To calculate barbell weight, add the weight of the bar itself to the combined weight of all plates loaded on both sides. The formula is simple: bar weight + (weight on left side + weight on right side) = total weight. The part most people get wrong is forgetting to count the bar, which on a standard Olympic barbell is 45 pounds (20 kg).
The Basic Formula
Every barbell calculation has three components: the bar, the plates on one side, and the plates on the other side. Since you should always load both sides equally, the math simplifies to: bar weight + (plate weight per side × 2).
Say you have a 45-pound Olympic bar with a 45-pound plate and a 25-pound plate on each side. That’s 45 + (70 × 2) = 185 pounds total. If someone at the gym tells you they “put two plates on,” they typically mean two 45-pound plates per side, which works out to 45 + (90 × 2) = 225 pounds.
Know Your Bar Weight First
The bar is the piece people most often miscalculate, and not all bars weigh the same. A men’s Olympic barbell weighs 45 pounds (20 kg), measures 7 feet long, and has a 28mm shaft diameter. A women’s Olympic barbell weighs 33 pounds (15 kg) with a thinner 25mm shaft designed for smaller hands. These weights are standardized regardless of manufacturer.
Other bars you’ll encounter in a gym have different weights entirely. EZ curl bars (the shorter, zigzag-shaped bars for bicep curls) typically weigh between 15 and 25 pounds depending on the model. Trap bars, the hexagonal frames you stand inside for deadlifts, usually run 45 to 65 pounds. Safety squat bars with the padded yoke tend to weigh around 60 to 70 pounds. Aluminum technique bars, used for learning form or warming up, weigh as little as 15 pounds.
If you’re unsure what a bar weighs, check the end cap for a stamped weight, look it up by brand, or simply weigh it on a scale. Getting this number wrong throws off every calculation you make.
Standard Plate Sizes
Plates come in predictable denominations. In pounds, the most common are 2.5, 5, 10, 25, 35, and 45. In kilograms, you’ll find 1.25, 2.5, 5, 10, 15, 20, and 25. Kilogram plates at competition-level gyms are color-coded: red for 25 kg, blue for 20 kg, yellow for 15 kg, green for 10 kg, white for 5 kg, and black for 2.5 kg. Smaller change plates of 1.25, 0.5, and 0.25 kg are typically chrome.
At most commercial gyms in the U.S., plates are labeled in pounds and are all the same color (usually black or gray iron). Read the number stamped or printed on each plate before loading it. Worn plates can be hard to read, and grabbing a 35 when you meant to grab a 25 adds 20 unexpected pounds to your lift.
A Step-by-Step Example
Here’s the process broken down. Say you’re setting up a barbell for squats and you want to lift 225 pounds.
- Start with the bar: A standard men’s Olympic bar is 45 lbs.
- Subtract the bar from your target: 225 − 45 = 180 lbs of plates needed.
- Divide by two (since plates go on both sides): 180 ÷ 2 = 90 lbs per side.
- Choose your plates: One 45-lb plate and two 25-lb plates on each side, or two 45-lb plates on each side. Both combinations equal 90 per side.
To check your math, work backward: 45 (bar) + 45 + 25 + 25 (left side) + 45 + 25 + 25 (right side) = 235. That’s wrong, so you adjust. Two 45-lb plates per side: 45 + 45 + 45 + 45 + 45 = 225. That checks out.
The Kilogram-to-Pound Rounding Issue
If you train at a gym with kilogram plates but think in pounds (or vice versa), the conversion creates a small but real rounding quirk. One kilogram equals 2.205 pounds, so a 20 kg bar actually converts to 44.1 pounds, not exactly 45. A 25 kg plate converts to 55.1 pounds, not a round number.
In practice, most lifters round 20 kg to 45 lbs and don’t worry about the fraction. But if you’re logging lifts precisely or comparing numbers between a kilogram gym and a pound gym, use the USA Powerlifting conversion: multiply kilograms by 2.205. A 100 kg total is 220.5 lbs, not 220. A 60 kg total is 132.3 lbs. The difference grows as the weight goes up. At 200 kg, you’re looking at 440.9 lbs, nearly a full pound under what you’d get rounding each plate individually.
Do Collars Count?
Standard spring clips, the simple metal clamps most people use, weigh next to nothing and can be ignored. Competition collars are a different story. Rogue’s competition collars, for example, weigh 2.5 kg each (5 kg total for the pair), adding about 11 pounds to your barbell. In official powerlifting and weightlifting competitions, these collars are part of the declared total. If you’re training with heavy competition collars, factor them in. If you’re using basic spring clips or plastic clamps, skip them.
Calculating for Smaller Increments
Most gyms jump in 5-pound increments at minimum (a 2.5-lb plate on each side). If you want to progress in smaller steps, fractional plates let you add as little as 0.25 lbs per side, making your smallest possible jump 0.5 lbs total. Sets typically include pairs of 0.25, 0.5, 0.75, and 1-lb plates.
The math works the same way. If you benched 185 lbs last week and want to try 186.25, you’d load your bar to 185 and add a 0.625-lb fractional plate to each side. These micro-jumps are especially useful for upper-body lifts where a full 5-pound jump can stall progress.
Quick Reference for Common Totals
These assume a standard 45-lb Olympic bar:
- Bar only: 45 lbs
- One 25 per side: 95 lbs
- One 45 per side (one plate): 135 lbs
- One 45 + one 25 per side: 185 lbs
- Two 45s per side (two plates): 225 lbs
- Three 45s per side (three plates): 315 lbs
- Four 45s per side (four plates): 405 lbs
When lifters say they “bench two plates” or “squat three plates,” these are the numbers they mean. Each “plate” in gym shorthand refers to a 45-lb plate per side.