What is the history behind 45 pound plates/bars?

 Why did this become the standard weight for weight bars and heavy plates vs. using 50 pounds or 20 kg (44 pounds) which would have made for easier math?

20kg = 45 lbs

 20 kg = 44 pounds

your plate varies by a pound or two, unless you have super expensive plates... and if you have super expensive plates, they're probably 20kg not 45 lbs.

so 20kg = 45lbs plus or minus 2 lbs

10 kg, 15 kg, 20 kg and 25 kg are the most usual international plates. Black, yellow, blue and red in color...

45 lbs is the equvalent of 20 kg. Eg 5 x 45 225 lbs which equals 100 kg...

Standard olympic size plates are 45lbs or 20.4kgs.

Most plates will be out by 2-7%.

Competition plates are so accurate that if they are off weight by as much as the weight of a quarter (25cents) then they are scrapped.

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 It only seems to be a standard in America. Everyone else uses kgs and hence 20kg bars

And 1kg = 2.204 lb

20kg = 45lbs

krakkerz -  It only seems to be a standard in America. Everyone else uses kgs and hence 20kg bars

And 1kg = 2.204 lb

20*2.204 = 44.08 lbs



But I guess the message is that this is close enough and I suppose 45 is easier to add up than 44 (although less so than 50).

 

Yes But the 20.4 that all 45lb plates weigh are 44.96lbs, not much rounding going on there.

http://www.stacca.com/v/vspfiles/V4_Backup/ProductImages/Landing/Olympic_Plate_Fit.jpg

I will not be ignored!

JasonKeaton - 20kg = 45lbs



Lol. 20KG = 44lbs

At my gym we have both 44lbs plates (20kg) and 45lbs plates.

molsonman - 
JasonKeaton - 20kg = 45lbs



Lol. 20KG = 44lbs

At my gym we have both 44lbs plates (20kg) and 45lbs plates.



Yeah I know.


Everyone kept posting these tings over and over. Wanted to be a part of the group

jeremy hamilton - 

Most plates will be out by 2-7%.

Do you have a source for this?  7% seems really high (about 3 pounds per 45 pound plate).  In the case where you had a light/heavy plate combo you could be off by 6 pounds on a side.  That would seem to be too much not to notice--more than the equivalent of putting a 5 pound plate on one side and not the other.

 

Yes I do. This was stated in Randall Strossens Ironmind book titled Captains Of Crush Grippers: What they are and how to close them. He says it on page 14.

I did get the percentage wrong though, its 5-10% not 2-7 like I thought it was.

Also I have my own evidence. A friend of mine and myself have over 800lbs of weights at his shop. We had to weigh every single plate individually and write the poundage on each so we could be accurate about our lifts.

Do you know what we found? We found that we dont have any 45lb plates. They were everything but 45. Lots of 48s and a couple 49s, even some 42s. Now do you believe me?

What brand of plates are you using? If you are using Werksan or Ivanko than you wont have any problems.

I am talking the old black iron plates. Any gyms I have been in that have new plates seem to be accurate, although I didnt weigh any of them.