How it works
Take the bar weight off your target, halve what's left — that's the load per side. Then fill it from the biggest plate down: as many of the largest plate as fit, then the next size, and so on. That's all the calculator does, with the plates you've ticked, and it draws the result so you can match it to the bar in front of you.
If the exact weight can't be made with your plates, it loads the closest weight underneath and tells you the gap. In practice you either take that weight or borrow a small plate from the next rack.
Worked example (kg): target 100 kg on a 20 kg bar. 100 − 20 = 80, so 40 kg per side. That's one 25 and one 15 — or, if there are no 15s, a 25, a 10 and a 5. The drawing shows whichever matches what you ticked.
Worked example (lb): target 225 lb on a 45 lb bar. 225 − 45 = 180, so 90 per side: two 45s. The classic "two plates".
FAQs
Is this plate calculator free?
Yes. No account, no email, no paywall. It runs in your browser and nothing you enter is stored or sent anywhere. trainerX makes the iPhone app that tells you what to lift each session; the calculator is free whether or not you use the app.
How much does a barbell weigh?
A standard Olympic men's bar is 20 kg (45 lb in US gyms, which is 20.4 kg). The women's Olympic bar is 15 kg (35 lb). Shorter training bars are often 10 kg or 15 lb, and some specialty bars (safety squat, trap bar) weigh 25–30 kg — check the end cap or ask. The calculator lets you set any bar weight.
Do I count the collars?
Spring clips and plastic clamps weigh so little (about 0.1–0.25 kg each) that most people ignore them. Competition collars are 2.5 kg each and do count — if your gym uses them, add 5 kg to the bar weight.
What if I can't make the exact weight?
The calculator loads the closest weight you can reach with the plates you have and tells you how far short it is. Most of the time the right move is to take the nearest loadable weight; a 1.25 kg or 2.5 lb plate per side is the smallest jump in most gyms. Untick plates you don't have so the result matches your rack.
Which order do plates go on?
Heaviest first, closest to the collar, then smaller plates on the outside, so the load sits near the bar's centre and the bar bends evenly. Load both sides evenly as you go — one plate each side at a time for heavy weights — so the bar doesn't tip off the rack.
Why do plates have colours?
International competition plates are colour-coded by weight: 25 kg red, 20 kg blue, 15 kg yellow, 10 kg green, 5 kg white, with 2.5 kg red and 1.25 kg chrome. The drawing uses the same scheme (and the matching convention for pounds) so you can read the bar at a glance, even if your gym's plates are all black.