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Bunnzy

Free tools

Free fitness calculators for running pace, heart rate zones, one rep max and daily calories. No sign-up, instant results, everything runs in your browser.

  1. Running Pace Calculator

    Free running pace calculator: work out pace, finish time or distance in km or miles, with race times and even splits for 5K, 10K, half and marathon.

  2. Heart Rate Zone Calculator

    Find your 5 heart rate training zones from your age or measured max HR. Uses the Karvonen method with resting heart rate, or simple % of max. Free.

  3. One Rep Max Calculator (1RM)

    Estimate your one rep max from any set of 1–12 reps with the Epley and Brzycki formulas, in kg or lb, plus a training percentage chart. Free, no sign-up.

  4. TDEE Calculator: Daily Calorie Needs

    Estimate your maintenance calories (TDEE) and BMR with the Mifflin-St Jeor formula, in metric or imperial, with example targets to lose or gain weight.