don't get tempted to cherry-pick whichever formula makes you feel strongest.

Popular Conversions

Jump to a ready-made conversion — useful for quick reference and sharing:

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Estimate Basal Metabolic Rate using the Mifflin-St Jeor equation by sex, age, weight and height — the resting kcal/day baseline for diet planning.

TDEE Calculator

Compute Total Daily Energy Expenditure from BMR and activity multiplier (sedentary to extra active) to set kcal targets for cutting, maintenance, or bulking.

Ideal Weight Calculator

Find your ideal weight range in kg and lb using the Robinson, Miller, Devine and Hamwi formulas alongside the BMI 18.5-24.9 healthy band for men and women.

Water Intake Calculator

Calculate daily water intake in millilitres or litres from body weight and exercise minutes, with hot-climate, pregnancy and breastfeeding adjustments.

Body Fat Calculator

Estimate body fat percentage with the US Navy tape-measure method using neck, waist and hip in cm or inches — a no-cost alternative to DEXA scans for men and women.

Macro Calculator

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Premium Converters

One-Rep Max (1RM) Calculator

Health

Estimate your true one-rep max from any sub-maximal set using six published formulas (Epley, Brzycki, Lombardi, Lander, O'Conner, Wathen).

Health

One-Rep Max (1RM) Calculator

Generated on May 23, 2026

Weight lifted

Reps performed (2–15)

Save / share— download or share to WhatsApp, Facebook & more

Premium Converters

One-Rep Max Estimate

Estimated 1RM 114.9 kg (avg of 6 formulas)

Generated

5/23/2026

Estimated 1RM (average of 6 formulas)

114.9 kg

Epley

116.7 kg

Brzycki

112.5 kg

Lombardi

117.5 kg

Lander

113.7 kg

O'Conner

112.5 kg

Wathen

116.6 kg

Predicted Working Weights

Based on your estimated 1RM of 114.9 kg.

Reps	% of 1RM	Weight	Use case
1	100%	114.9 kg	Strength / power
2	95%	109.2 kg	Strength / power
3	93%	106.9 kg	Strength / power
4	90%	103.4 kg	Strength
5	87%	100 kg	Strength
6	85%	97.7 kg	Strength
8	80%	91.9 kg	Hypertrophy
10	75%	86.2 kg	Hypertrophy
12	70%	80.4 kg	Endurance / muscular endurance
15	65%	74.7 kg	Endurance / muscular endurance

Step-by-step calculation

Formula

Epley: 1RM = w × (1 + r/30). Brzycki: 1RM = w × 36/(37 − r). Lombardi: 1RM = w × r^0.10.

1You lifted 100 kg for 5 reps.
2Epley = 100 × (1 + 5/30) = 116.67 kg
3Brzycki = 100 × 36 / (37 − 5) = 112.5 kg
4Lombardi = 100 × 5^0.10 = 117.46 kg
5Average of 6 published formulas = 114.9 kg
6Working-weight table is computed as % × 1RM, where % comes from standard rep-intensity tables.

Quick Answer

Estimate your true one-rep max from any sub-maximal set using six published formulas (Epley, Brzycki, Lombardi, Lander, O'Conner, Wathen).

Overview — One-Rep Max (1RM) Calculator

Health

Formula

Epley: 1RM = w × (1 + r/30).   Brzycki: 1RM = w × 36 / (37 − r).   Lombardi: 1RM = w × r^0.10.   (w = weight lifted, r = reps performed).

The current raw bench-press world record is 355 kg (Julius Maddox) — heavier than two adult tigers.

An untrained adult male typically benches 0.5-0.8× body weight; intermediate trainees 1.2-1.5×; advanced 1.8-2.0×; elite 2.5×+.

Squat ratios run higher: untrained ~0.75×; intermediate ~1.5×; advanced ~2.25×; elite 3×+.

By Muhammad Salman SaleemUpdated: May 23, 2026MethodologyFree, no sign-upRuns in your browser — your data stays private

From the editors — what to know before you start

Pro tips most people learn the hard way

All six formulas drift apart above 10 reps because endurance starts dominating over strength. If you did 15 reps, your estimated 1RM is a rough sketch — for an honest number, retest with a set of 3 to 8 reps where the regressions are most accurate.
Brzycki tends to be conservative; Epley slightly more generous on compound lifts. The average across all six is your safest planning number — that's what the headline output gives you. Don't cherry-pick the highest formula because it makes you feel strong.
Most strength programs prescribe percentages against a 'training max' of 90 percent of your true 1RM, not the max itself. This 10 percent buffer absorbs bad sleep, light deloads, and the inevitable bar speed decay across a hard work set. Skip the buffer and you'll grind to a halt in 8 weeks.
Retest every 6 to 8 weeks for intermediate lifters, every 3 to 4 weeks for beginners, every 10 to 12 weeks for advanced. Always use the same formula version to keep comparison apples to apples — a Brzycki number isn't directly comparable to an Epley number.
Never max out alone, never max out on a bad sleep night, never max out without proper warm-up ladders. A torn pec or a back injury from a missed lift can cost you 6 to 12 months of training — far more than the ego hit of going slightly conservative on a heavy day.

?What is the One-Rep Max (1RM) Calculator?

The Formula

Epley: 1RM = w × (1 + r/30). Brzycki: 1RM = w × 36 / (37 − r). Lombardi: 1RM = w × r^0.10. (w = weight lifted, r = reps performed).

% of 1RM by Reps — Working Weight Reference

Standard relationship between reps and intensity (% of 1RM). Use to plan training sets.

Reps	% of 1RM	Training adaptation	Example use
1	100%	Maximum strength	Powerlifting meet, true max
2	95%	Maximum strength	Heavy doubles
3	93%	Strength	Powerlifting / heavy training
5	87%	Strength	5×5 programs (StrongLifts, Starting Strength)
6	85%	Strength	5/3/1 main work
8	80%	Strength + hypertrophy	Hypertrophy training
10	75%	Hypertrophy	Bodybuilding standard
12	70%	Hypertrophy + endurance	Higher-rep bodybuilding
15	65%	Muscular endurance	Endurance / metabolic conditioning

Put It in Perspective

The current raw bench-press world record is 355 kg (Julius Maddox) — heavier than two adult tigers.

An untrained adult male typically benches 0.5-0.8× body weight; intermediate trainees 1.2-1.5×; advanced 1.8-2.0×; elite 2.5×+.

Squat ratios run higher: untrained ~0.75×; intermediate ~1.5×; advanced ~2.25×; elite 3×+.

Practical Examples

Bench-pressed 100 kg for 5 reps → estimated 1RM ~115 kg.

Squatted 140 kg for 3 reps → estimated 1RM ~150 kg.

Deadlifted 180 kg for 8 reps → estimated 1RM ~225 kg (use Brzycki for the most reliable estimate at 8+ reps).

Power-hypertrophy training: work at 70-85% of 1RM (5-12 reps). Maximum strength: 85-95% (1-5 reps). Endurance: 60-70% (12-20 reps).

Powerlifting meet warm-up: bar → 40% → 60% → 75% → 85% → 92% → 96% → 100% (your opener) → 102-105% (your second/third attempts).

Frequently Asked Questions

Popular Conversions

Jump to a ready-made conversion — useful for quick reference and sharing:

Browse all Health

BMI Calculator

Calculate Body Mass Index against WHO and Asian-population thresholds for men and women using kg or lb, cm or inches, with healthy-range guidance.

BMR Calculator

Estimate Basal Metabolic Rate using the Mifflin-St Jeor equation by sex, age, weight and height — the resting kcal/day baseline for diet planning.

TDEE Calculator

Compute Total Daily Energy Expenditure from BMR and activity multiplier (sedentary to extra active) to set kcal targets for cutting, maintenance, or bulking.

Ideal Weight Calculator

Find your ideal weight range in kg and lb using the Robinson, Miller, Devine and Hamwi formulas alongside the BMI 18.5-24.9 healthy band for men and women.

Water Intake Calculator

Calculate daily water intake in millilitres or litres from body weight and exercise minutes, with hot-climate, pregnancy and breastfeeding adjustments.

Body Fat Calculator

Estimate body fat percentage with the US Navy tape-measure method using neck, waist and hip in cm or inches — a no-cost alternative to DEXA scans for men and women.

Macro Calculator

Calculate your daily protein, carbohydrate, and fat targets based on your goals.

Pregnancy Due Date Calculator

Estimate baby's due date using Naegele's rule (LMP + 280 days), adjusted for cycle length, with conception date, trimester boundaries and current week and day.

Browse all Health calculators & converters

See every tool in this category, plus FAQs and category-specific guides.

Browse other categories

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One-Rep Max (1RM) Calculator — your true one-rep max from any sub-maximal set using… | Premium Converters

Premium Converters

Premium Converters

One-Rep Max (1RM) Calculator

One-Rep Max (1RM) Calculator

One-Rep Max Estimate

Predicted Working Weights

Step-by-step calculation

Overview — One-Rep Max (1RM) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the One-Rep Max (1RM) Calculator?

The Formula

% of 1RM by Reps — Working Weight Reference

Put It in Perspective

Practical Examples

Frequently Asked Questions

Popular Conversions

Embed this calculator on your site

Browse other categories

Premium Converters

One-Rep Max (1RM) Calculator

One-Rep Max (1RM) Calculator

One-Rep Max Estimate

Predicted Working Weights

Step-by-step calculation

Overview — One-Rep Max (1RM) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the One-Rep Max (1RM) Calculator?

The Formula

% of 1RM by Reps — Working Weight Reference

Put It in Perspective

Practical Examples

Frequently Asked Questions

Popular Conversions

Embed this calculator on your site

Browse other categories

Premium Converters

Premium Converters

One-Rep Max (1RM) Calculator

One-Rep Max (1RM) Calculator

Predicted Working Weights

Step-by-step calculation

Overview — One-Rep Max (1RM) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the One-Rep Max (1RM) Calculator?

The Formula

% of 1RM by Reps — Working Weight Reference

Put It in Perspective

Practical Examples

Frequently Asked Questions

Which formula is most accurate?

Can I use this for assistance exercises (curls, lateral raises)?

How often should I retest?

What about programs that prescribe %1RM?

Does the formula work for women?

How do I safely test my real 1RM?

Popular Conversions

Embed this calculator on your site

More Health Tools

Browse other categories

Premium Converters

One-Rep Max (1RM) Calculator

One-Rep Max (1RM) Calculator

Predicted Working Weights

Step-by-step calculation

Overview — One-Rep Max (1RM) Calculator

From the editors — what to know before you start

Pro tips most people learn the hard way

?What is the One-Rep Max (1RM) Calculator?

The Formula

% of 1RM by Reps — Working Weight Reference

Put It in Perspective

Practical Examples

Frequently Asked Questions

Which formula is most accurate?

Can I use this for assistance exercises (curls, lateral raises)?

How often should I retest?

What about programs that prescribe %1RM?

Does the formula work for women?

How do I safely test my real 1RM?

Popular Conversions

Embed this calculator on your site

More Health Tools

Browse other categories