Free tools
Seven calculators for the gym, working right here in your browser. Each one shows the formula it uses, and nothing you type leaves this page.
These are estimates from published formulas, not a diagnosis. For decisions about your health, talk to a doctor or a registered professional.
Enter a load and how many clean reps you did with it. The estimate is most reliable up to 10 reps.
Epley: 1RM = load × (1 + reps ÷ 30). Brzycki: 1RM = load × 36 ÷ (37 − reps). Lombardi: 1RM = load × reps^0.10. With a single rep, the load itself is the 1RM.
Enter the total weight you want on the bar and see which plates go on each side.
Each side = (total − bar) ÷ 2, filled with the heaviest plates first. Metric plates: 25, 20, 15, 10, 5, 2.5 and 1.25 kg. Imperial plates: 45, 35, 25, 10, 5 and 2.5 lb.
Enter your working weight to get a ramp of lighter sets that leads up to it.
Empty bar for 10 reps, then 40% for 8, 60% for 5, 80% for 3 and 90% for 1, rounded to 2.5 kg or 5 lb. Sets lighter than the bar are skipped.
A quick ratio between weight and height. It cannot tell muscle from fat, so people who lift often read high.
BMI = weight in kg ÷ (height in m)². Adult ranges used by the World Health Organization: under 18.5, 18.5 to 24.9, 25 to 29.9, and 30 or more.
Estimate how much energy you use in a day and split a daily target into protein, fat and carbs.
Resting energy by Mifflin-St Jeor: 10 × weight in kg + 6.25 × height in cm − 5 × age, plus 5 for men or minus 161 for women. Daily expenditure = resting × activity factor (1.2 to 1.9). Target: 15% less to lose fat, 10% more to gain. Protein 1.8 g per kg, fat 25% of the calories, carbs the rest.
Estimate body fat with a tape measure, using the US Navy method. Measure relaxed, at the same time of day.
US Navy method, measures in cm. Men: 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. Women: 495 ÷ (1.29579 − 0.35004 × log10(waist + hips − neck) + 0.221 × log10(height)) − 450.
Find your five training zones from your age. Add your resting heart rate for zones that fit you better.
Max heart rate by Tanaka: 208 − 0.7 × age (the older 220 − age is shown for comparison). Zones start at 50, 60, 70, 80 and 90% of the max. With a resting heart rate, the Karvonen method is used: rest + % × (max − rest).
Free tools
No. They are estimates from formulas published in sports science and widely used by coaches. People differ, so take them as a starting point and talk to a doctor or a registered professional about decisions on your health.
No. The numbers are worked out in your browser and are never sent to Gym+ or to anyone else.
None is exact. Epley and Brzycki agree closely up to about 10 reps, and above that every formula drifts. That is why the result shows the three side by side.
Yes. The Gym+ app has calculators for 1RM, plates, warm up, BMI, calories and body fat, right next to your workouts.
Gym+ app
Log every set, follow your progress and keep the calculators next to your workouts. 7 days free.
Gym+ is coming to the App Store soon. On Android it is already on Google Play.
