Draw weight calculation.

[bihunter]

If a bow is rated at 42"@28" about how much draw weight is lost at 26" draw?

[fnshtr]

I've always heard an estimate of 2-3 lbs. per inch loss. Probably many factors that determine that though.

A bow scale would be the most accurate way to determine it.

Someone else may have a better answer.

[pavan]

My wife's 42@28 NAT pulls exactly 38 at 26".   I had a Tim Miegs that was marked 51@26, it actually pulled 52@26, but was just barely under 51@25 and 53&1/4 @ 27.  That bow a real definite snooze in it. 

[Orion]

Given that it's a rather low draw weight bow, the change per inch is probably close to 2#.  Thus, about 38#@26.

[stevem]

Try this to determine weight loss per inch-
Start with draw weight at 28", then divide by result of subtracting brace height from 28".  Example-
42# divided by 28" - 7" = 42/21 = 2.0#/inch.  So at 26" multiply 2.0 #/inch by 2 inches = 4 pounds loss.

[bihunter]

Thank you for the replies.

[pdk25]

Try this to determine weight loss per inch-
Start with draw weight at 28", then divide by result of subtracting brace height from 28".  Example-
42# divided by 28" - 7" = 42/21 = 2.0#/inch.  So at 26" multiply 2.0 #/inch by 2 inches = 4 pounds loss.

This is how I estimate it as well.  Just usually assume close to 8" brace, then divide draw wt at 28" by 20.  As long as you are close to linear on the force-draw curve, you should be close.

[KAZ]

I have always estimated 5% per inch loss or gain from a known weight/length and it’s been pretty accurate.... Originally received this method from Black Widow Bows.

So (42lbs @28) x .95 = (39.9lbs @27) x .95 = (37.905lbs @26” Draw)

This by no means is perfect for all bow designs, lengths, draw force curve, efficiencies, etc.. but it is a good average....

To go up in draw length you multiply x 1.05 each inch

I think many folks think a typical 3lbs per inch but that’s more referring to a 60lb draw weight as a baseline from history.... It just doesn’t work that way across the spectrum of weights.

Hope this helps

[ron w]

I just go by 2-2.5 pounds per inch........most times real close. Hard to beat buying a good bow scale.