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Running · Cycling · Walking · Hiking · Treadmill — pace, calories, heart rate zones, VO₂, fat burned, and performance predictions. One tool, every metric.
Educational estimates only. This calculator provides fitness estimates for informational purposes. It is not medical advice. Actual results vary by fitness level, health condition, terrain, weather, and device accuracy. Consult a physician before starting any exercise program.
Measure first thing in the morning
1 MET is the rate of energy consumption sitting quietly: ~3.5 ml O₂/kg/min or ~1 kcal/kg/h. Running at 10 km/h ≈ 10 METs — 10× resting metabolism. The Ainsworth Compendium (2011) catalogues 821 activities with validated MET values used in research and clinical practice worldwide.
Training zones are percentages of Heart Rate Reserve (HRR = Max HR − Resting HR). Zone 2 (60–70% HRR) is the aerobic base zone — most elite athletes spend 80% of training here. Zone 4 (80–90%) builds lactate threshold. Zone 5 (90–100%) develops VO₂max and neuromuscular power.
VO₂max is the maximum oxygen uptake — the gold standard for cardiovascular fitness. Untrained adults: 30–40 ml/kg/min. Recreational athletes: 45–55. Elite marathoners: 70–85. Every 1-MET increase in exercise capacity is associated with ~13% reduction in cardiovascular mortality (Myers et al., NEJM 2002).
Your body always burns a mixture of fat and carbohydrates. At low intensity (<60% VO₂max), fat provides ~50–60% of energy — ideal for long-duration, low-intensity exercise. At high intensity (>80% VO₂max), carbohydrates dominate. The "fat-burning zone" is real but not superior for total fat loss — total calorie deficit matters most.
Pace (min/km or min/mile) is the time per unit distance: pace = 60/speed(km/h). A 10 km/h pace = 6:00/km = 9:39/mile. Converting units: 1 km = 0.621 miles; 1 mph = 1.609 km/h. Riegel's formula relates race performances: t₂ = t₁ × (d₂/d₁)^1.06 — the exponent reflects the ~6% additional fatigue cost per doubling of distance.
Cycling power (watts) is the rate of mechanical work output. It depends on speed, rolling resistance (Crr ≈ 0.005 for road tires), and aerodynamic drag (CdA ≈ 0.25–0.35 m² for a road cyclist). Power = (Crr × m × g + 0.5 × ρ × CdA × v²) × v. Functional Threshold Power (FTP) — 1-hour sustainable power — is typically 3.5–5.5 W/kg for trained cyclists.
A unified workout calculator for running, cycling, walking, hiking, treadmill, and general cardio. Enter distance, time, body weight, and a few personal details to estimate pace, calories, MET, VO₂ consumption, heart-rate zones, fat-vs-carb energy split, and equivalent race times — all in one tool.
Each activity uses a metabolic equivalent (MET) value from the 2011 Ainsworth Compendium. Calories burned are then computed as MET × body-weight (kg) × duration (hours). Heart-rate zones use the Karvonen heart-rate-reserve method, which combines age and resting heart rate for individualised target zones.
For running and cycling, the assistant also estimates VO₂ consumption using the ACSM walking and running metabolic equations. These are population-derived equations that estimate the oxygen cost of locomotion at common speeds and grades.
Race-time predictions use Peter Riegel's 1981 endurance formula: t₂ = t₁ × (d₂ / d₁)¹·⁰⁶. Riegel's exponent (1.06) assumes an evenly trained aerobic athlete; predictions become less reliable far from the input distance.
speed = distance ÷ time — Average speed during the activity.pace = time ÷ distance — Time taken per unit of distance (min/km or min/mile).kcal = MET × weight(kg) × hours — Ainsworth 2011 Compendium. 1 kcal ≈ 4.184 kJ.HRmax ≈ 220 − age (or 208 − 0.7 × age, Tanaka) — Population estimate; individuals vary by ~±10 bpm.THR = (HRmax − HRrest) × intensity% + HRrest — Heart-rate reserve method.VO₂ ≈ MET × 3.5 ml·kg⁻¹·min⁻¹ — Resting MET ≈ 3.5 ml O₂/kg/min.t₂ = t₁ × (d₂ / d₁)^1.06 — Endurance event time scaling.Inputs: Activity: running. Distance: 5 km. Time: 25 min. Weight: 70 kg. Age: 30. Sex: male.
Speed = 5 ÷ (25/60) = 12 km/hPace = 25 ÷ 5 = 5:00 min/kmRunning at 12 km/h ≈ MET 11.5 → kcal = 11.5 × 70 × (25/60) ≈ 335 kcalHRmax ≈ 220 − 30 = 190 bpmResult: 12 km/h, 5:00/km, ≈ 335 kcal (≈ 1 402 kJ), HRmax ≈ 190 bpm.
Inputs: Activity: cycling. Distance: 24 km. Time: 60 min. Weight: 80 kg. Age: 35. Sex: female.
Speed = 24 km/h, Pace = 2:30 min/kmCycling at 24 km/h ≈ MET 9.8 → kcal = 9.8 × 80 × 1 ≈ 784 kcalHRmax ≈ 220 − 35 = 185 bpmResult: 24 km/h, ≈ 784 kcal (≈ 3 280 kJ), HRmax ≈ 185 bpm.
Calorie estimates are typically within ±10–20 % of indirect-calorimetry measurements. They are excellent for goal-setting but not for clinical use.
1 MET is the energy used at rest, ≈ 3.5 ml O₂ per kg per minute, or ≈ 1 kcal per kg per hour. Walking at 5 km/h is ~3.5 METs; running at 10 km/h is ~10 METs.
Target HR = (HRmax − HRrest) × intensity% + HRrest. It uses heart-rate reserve, which adapts the zone to your resting heart rate.
Riegel's 1981 formula scales finishing time with distance: t₂ = t₁ × (d₂/d₁)^1.06. It assumes consistent aerobic fitness and even pacing.
No. The figure shown is the oxygen cost of the workout you entered, not your maximal aerobic capacity. A true VO₂max test requires lab equipment.
Yes — distance in km or miles, weight in kg or lb, height in cm or feet/inches. Outputs include both km/h and mph plus min/km and min/mile pace.
Yes. For running and walking on a treadmill, you can enter incline as a percentage and the ACSM equation will adjust the oxygen cost.
Approximate substrate use is inferred from intensity (% of HR reserve). Lower intensities use a higher proportion of fat; higher intensities use more carbohydrate.
Equations were validated mainly on healthy adults aged 18–65. Estimates for children, pregnant individuals, or athletes with chronic conditions can be inaccurate.
Inputs stay in your browser. Optional AI Insight requests are anonymised and proxied through the server with no permanent storage of personal data.
The formulas, MET tables, and references are reviewed against current ACSM guidance at least once per year.
No. The tool is educational. If you have heart, joint, or metabolic conditions, consult a qualified healthcare professional before changing your training.
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