How the plate math works
The bar is part of the total, and plates load in matching pairs. That makes the arithmetic the same three steps every time: subtract the bar from your target, halve what is left, and load that on one side. For 100 kg on a 20 kg bar you have 80 kg of plates to split, so 40 kg per side, which is a 25 and a 15.
From there you fill each side heaviest first. Starting with the big plates keeps the count low, keeps the load close to the sleeve collar where it belongs, and means the change plates only ever handle the remainder.
When the rack is missing plates
Most gyms are short of something. Turn off any denomination that is not on the rack and the calculator works with what is left, so the number on screen is a bar you can actually build. It always lands at or below your target, never above, because a heavier bar than planned is the one surprise nobody wants under the rack.
If you are looking at a loaded bar instead of an empty one, switch to Count plates and tap what you can see on one side. The calculator doubles it, adds the bar, and gives you the total without you doing the sum mid set.
How much does the bar weigh?
The bar counts toward every number on this page, so it is worth knowing which one you picked up.
| Bar | Kilograms | Pounds | Where you see it |
|---|---|---|---|
| Standard | 20 kg | 45 lb | The default in almost every gym, and the one the calculator assumes. |
| Short | 15 kg | 35 lb | Shorter, with a thinner grip. Standard on the women's platform. |
| Trap | 25 kg | 55 lb | Hex or trap bar. Heavier because you are lifting the frame too. |
| EZ curl | 7.5 kg | 15 lb | Curl bar. These vary a lot, so weigh yours if you can. |
If your bar is none of these, weigh it once and switch the calculator to Custom. Specialty bars such as safety squat and cambered bars run anywhere from 25 kg to 45 kg, and guessing costs you more than a trip to the scale.
Common barbell loads
When lifters count in plates they mean the big ones, 20 kg or 45 lb, one per side at a time. So three plates is 315 lb, and the bar is always part of the number.
| Plates per side | Total with 45 lb plates | Total with 20 kg plates |
|---|---|---|
| Empty bar | 45 lb | 20 kg |
| 1 plate | 135 lb | 60 kg |
| 2 plates | 225 lb | 100 kg |
| 3 plates | 315 lb | 140 kg |
| 4 plates | 405 lb | 180 kg |
| 5 plates | 495 lb | 220 kg |
| 6 plates | 585 lb | 260 kg |
| 7 plates | 675 lb | 300 kg |
| 8 plates | 765 lb | 340 kg |
The two columns are not conversions of each other. A 45 lb plate is a little lighter than a 20 kg plate, so a four plate squat is 405 lb in one gym and 180 kg in another.
What the plate colors mean
Competition plates follow a fixed color code, which lets you read a loaded bar from across the room instead of squinting at the numbers.
| Color | Kilograms | Pounds | Notes |
|---|---|---|---|
| Red | 25 kg | 55 lb | The small 2.5 kg change plate is red too. |
| Blue | 20 kg | 45 lb | The plate lifters are counting when they say one plate. |
| Yellow | 15 kg | 35 lb | 1.5 kg repeats the color at a tenth of the weight. |
| Green | 10 kg | 25 lb | 1 kg repeats the color at a tenth of the weight. |
| White | 5 kg | 10 lb | 0.5 kg repeats the color at a tenth of the weight. |
| Chrome | 1.25 kg | 2.5 lb | Bare steel change plates, outside the color code. |
The code repeats at a tenth of the weight, which is why red is both 25 kg and 2.5 kg. Rubber bumpers in a commercial gym often ignore all of this and arrive in one color, usually black, so read the number stamped on the face.
Know what to load, then know how much to lift
This calculator answers the last question of the set up: which discs go on the bar. The other two tools handle the number itself, whether you are working from a tested max or from how the last set felt.
Frequently asked questions
How do you calculate plates on a barbell?
Subtract the bar weight from your target, then divide by two to get the load for one side. Fill that side starting with the heaviest plate you have. For 100 kg on a 20 kg bar that is 40 kg per side, which comes out as a 25 and a 15.
How much does a barbell weigh?
A standard Olympic bar is 20 kg, sold as 45 lb. Shorter bars are usually 15 kg or 35 lb, trap bars tend to sit around 25 kg, and EZ curl bars are roughly 7.5 kg. Specialty bars vary enough that it is worth weighing yours once.
How do I count the plates already on the bar?
Switch to Count plates mode and tap each plate you can see on one side. The calculator doubles that side and adds the bar, so you get the total without counting in your head between sets.
What if the exact weight cannot be loaded?
You get the closest weight your plates can build at or below your target. If the gap is bigger than you would like, turn the small change plates back on, or check whether the rack has a pair you missed.
What do the plate colors mean?
Competition plates are color coded by weight: red 25 kg, blue 20 kg, yellow 15 kg, green 10 kg, white 5 kg. The code repeats at a tenth of the weight, so the small red change plate is 2.5 kg. Pound plates in competition mirror the same colors at 55, 45, 35, 25 and 10 lb.
Why does the calculator never go over my target?
Because an unexpectedly heavy bar is the one error that costs you a rep or a rep range. Rounding down keeps every result a weight you planned to lift, and the note tells you exactly how far under your target it landed.