One-Rep Max (1RM) Calculator: Estimate Your True Strength

Updated Jul 2026

Your result

Estimated one-rep max

Enter your values, then calculate to see a verified result.

Inputs usedReview the information used for this result.

Full calculation and sourcesReview all seven equations, the selected method, input range, training percentage, and load-rounding convention.

Versioned calculationFormula v3.4.0

What is calculated

Seven labeled equations estimate 1RM from the same technically consistent rep set.

What remains visible

All seven formulas, exact and loadable percentages, and formula-consistent repetition targets stay separate.

Important boundary

An estimated 1RM is a programming aid, not a required maximal attempt.

Enter a rep setUse a technically consistent set within 1 to 15 repsTreat 11-15 reps as a higher-uncertainty estimate

Apply the selected equationKeep the method visibleEpley or Brzycki

Treat it as an estimateDo not make the estimate a required attemptUse normal lifting safety

Interpretation

The calculated result is .

The formula, normalized inputs, and rounding remain visible for review.

Use the formula range and safety boundary before turning the estimate into a training decision.

Use this result

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Keep exploring

4 related pages

Method and test recordFormula v3.4.0

Recorded scope: Epley, Brzycki and other equations model the rep-load relationship differently. Show the selected estimate and, if multiple equations are available, a range or formula comparison. Do not average formulas without explaining why.
Publisher: CalculatorGeek
Recorded review date: 2026-09-21
Next source review: 2027-09-21 or when a cited formula, federation rule, or program source changes
Definition fixtures: 3 configured scenarios
Published examples: 2 shown below

Recorded method

Source-package vectors, independent formula checks, JavaScript/PHP differential parity, invalid-input boundaries, unit-equivalence cases, result-layout checks, contextual-link audit, schema validation, and responsive browser QA.

These records describe the published model and reference tests. A test-case count is not a certification of every possible input or an independent specialist review. Editorial policy

Known limitations

Publish after every selectable equation, rep limit, rounding rule and percentage table is verified; retain a prominent lifting-safety boundary.

Method sources

Latest model update

2026-09-21 - Verified the 70 kg by 15 Epley benchmark, added lift labeling, exposed all formula estimates, and separated exact, loadable, and formula-consistent repetition tables.

Reference inputs and expected results

These published examples are separate from the configured definition fixtures and any additional automated assertions. Expected values use the stated output units; invalid inputs are intended to be rejected.

Case	Inputs	Expected result
Seven-formula five-rep mean		epley=116.6666667, brzycki=112.5, lombardi=117.4618943, target_load=92.5, classification=high_confidence
One rep identity		one_rm=102.05828325, low_estimate=102.05828325

Report an issue with this tool. Include the page URL, units, expected answer, and steps to reproduce. Do not include sensitive personal information.

On this page

Use a hard, technically consistent set

Enter the load and completed repetitions from one exercise. Results are usually more useful from a challenging set of roughly 2-10 clean reps than from a high-repetition endurance set. Use the same exercise, range of motion and equipment when comparing dates.

Continue with the 1RM Percentage Chart. Turn a max into exact and loadable percentage targets.

For the next decision, read 1RM versus training max.

Compare formulas instead of hiding disagreement

Epley, Brzycki and other equations model the rep-load relationship differently. Show the selected estimate and, if multiple equations are available, a range or formula comparison. Do not average formulas without explaining why.

Continue with the Training Max Calculator. Create and project a conservative programming base.

Continue this workflow with the IPF GL Points Calculator. Use the official sex, event, and equipment coefficients.

Worked example and training percentages

At 100 kg for 5 reps, Epley gives 116.7 kg. Brzycki gives 100 x 36/(37-5) = 112.5 kg. The 4.2 kg spread is useful evidence that the answer is not exact. Percentage loads should be based on a conservative working max when fatigue management matters.

Safety and scope

A calculated 1RM is not permission to attempt a maximal lift. Technique, equipment, fatigue, injury history and spotting matter. New lifters and people with health concerns should use qualified supervision. RPE, velocity-based data and sport-specific testing may be more appropriate than a generic rep formula.

Formula, precision and QA disclosure

CalculatorGeek normalizes units before applying the named formula, retains working precision through intermediate steps and rounds the displayed result once. Inputs outside the supported domain must return a clear no-result or warning state; they must not be silently forced into a plausible-looking answer.

Choose the next calculator from the Strength Training and Powerlifting Calculators.

Inputs, outputs and result meaning

Calculates estimated one-rep max, imperial equivalent, rounded training load, and training load equivalent from lift type, weight lifted, repetitions completed, and primary estimate with visible method, validation, precision, and limitations.

Inputs

Lift type: Labels the result. No unsupported lift-specific correction factor is applied. Available choices are Not specified, Squat, Bench press, Deadlift, and Overhead press. This field is optional.
Weight lifted: Load completed for the entered repetitions. Supported units include kilograms (kg) and pounds (lb). The supported range is 0.1 through 5,000.
Repetitions completed: Use a technically sound set close to failure. Supported units include reps. The supported range is 1 through 15.
Primary estimate: All seven estimates remain visible in the calculation. Available choices are Seven-formula mean, Epley, Brzycki, Lombardi, Mayhew, Wathan, O'Conner, and Lander.
Training percentage: Percentage for the rounded working load. Supported units include percent (%). The supported range is 40 through 120.
Available load increment: Round to equipment you can load. Supported units include kilograms (kg) and pounds (lb). The supported range is 0.25 through 100.

Outputs

Estimated one-rep max: This is the primary result. It is displayed in kg. The visible value uses up to 1 decimal places according to the output rule.
Imperial equivalent: It is displayed in lb. The visible value uses up to 1 decimal places according to the output rule.
Rounded training load: It is displayed in kg. The visible value uses up to 1 decimal places according to the output rule.
Training load equivalent: It is displayed in lb. The visible value uses up to 1 decimal places according to the output rule.
90% training max: It is displayed in kg. The visible value uses up to 1 decimal places according to the output rule.
Lowest formula estimate: It is displayed in kg. The visible value uses up to 1 decimal places according to the output rule.
Highest formula estimate: It is displayed in kg. The visible value uses up to 1 decimal places according to the output rule.

Seven published prediction equations are calculated from the same load and repetition count. Keep the result label, unit, selected mode, and stated limitations together when sharing the answer.

Frequently asked questions

Which 1RM formula is best?

No equation is universally best; accuracy depends on exercise, reps, effort and population.

How many reps should I use?

A hard set around 2-10 reps is generally more suitable than a high-rep set.

What is a training max?

A deliberately conservative percentage of estimated or tested 1RM used for programming.

Can I calculate 1RM from bodyweight exercises?

Only if total external resistance is defined appropriately; ordinary formulas may not fit.

Should I test a true 1RM?

Not necessarily; submaximal estimates can reduce risk and fatigue.

Primary sources

Implementation validation covers the method, units, source record, and published verification cases. Official or primary sources control where policies or standards change.

NSCA - Essentials and position resources - https://www.nsca.com/education/articles/
ACSM resistance exercise guidance - https://www.acsm.org/education-resources/trending-topics-resources/resource-library/detail?id=1f6122e4-36e2-4aaf-b8df-890fb7e2c8ce