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

Editorial review pending Updated Jul 2026 Used 0 times
Load completed for the entered repetitions.
Use a technically sound set close to failure.
All seven estimates remain visible in the calculation.
Percentage for the rounded working load.
Round to equipment you can load.

Guest calculations stay on this device. Signed-in results sync privately.

Your result

Estimated One-Rep Max

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

One-rep-max comparisonThe selected method is shown beside two established formula comparisons.
Selected 1RM estimatePrimary result —
Epley comparisonComparison estimate —
Brzycki comparisonComparison estimate —
FormulaVersioned calculationv3.2.0

What is calculated

The selected prediction method estimates the displayed result.

Legacy behavior retained

Epley and Brzycki, training percentage table, load rounding.

Important limitation

Rebuilt from the live implementation and premium package. Project-specific assumptions remain editable and visible.

Transparent by design

CalculatorGeek quality standard

MethodSeven published prediction equations are calculated from the same load and repetition count.
ImplementationRebuilt in the shared schema from the live tool and premium content package.
Verification2 published calculation and boundary cases.
Review statusPASS WITH WARNINGS - implementation QA completed September 11, 2026.
Result actions Compare
1
Enter a rep setUse a technically sound set within 1 to 12 repsAvoid unsupported high-rep prediction
2
Apply the selected equationKeep the method visibleEpley or Brzycki
3
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.

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

Use this result

Keep exploring

4 available tools
1RM Percentage ChartTurn a max into exact and loadable percentage targets.Barbell Plate CalculatorBuild a balanced plate setup from real inventory.Training Max CalculatorCreate and project a conservative programming base.Strength Training and Powerlifting CalculatorsChoose the right strength, loading, or scoring tool for the next decision.
Public verification recordFormula v3.2.0
Review 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.
Review team
CalculatorGeek Algorithmic Team
Verified
2026-09-08
Next source review
2027-09-08
Automated fixtures
2 cases

Review method

Content package, legacy implementation, formulas, units, boundary behavior, sources, and fixtures are reviewed separately before release.

Known limitations

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

Primary sources

Latest update

2026-09-16 · Connected the verified strength and powerlifting cluster and removed links to unavailable placeholder routes.

Published calculation checks

CaseInputsExpected result
Seven-formula five-rep meanepley=116.6666667, brzycki=112.5, lombardi=117.4618943, target_load=92.5, classification=high_confidence
One rep identityone_rm=102.05828325, low_estimate=102.05828325
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.

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.

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.

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.

Sources and review

Prepared for CalculatorGeek on September 8, 2026. Before publication, the CalculatorGeek Algorithmic Team must verify the live implementation, replace any deployment placeholders and set the visible review date. Official or primary sources control where policies or standards change.