How to use
Use a bench press set you have already recorded to estimate the load for one repetition. This page is for reading and comparing a training log, not for prescribing a maximum attempt. The result is an estimate derived from weight and repetitions; it is not a measurement of what you can lift today.
- Select kilograms or pounds. Enter the total external barbell load, including the bar and plates on both sides.
- Enter the number of complete repetitions from one set, from 1 to 10. The equation assumes a set at or near your repetition limit; it does not ask you to perform a new test.
- Press Calculate to display the estimated 1RM and its percentage table. Read the unit beside every weight.
- Copy result includes the estimate, table and limitation note. Editing either input invalidates the old result. Clear removes the recorded inputs and output while retaining the unit.
The Brzycki estimate
The implemented equation is weight ÷ (1.0278 − 0.0278 × repetitions), using the decimal coefficients published for Brzycki’s 1993 method. At one repetition the result equals the entered load. More repetitions at the same load produce a higher estimate within the supported range.
Only 1–10 whole repetitions are supported. Extending the equation to high repetition sets can produce a misleading number, so this interface rejects them rather than extrapolating. If your recorded set stopped well before your limit, the formula has no information about the unused repetitions. It may understate your capacity.
The formula uses the same unit as the entered load. It contains no bodyweight, age, sex, bar path, equipment or fatigue adjustment. A paused competition bench and a touch-and-go gym set may be different performances even when their entered numbers match. Keep the execution and recording conditions consistent when comparing estimates over time.
Examples you can reproduce
100 kg for 5 repetitions gives 112.51 kg estimated 1RM. The 80% row is 90.01 kg and the 50% row is 56.26 kg. These use the unrounded estimate, not 112.51 as an intermediate input.
80 kg for 10 repetitions gives 106.7 kg estimated 1RM. A separate example of 100 kg for one completed repetition returns 100 kg. Entering 11 repetitions instead produces an input error.
Reading the percentage table
The table lists 100% down to 50% in five-percentage-point steps. Each value is estimated 1RM × percentage ÷ 100. It does not predict how many repetitions you can complete at that percentage, and it does not choose a working weight or round to the plates you own.
Use the table as arithmetic context when comparing a log or discussing an existing program. The numbers are not instructions to load a bar. Load increments, spotting, technique and whether to attempt a lift are outside this calculator. Decimal point or comma is accepted; omit thousands separators and unit text from numeric fields. Weights must be positive and no more than 1,000 kg or the equivalent in pounds. That upper input limit is not a target or recommendation.
Frequently asked questions
Is this a measured one-rep max?
No. A repetition-based formula predicts a value from one recorded set. Day-to-day readiness, technique and individual repetition capacity can differ.
Should I include the bar?
Yes. Enter total barbell weight, not the plate weight on one side. Do not add bodyweight.
Why only one formula?
A named, transparent Brzycki estimate keeps this bench calculator easy to interpret. It does not combine competing formulas into an unsupported confidence range.
Does changing kg to lb change my estimated strength?
No. Existing loads are converted using 1 lb = 0.45359237 kg. The old confirmed output is cleared until you calculate again.
Why do displayed percentages differ slightly from hand calculations?
The table uses the full internal estimate, then rounds each displayed load to at most two decimals. Multiplying a rounded display can differ in the final digit.