Formcast Fitness Free tools

Free tool

Barbell plate calculator

Enter the weight you want on the bar. Get the plates to load on each side, heaviest first, in pounds or kilos. It rounds down rather than handing you an overloaded bar.

Units

Load per side—lb each side

    Plate maths where you actually need it

    In Formcast Fitness the plate calculator sits on the exercise card, pre-filled with the weight you are about to lift — alongside the rest timer, warm-up ramp and automatic PR detection.

    Download on the App Store

    iPhone only · free trial · subscription after the trial

    How this calculator works

    This page runs the plate maths from src/services/plateMath.ts in the Formcast Fitness app, ported function for function. Load the bar the way this page tells you and the app's own plate calculator will tell you exactly the same thing.

    The method

    Subtract the bar, halve what is left, then fill that half greedily from the heaviest plate down. Greedy is optimal here because every denomination divides cleanly into the ones above it, so there is never a case where taking the biggest plate first strands you.

    Internally the arithmetic runs in integer quarter-units (everything multiplied by four) rather than in decimals. That sounds fussy, but 2.5 and 1.25 cannot be represented exactly in binary floating point, and without the integer trick a 142.5 kg target can silently come out one 1.25 kg plate light.

    It always rounds down

    If your target is not reachable with the available plates, you get the closest loadable weight below it, and the page tells you how far short it is. That is deliberate: being handed a bar heavier than you asked for, mid-session, under a rack, is worse than being handed one that is 2.5 lb light.

    What it assumes

    • Plate inventory. Pounds: 45, 35, 25, 10, 5 and 2.5. Kilograms: 25, 20, 15, 10, 5, 2.5 and 1.25. These are the denominations the app assumes. There is no 55 lb or 100 lb plate, no 1.25 lb plate, and no fractional/micro plates.
    • Unlimited plates. It will happily tell you to load four 45s a side. It does not know your gym only owns six of them, and it does not check whether they physically fit on the sleeve.
    • Bar weights. Pounds: 45 (standard), 35 (women's/technique), 15 (training). Kilograms: 20, 15, 10. Same options the app offers.
    • Collars weigh nothing. Competition collars are 2.5 kg each — 5 kg on the bar — and are not counted here. Neither is a bar that has drifted from its nominal weight, which is common on old gym bars.
    • The bar is loaded evenly. Everything shown is per side. Double it, plus the bar, to get the total.

    Switching units converts your target and then snaps it to the nearest loadable step in the new unit (5 lb or 2.5 kg — a pair of the smallest plates), because 225 lb is 102.06 kg and no gym has a plate for the 0.06.

    More free calculators

    All four use the same code the Formcast Fitness app uses, so the numbers match what you would see in the app.