About GymCalc

Training is full of small, repetitive math problems. What's my max? Which plates make 100 kg? What pace gets me under 50 minutes for a 10K? What size does this tape measurement translate to? Each calculator here answers one of those questions with plain arithmetic, and the answer updates as you type.

Nothing to install, no account, no submit button. The whole site is a handful of small pages that work the moment they load.

The Calculators

One rep max

The 1RM calculator runs your set through Epley, Brzycki and Lombardi, shows all three answers plus their average, and converts the result into a 50 to 95 percent training table.

Plate loading

The plate calculator splits a target across a barbell, picks plates greedily from heaviest to lightest, and draws the loaded bar so you can match it at a glance.

Running pace

The pace calculator solves whichever of distance, time or pace you leave open, with presets from 5K to marathon and a km/mile switch.

Bra size

The bra size calculator maps underbust and bust inches to a US band and cup using the modern measured-band convention.

What the Results Are

Estimates, in the honest sense of the word. Formulas like Epley and Brzycki describe population averages, plate math assumes a standard rack, and clothing sizes shift between brands. Use the output as a starting point and let real-world feedback tune it. None of it is medical, coaching or fitting advice; the disclaimer spells that out.