Barbell Weight Calculator

Subtract the bar (and collars) from your target, split what's left in half, then load each side with the fewest plates that add up to it — and if your plates can't hit the number exactly, this tool shows the nearest weights they can.

How the Plate Math Works

Weight per side = (target − bar − collars) ÷ 2. Because both sides of the bar must carry identical plates, everything is solved for one side and then mirrored. The calculator doesn't simply grab the heaviest plate over and over: it searches every combination of the plate sizes you've ticked and picks the one that reaches the per-side figure with the fewest plates. That matters when a size is missing. If your gym has no 45s, for instance, 70 lb per side is best loaded as two 35s — a strict heaviest-first rule would reach for a 35, then a 25 and a 10, three plates instead of two. When no combination lands exactly on the target (say you want 137 lb with 2.5 lb as your smallest plate), you'll get the closest achievable weights just below and just above it.

Worked Example: 225 lb and 185 lb on a 45 lb Bar

For 225 lb: (225 − 45) ÷ 2 = 90 lb per side, which is two 45 lb plates on each side — the classic "two plates" load. For 185 lb: (185 − 45) ÷ 2 = 70 lb per side, loaded as one 45 and one 25. In kilograms, 100 kg on a 20 kg bar gives (100 − 20) ÷ 2 = 40 kg per side: a 25 plus a 15. Add competition collars (2.5 kg each, 5 kg for the pair) and the same 100 kg becomes 37.5 kg per side: 25 + 10 + 2.5.

Frequently Asked Questions

Is a 20 kg bar the same as a 45 lb bar? Not quite. 20 kg is about 44.1 lb, so a kilo bar loaded with pound plates (or the reverse) will be slightly off from the number you think you're lifting. Pick the bar you're actually using and the calculator converts it into your chosen unit.

Should I count the collars? Spring clips weigh so little that most people ignore them. Competition-style locking collars are a different story: under weightlifting and powerlifting rules they're 2.5 kg each, so enter 5 kg for the pair if you use them.

How do I work out what someone else left on the bar? Switch to "Total weight of a loaded bar", enter how many of each plate sit on one side, and the calculator doubles it and adds the bar and collars.

Limitations

The result assumes plates weigh exactly what's printed on them. Calibrated competition plates are held to tight tolerances, but cheap cast-iron plates can be off by a few percent, and bar weights vary more than people expect — some "45 lb" bars in commercial gyms weigh 44 or 46. Also note the calculator assumes you have as many of each plate as you need; if you only own one pair of 45s, check the plate count in the breakdown before loading.