One Rep Max Calculator

If you can't use JavaScript, here's a table you can use to calculate your one rep max. On this table you have "Reps" and "Co-Efficients".

If you know your One Rep Max, and you want to do a set that calls for a set number of reps, multiply your reps by that coefficient to determine the proper weight for the reps (I know it's confusing, the examples at the bottom will clear it up).

If you know your "x" rep max, and you want to find out what your 1 rep max should be for that exercise, devide the coefficent by the corresponding "rep #".
 

Reps	CoEfficient
1	1.00
2	.943
3	.906
4	.881
5	.856
6	.831
7	.807
8	.786
9	.765
10	.744
11	.723
12	.703
13	.688
14	.675
15	.662
16	.650
17	.638
18	.627
19	.616
20	.606

Examples:

A routine for squats calls for you to do 3 sets of 8 reps. You want to know what a good hard set of 8 reps would be, and you know your current 1 rep max on the squat is 385 lbs. 385 x .786 = 303. You should be able to do an 8 rep set at 303 +/- 5 lbs. or so.

You are working a periodization routine, and you need to find percentages of your 1 rep max to set up your weekly routines. You don't have a spotter available to help you find a 1 rep max on your bench press, but you do know you can squeeze out (barely) 5 good reps at 230 lbs. 230 divided by .856 = 268. Your 1 rep max should be about 268 lbs. +/- 5 lbs. or so.

This chart should not be taken as an absolute, and remember if you have been doing high rep sets for the past 3 months, you are not going to be able to handle the 1 rep max that the math says you should, due to lack of tendon strength and raw power neccesary to lift low rep weights. Alternately, if you have been working 2-3 rep sets for a while, higher reps sets will take a while to get used to.

There's also an online one rep max calculator at the CyberIron Bodybuilding and Weightsnet

Here's a chart you can use to estimate your one rep max for specific lifts.
 

Repetitions	Squat	Benchpress	Deadlift
1	1.0	1.0	1.0
2	1.0475	1.035	1.065
3	1.13	1.08	1.13
4	1.1575	1.115	1.147
5	1.2	1.15	1.164
6	1.242	1.18	1.181
7	1.284	1.22	1.198
8	1.326	1.255	1.232
9	1.368	1.29	1.232
10	1.41	1.325	1.24

 

Here's another formula for calculating one rep max. Take the number of reps * .033. Then add 1 to that number. Take that number and multiply the weight you used for the number of reps. Your one rep max should be within 5 pounds on either side. For example, if you do 155 for 8 reps, 8 * .033 = .264, 1 + .264 = 1.264, 1.264 * 155 = 195.92. So your one rep max in this example should be 195. It could be anywhere from 190 to 200.

Once you have calculated your one rep max, Click here to calculate your periodization progression target

Note, you cant increase weight indefinitely (otherwise we would see world records every year) so to give you a guideline, if you weight less than 200 lbs, then benchpressing your bodyweight should be your immediate goal (remember when doing pushups (your bodyweight only) you use your strong legs so theres less strength required from your arms therefore its harder to benchpress than do pushups) then the 2nd goal is to do 200 lbs (for 12 reps at least slow and controlled). For bodybuilding purposes this is enuff to give you a massive chest if you focus on "flexing it" each rep. Note bodybuilding and power lifting are totally different sports. With bodybuilding, your goal is to gain muscle and be cut...you can gain muscle even with light weights because your ultimate aim is each rep you are flexing hard and doing the motion slow and controlled whereas in powerlifting your goal is to lift as heavy as humanly possible (with drugs) and do the movement as quick as possible using explosive strength (in bodybuilding you do NOT and should not use or need to use explosive strength).