Fitness Calculators
Calorie Burn Calculator
Estimate calories burned across eighteen common activities using MET values combined with body weight and session duration for an accurate kcal figure.
Cycling FTP Calculator
Estimate cycling Functional Threshold Power from a 20-minute or ramp test, with a full seven-zone power training breakdown.
Exercise Calorie Estimator
Estimate calories burned using sex-specific heart-rate-based regression formulas from average heart rate, weight, age, and duration.
FTP Power Zones Calculator
Calculate the 7 standard cycling power training zones from your Functional Threshold Power (FTP) using the Coggan zone system.
Half Marathon Pace Calculator
Calculate half marathon pace or finish time from the official 21.0975 km distance, with checkpoint splits at 5K, 10K, 15K, and 20K.
Heart Rate Recovery Calculator
Calculate your 1-minute heart rate recovery after intense exercise, a recognized indicator of cardiovascular fitness.
Heart Rate Zone Calculator
Calculate five training heart rate zones using the Karvonen method or percentage of max heart rate, from age and resting heart rate.
Hiking Time Calculator
Estimate total hiking time using Naismith's Rule, factoring trail distance, elevation gain, elevation loss, and walking pace.
Karvonen Target Heart Rate Calculator
Calculate a personalized target heart rate using the Karvonen method, which accounts for resting heart rate and fitness level.
Marathon Pace Calculator
Calculate marathon pace or finish time from the official 42.195 km distance, with checkpoint splits at 5K, 10K, half, and beyond.
MET Calorie Calculator
Calculate calories burned during an activity using its standardized MET (Metabolic Equivalent of Task) value, body weight, and duration.
Navy Body Fat Calculator
Estimate body fat percentage using the US Navy circumference method from waist, neck, height, and (for women) hip measurements.
One Rep Max Calculator
Estimate your one-rep max using the Epley, Brzycki, or Lombardi formula from a submaximal set, plus a full rep-range percentage chart.
Pace Calculator
Solve for pace, time, or distance from any two running variables, with results shown in hours, minutes, and seconds for any race distance.
Riegel Race Time Predictor
Predict your race time at a new distance from a known race result using Riegel's classic exponential prediction formula.
Steps to Calories Calculator
Estimate calories burned from a step count using stride length and body weight to first calculate distance walked.
Swim Calories Calculator
Estimate calories burned swimming using stroke-specific MET values across freestyle, backstroke, breaststroke, butterfly, and more.
Training Volume Calculator
Calculate total training volume (sets times reps times weight) for tracking progressive overload in strength training.
VO2 Max Calculator
Estimate VO2 max using the Cooper 12-minute run test or a resting heart rate ratio method, with results mapped to a fitness category.
Wilks Score Calculator
Calculate your Wilks score from bodyweight and total lifted using the 1994 Wilks coefficient formula, letting lifters of any size be fairly compared.
Training With Numbers Instead of Guesswork
Effective training depends on working at the right intensity, not just working hard — heart rate zones, pace targets, and calorie estimates all help translate "how it feels" into something you can actually plan around. These eleven calculators cover the core fitness and endurance math.
Heart Rate Training Zones
Most endurance training plans deliberately spend the majority of weekly volume in the lower zones (1-2), with only a small fraction in zones 4-5 — a ratio that surprises many new runners who assume harder is always better. Find your own zones with the Heart Rate Zone Calculator.
Popular Fitness Calculators
- VO2 Max Calculator — estimates maximum oxygen consumption capacity, a standard measure of aerobic fitness.
- Marathon Pace Calculator — projects required per-mile pace to hit a target marathon finish time.
- One Rep Max Calculator — estimates maximum single-rep lift weight from a higher-rep set.
Related: Health Calculators, Nutrition Calculators for fueling training.