✦ Wellness with Emily · Free strength tool

One Rep Max Calculator

Estimate your one-rep max from a completed set, explore training loads, build a barbell plate plan, and track strength over time — without needing to test your absolute maximum.

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Calculate your estimated 1RM

Choose an exercise and enter the weight and reps you completed with controlled technique.

Exercise

Exercise name (optional)

Weight lifted (kg)

Reps completed

Reps left in reserve (estimated)

A set stopped early can underestimate your max. Reps in reserve (RIR) is subjective, so this adjustment is approximate. You don’t need to train to failure to use the tool.

For adults using resistance training. A predicted 1RM is a planning estimate, not a safe invitation to attempt a maximal lift. Use appropriate technique, spotters and equipment.

Understand your result

Train smarter, not just heavier.

A consistent submaximal set can be more useful for everyday training than testing a personal record.

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Your estimate, not a guarantee

The same lift can produce different estimated maxes depending on formula, technique, fatigue, and how close the set was to your limit.

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Comparable sets reveal trends

Track the same exercise and a similar effort level to see whether your estimated strength is changing.

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Percentages are starting points

Use estimated training loads alongside perceived effort or repetitions in reserve, rather than following a fixed rep chart.

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Technique and recovery come first

Work within your ability. Beginners and people with relevant health concerns may benefit from qualified coaching.

The Epley equation is used for the headline estimate. Other formulas are shown to illustrate how predictions differ.

Your strength snapshot

SQUAT · ESTIMATED 1RM

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Epley formula

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Weight lifted

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Reps completed

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Approx. % of estimated 1RM

Compare estimation formulas

None of these is an exact measurement. The spread is informative, not a clinical confidence interval.

Epley: weight × (1 + effective reps ÷ 30), with the completed weight used for a one-rep set with zero RIR. Other published formulas use different curves. Predictions are generally less reliable for higher-rep sets.

Training-load reference

These are percentages of your estimated 1RM. They are load references, not guaranteed rep ranges or recommended prescriptions.

% of 1RM	Estimated load	Use as

Higher loads often suit low-rep practice; lighter loads may suit more repetitions. Actual effort depends on your training history, exercise, and remaining reps.

Barbell plate planner

Choose an illustrative target percentage and find a practical plate setup. Use pairs of plates, one plate of each size on each side.

Target load

Empty bar weight (kg)

Common plate sizes assumed: 25, 20, 15, 10, 5, 2.5, 1.25 kg (or 45, 35, 25, 10, 5, 2.5, 1.25 lb). Your gym may have different plates.

Your saved strength history

Save individual sets when you want to compare progress. Up to 40 entries stay in this browser only, unless you clear them.

Show exercise

The trend chart shows the Epley estimate for the selected exercise. Compare similar efforts and rep ranges for a more meaningful trend.

No saved lifts yet. Calculate a lift, then choose “Save this lift.”

What does one-rep max tell you?

One-repetition maximum (1RM) is the greatest weight a person can lift once for a particular movement using a defined technique. An estimated 1RM uses a submaximal set and a mathematical equation instead of a true maximum test.

A set with 3–8 controlled repetitions may provide a useful estimate when performed near your actual repetition limit, but exercise selection, training experience, fatigue, and reps in reserve matter. Different formulas can give different answers for the same set.

You do not need to lift your predicted maximum to train effectively. Try manageable loads, maintain good technique, and adjust based on how hard each set feels.

Using estimated training loads

Percent-of-1RM tables are useful for comparing relative loads, but they do not tell everyone exactly how many reps they should do. Recent resistance-training guidance emphasizes individualization, training goals, and how close a set comes to failure.

If a load feels unexpectedly difficult, reduce it. If you can repeat the same set with excellent technique and more repetitions comfortably available, you can gradually progress the load or reps.

Safety: Avoid abrupt load jumps, especially in the squat, deadlift, bench press, and overhead press. Use suitable equipment and a spotter where appropriate.

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Methodology and references

Formula examples reflect commonly used prediction equations. Their errors differ by exercise and population; the results here are not direct strength tests. Training percentages are examples for planning, not a substitute for coaching.

References: 2025 cross-validation of 1RM equations (JSCR) · 2026 ACSM resistance-training position stand. For adults only. This tool does not provide medical or individual training prescriptions. Browser saving is device-specific and may not be available in private browsing.