calculating 15 and 10 rep maxes

[amusing]

I'm coming off a 5x5 and I have my 5 rep maxes. What math can I do to figure out the 10 and 15 rep maxes?

 

[imported_electric]

The "take a week to test your maxes" math.  

One approximation is to get your 5RM and divide by 85% that should get your ~ 1RM. Then get your 1RM and multiply by 70% for your 10RM and by 60% for your 15RM. So, for example, if your 5RM for a lift is 100 then your 1RM should be around 118, your 15RM around 71 and your 10RM close to 82.
But, really, take like a week to test your maxes and you won't be sorry.

 

[navigator]

Also, you might want to lower the 15RM and 10RM weights bit. If you've been on lower reps for a while, you'll likely find the 15s to be brutal. Using a bit lower weight on the 15s won't ruin the HST cycle. You can always push up the weights later.

Just a bit of advice.

 

[Bryan Haycock]

You can us the HST RM Calculator for a good estimate of your maxes.

 

[quadancer]

I've been through a lot of the calculators and tried out my maxes and found most all of them lacking, but here's another from Joe Skopec for powerlifting that I've found to be the most accurate:
http://www.joeskopec.com/repmax.html
Use that and the HST calc and you'll have a better idea of your strengths. None of the others I've found comes close to the truth.