Bench Press Calculator — 1RM Estimator | CalcsDone

Strength Training

Bench Press Calculator

This bench press calculator estimates your one-rep max (1RM) from the weight and reps of a recent set, then uses the built-in percentage chart to plan warm-ups, working sets, and training blocks.

Built and maintained by Umer Farooq, Founder & Developer, CalcsDone

Last updated: September 19, 2026

Enter Your Set

Formula: Epley — w × (1 + r/30)

Units

Formula

Weight lifted

Reps performed

reps

Common rep counts

Estimated 1RM

0 lb

90% of 1RM

0 lb

75% of 1RM

0 lb

Enter a weight and rep count to estimate your one-rep max

1RM estimate by formula

Formula	Estimated 1RM
Enter a weight and reps above to compare formulas.

Unit note: Switching between lb and kg converts the entered weight so the same load is preserved.

Training estimate only. Prediction equations can differ from a measured 1RM, and accuracy varies with exercise, repetition count, training status, technique, and fatigue. Use a recent technically sound set and treat higher-repetition estimates with extra caution. This tool is not medical advice or a substitute for qualified coaching when you need individualized exercise guidance. Values entered into these calculator fields are processed in your browser and are not submitted by this calculator to CalcsDone.

% of 1RM	Weight	Typical use

Why use this calculator

Why a bench press calculator beats guessing your max

A measured one-repetition maximum requires a maximal effort and appropriate technique, setup, and safety precautions. A repetition-based equation offers a practical alternative when you want a planning estimate from a submaximal set. Epley, Brzycki, and Lombardi use the lifted weight and completed repetitions to produce different estimates; research shows prediction accuracy varies by equation, exercise, population, and repetition range.

This bench press calculator can show Epley, Brzycki, and Lombardi estimates separately or display their simple arithmetic average. The percentage chart then converts the selected estimate into reference loads. These percentages are planning references rather than individualized prescriptions.

How it works

How the bench press calculator works

This bench press calculator uses patterns observed across many lifters to estimate your true max from a lighter set taken near failure, rather than measuring it directly.

Epley formula

1RM = w × (1 + r/30). A commonly used repetition-based 1RM prediction equation.

Brzycki formula

1RM = w × 36 / (37 − r). Another commonly used equation for estimating 1RM from a repetition-to-fatigue set.

Lombardi formula

1RM = w × r^0.10. A power-function equation that can produce a different estimate from Epley or Brzycki.

Why formulas disagree

The equations use different mathematical relationships, so their estimates can diverge as repetition count changes. Research on repetition-based prediction also shows that accuracy depends on the exercise, population, and repetition range. Compare the outputs rather than treating any one equation as an exact measurement.

Worked examples

See how the calculator works

These realistic training examples use the same formulas as the calculator. They are illustrative sets, not claims about a particular athlete’s verified performance.

Example 1

Heavy set (lower reps)

A realistic strength-focused set using the Epley equation.

Inputs

Weight lifted185 lb

Repetitions5

FormulaEpley

Results

Estimated 1RM≈ 216 lb

90% of estimate≈ 194 lb

75% of estimate≈ 162 lb

Key takeaway185 lb for 5 reps produces an Epley estimate of about 216 lb. The result is a planning estimate, not a measured maximum.

Example 2

Moderate set (mid reps)

Compare all three prediction equations from the same set.

Inputs

Weight lifted135 lb

Repetitions8

Comparison3 formulas

Results

Epley≈ 171 lb

Brzycki≈ 168 lb

Lombardi≈ 166 lb

Key takeawayThe three equations produce estimates spanning about 5 lb in this example, showing why an estimated 1RM is better treated as a range than an exact measurement.

Example 3

Higher-rep set

A higher-repetition example where equation outputs separate more.

Inputs

Weight lifted95 lb

Repetitions15

Comparison3 formulas

Results

Epley≈ 142.5 lb

Brzycki≈ 155.5 lb

Lombardi≈ 124.5 lb

Key takeawayThe spread is about 31 lb here. Higher-repetition predictions can vary more, so use extra caution when interpreting them.

About these examples: The inputs are realistic illustrative bench-press sets, and every displayed result is calculated directly from the Epley, Brzycki, or Lombardi equation used by this page. They are not fabricated testimonials or athlete performance claims.

Common mistakes & edge cases

Where 1RM estimates go wrong

Using a set that wasn’t close to failure

Repetition-to-fatigue equations are most directly interpreted when the repetition count reflects the number you could actually complete at that load. If you stop well before your repetition limit, the resulting estimate can understate your maximum.

Trusting high-rep estimates as precisely as low-rep ones

Prediction accuracy is not constant across repetition ranges, and different equations can diverge more as repetitions increase. Treat higher-repetition estimates as approximate and compare formulas when useful.

Programming percentages off a stale 1RM

Strength performance changes with training status, fatigue, technique, and other conditions. If you use percentage-based loads, base them on a reasonably current estimate and adjust training to actual performance.

Ignoring technique breakdown at heavier percentages

An estimated 1RM is not a guarantee that a particular load can be lifted safely or successfully. Technique, fatigue, equipment, training experience, and individual circumstances still matter.

Mixing lb and kg inputs without converting

The unit toggle switches the display, but the input weight still needs to match whichever unit is selected. Enter a kg figure while “lb” is active, or vice versa, and every percentage below it will be off.

FAQ

Common questions

How accurate is an estimated 1RM?+

An estimated 1RM can be useful for planning, but there is no single accuracy percentage that applies to every lifter. Studies show error varies with the equation, exercise, population, and repetition range. Treat the result as an estimate rather than a measured maximum.

Which formula should I use?+

No equation is universally best for every lifter or exercise. This calculator lets you compare Epley, Brzycki, and Lombardi. The “average” option is simply the arithmetic mean of those three estimates; it is not a separately validated prediction equation.

How do I use the percentage chart?+

The chart converts the selected estimated 1RM into reference loads. Training goals are not determined by percentage alone: current ACSM guidance emphasizes heavier loads for maximizing strength, while hypertrophy is influenced strongly by training volume and can occur across a broad range of loads. Use the chart as a planning reference, not a complete program.

Should I actually test my true 1RM?+

Whether to test a true 1RM depends on training experience, technique, health, equipment, supervision, and goals. If you are inexperienced with maximal lifting or have a health or injury concern, seek appropriate professional guidance rather than using this calculator as clearance to attempt a maximum.

Does this work for other lifts besides bench press?+

The equations are also used with other resistance exercises, but their prediction error can vary by exercise and population. A result from this page should therefore be treated as an exercise-specific estimate rather than assumed to have identical accuracy for every lift.

Why do my 1RM estimates change slightly between formulas?+

Each equation uses a different mathematical model, so the same weight-and-repetition set can produce different estimates. None should be treated as a universally exact measurement; comparing the outputs makes that uncertainty visible.

Related calculators

Continue your strength-training calculations

Use these related CalcsDone tools for additional training estimates and reference calculations.

Sources & methodology

Formula references

Brzycki M. Strength Testing — Predicting a One-Rep Max from Reps-to-Fatigue. Journal of Physical Education, Recreation & Dance, 64(1), 88–90 (1993). Original publication of the Brzycki formula (1RM = w × 36 / (37 − r)).
LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. The Accuracy of Prediction Equations for Estimating 1-RM Performance in the Bench Press, Squat, and Deadlift. Journal of Strength and Conditioning Research, 11(4), 211–213 (1997). PMID: 9355611. Peer-reviewed comparison of several prediction equations for estimating 1RM performance, including bench press.
Epley B. Poundage Chart. Boyd Epley Workout, Body Enterprises (1985). Historical source associated with the Epley formula; the equation is also discussed in later 1RM prediction research.
Lombardi VP. Beginning Weight Training: The Safe and Effective Way. Wm. C. Brown Publishers (1989). Historical source associated with the Lombardi formula; the equation is also discussed in later 1RM prediction research.
National Strength and Conditioning Association (NSCA). Training Load Chart. NSCA training-load reference. Percentage-based loads are shown here as planning references rather than a complete training prescription.
American College of Sports Medicine (ACSM). Resistance Training Guidelines Update (2026). Current evidence-based context for resistance-training load, volume, strength, hypertrophy, and power programming.
CalcsDone Methodology How calculator formulas, assumptions, sources, limitations, and updates are handled across CalcsDone.