published Jul 15, 2020

One Rep Max Calculator

Use note: sometimes these equations will spit out answers that don't really make sense, e.g. negative reps. Checking 'sensible outputs' mitigates that as follows:

no negative reps; outputs 0 instead.
- unfortunately some of the formulas will still output ludicrous reps with submaximal weight.
when calculating reps:
- if the weight is more than your 1RM, output 0 reps.
- if the weight is your 1RM, output 1 rep.
when calculating 1RM: if you do one rep with a weight, output that entered weight.

sensible outputs raw outputs

What is my 1RM if I do for reps?

Average	Epley	Brzycki	McGlothin	Lombardi	Mayhew	O'Conner	Wathen
-	-	-	-	-	-	-	-

If my 1RM is how many reps can I do with ?

Average	Epley	Brzycki	McGlothin	Lombardi	Mayhew	O'Conner	Wathen
-	-	-	-	-	-	-	-

If my 1RM is what is my rep max?

Average	Epley	Brzycki	McGlothin	Lombardi	Mayhew	O'Conner	Wathen
-	-	-	-	-	-	-	-

If I do reps with weight, how many reps can I do with weight?

Average	Epley	Brzycki	McGlothin	Lombardi	Mayhew	O'Conner	Wathen
-	-	-	-	-	-	-	-

If I do weight for reps, how much weight can I do for reps?

Average	Epley	Brzycki	McGlothin	Lombardi	Mayhew	O'Conner	Wathen
-	-	-	-	-	-	-	-

Equations

	Solve for 1RM	Solve for reps	Solve for >1 RM
Epley	$m = w (1 + \frac{r}{30})$	$r = 30 (\frac{m}{w} - 1)$	$w = \frac{m}{1 + \frac{r}{30}}$
Brzycki	$m = w (\frac{36}{37 - r})$	$r = 37 - \frac{36 w}{m}$	$w = m (\frac{37 - r}{36})$
McGlothin	$m = \frac{100 w}{101.3 - 2.67123 r}$	$r = \frac{101.3 - \frac{100 w}{m}}{2.67123}$	$w = m (\frac{101.3 - 2.67123 r}{100})$
Lombardi	$m = w r^{0.10}$	$r = \sqrt[0.10]{\frac{m}{w}}$	$w = \frac{m}{r^{0.10}}$
Mayhew	$m = \frac{100 w}{52.2 + 41.9 e^{- 0.055 r}}$	$r = \ln (\frac{\frac{100 w}{m} - 52.2}{41.9}) \div - 0.055$	$w = \frac{m (52.2 + 41.9 e^{- 0.055 r})}{100}$
O'Conner	$m = w (1 + \frac{r}{40})$	$r = 40 (\frac{m}{w} - 1)$	$w = \frac{m}{1 + \frac{r}{40}}$
Wathen	$m = \frac{100 w}{48.8 + 53.8 e^{- 0.075 r}}$	$r = \ln (\frac{\frac{100 w}{m} - 48.8}{53.8}) \div - 0.075$	$w = \frac{m (48.8 + 53.8 e^{- 0.075 r})}{100}$