Bumper plates are thick rubber plates made to be dropped from overhead, so they suit Olympic lifting and platforms. Iron plates are thinner and cheaper, fit more weight on the bar, and suit powerlifting, but they should not be dropped. Calibrated plates are precise iron plates used in competition.
What are bumper plates?
- Made of rubber, sometimes around a steel or brass hub
- Diameter of 450 mm for every weight from 10 kg up, so the bar sits at the same height whatever the load
- Built for the snatch, clean and jerk and anything that gets dropped from overhead
- Downsides: they are thick, so you cannot fit as much weight on the bar. A bar loaded with bumpers to a very heavy deadlift can run out of sleeve.
Competition bumpers are thinner and color coded. Training bumpers are often black and thicker.
What are iron plates?
- Made of cast iron or machined steel
- Thinner than bumpers at the same weight
- Cheaper, which is why most commercial gyms use them
- Not built to drop. Even dropping a deadlift a few inches puts stress on them and on the floor. Cast iron can chip and crack.
- Accuracy varies. A cheap "45 lb" plate can be a few pounds off.
Small iron plates, like 10s and 5s, are smaller in diameter than a 45. That matters for deadlifts: with only small plates the bar starts lower, so lighter pulls are deeper unless you set it on blocks or use bumpers.
What are calibrated plates?
Calibrated plates are steel plates machined and weighed so each is within a small tolerance of its labeled weight. Powerlifting federations use them at meets. They are thin, so you can load a lot of weight on the bar, and they follow a standard color code. In the IPF system, 25 kg plates are red, 20 kg blue, 15 kg yellow and 10 kg green.
Training on calibrated plates is not required, but it is useful when you are peaking for a meet and want to know the bar weighs exactly what you think it does.
Kilos or pounds?
Most commercial gyms in the US use pound plates. Many strength gyms in the US and most in Canada have kilo plates, especially if they host meets. A 20 kg plate is about 44 lb, a little lighter than a 45. A 25 kg plate is about 55 lb. If you switch, do the math before you chase a number.
Which plates should you look for at a gym?
- Weightlifting: bumpers and a platform. Without both, you cannot train the lifts properly.
- Powerlifting: iron or calibrated plates, enough to load a heavy deadlift, plus some bumpers for lighter pulls.
- General strength: iron plates are fine. A few bumpers are a bonus.
Can you drop iron plates?
Plate type is usually the first thing a gym looks at when deciding its drop rule. A gym full of iron plates on thin mats will almost always ask you to lower the bar. A gym with platforms and bumpers is more likely to allow drops. Many gyms with both allow drops only with bumpers, only on the platforms, and never with an empty bar. For what chains actually say in writing, see can you drop weights at the gym?
How do you find a gym with bumpers and platforms?
Gyms that have them usually say so on their equipment page or in photos. On Chalkproof, filter for gyms with platforms, or start from powerlifting gyms near me. Our guide to what to look for in a deadlift platform gym has a checklist for the visit.
Common questions
Can you drop iron plates?
You should not. Iron plates are not built for drops, and dropping them can crack the plates and damage the floor. Most gyms with iron plates ask you to lower the bar.
Why do bumper plates all look the same size?
Most bumpers from 10 kg up share a 450 mm diameter, so the bar always starts at the same height. They get thinner or thicker to change the weight.
What are calibrated plates?
Steel plates weighed to a tight tolerance of their labeled weight. Powerlifting meets use them, and they follow a color code.
Are bumper plates good for deadlifts?
They work well for light and moderate deadlifts and protect the floor. For very heavy pulls they take up a lot of sleeve, so iron or calibrated plates fit more weight.