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CalcIntel

💪 46 Calculators · 13 Topics · Updated April 2026

Fitness Calculators

Free fitness calculators for strength training, running, cycling, and exercise planning. Estimate one-rep max, running pace, heart rate zones, and calories burned.

Train smarter with data. These fitness calculators help you estimate your one-rep max for strength programming, dial in your running pace for race goals, find your target heart rate zones, and track calories burned across different activities. Based on established exercise science formulas like the Epley equation for 1RM.

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Frequently Asked Questions

How is one-rep max calculated?

We use the Epley formula: 1RM = Weight × (1 + Reps/30). It's most accurate for sets of 3-10 reps. For example, if you bench 185 lbs for 5 reps, your estimated 1RM is 185 × (1 + 5/30) = 216 lbs. Use this for programming training percentages, not for attempting actual maxes without a spotter.

What heart rate zone should I train in?

It depends on your goal. Zone 2 (60-70% of max HR) is best for building aerobic base and burning fat. Zone 3-4 (70-90%) improves race performance. Zone 5 (90-100%) is for short, intense intervals. Most recreational athletes should spend 80% of training time in Zone 2.

How many calories does walking burn?

Roughly your body weight (in kg) multiplied by distance (in km). A 160-lb (73 kg) person walking 3 miles (4.8 km) burns approximately 350 calories. Speed matters less than distance, faster walking burns only slightly more per mile than slower walking.