Free Fitness Calculators
Sixteen free calculators and tools, no signup required. Enter your numbers once in the Complete Analysis calculator and get BMR, TDEE, BMI, macros, body fat, heart rate zones and your calorie target together — or use any single calculator on its own. Every result can be shared, emailed to you, or downloaded as a printable file.
The calculators
- Complete Analysis — Enter your info once — get BMR, TDEE, BMI, macros, body fat, heart rate zones and calorie target.
- Calorie Deficit — How many calories to eat to lose weight, based on your TDEE and goal.
- Muscular Potential — Casey Butt frame model: height, wrist, ankle, weight and body fat vs your natural lean-mass ceiling.
- Protein Calculator — How much protein per day for muscle gain, fat loss or maintenance, with a per-meal breakdown.
- BMI Calculator — Body Mass Index with a visual scale and healthy-range check.
- Heart Rate Zones — Five training zones for fat burn, endurance and max effort (Karvonen method).
- Running Pace — Convert time and distance to pace (min/km, min/mile) and speed (km/h).
- Calorie Burn — Calories burned by activity: walking, running, cycling, swimming, HIIT and more.
- BMR Tracker — Basal Metabolic Rate — the energy you burn at rest (Mifflin-St Jeor).
- TDEE Engine — Total Daily Energy Expenditure from your real activity level.
- Body Fat Scan — Tape-measure (US Navy) and visual body fat estimation protocols.
- Lean Mass — Fat-free mass, to judge performance ratios honestly.
- Ideal Weight — Your physiological sweet-spot weight range.
- Macro Planner — Split calories into protein, fat and carbohydrates for your goal.
- Hydration Matrix — Daily water intake against body weight, sweat rate and environment.
- 1RM Estimator — Predict your one-rep max from a sub-maximal set (Epley), with training percentages.
How to use them
- Input biometrics. Current weight, height, age and biological markers.
- Define activity. Pick the activity coefficient that reflects your real physical load.
- Get the numbers. The engine processes your variables against published physiological formulas.
- Apply the data. Move the output into your workout and nutrition plan.
Frequently asked questions
How many calories should I eat to lose weight?
To lose weight safely, eat 500 calories below your TDEE (Total Daily Energy Expenditure). Use our Calorie Deficit Calculator to find exactly how many calories you need. A 500 calorie daily deficit equals about 0.5 kg (1 pound) of weight loss per week. For example, if your TDEE is 2000 calories, eat 1500 calories daily.
How much protein do I need per day?
It depends on your goal. For muscle gain: 1.6-2.2g per kg body weight. For weight loss (preserving muscle): 1.6-2.4g per kg. For general health: 1.2-1.6g per kg. A 70kg person building muscle needs about 130g protein daily, spread across 4 meals (32g each). Use our Protein Calculator for your exact number.
What is a healthy BMI?
A healthy BMI is between 18.5 and 24.9. Under 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese. However, BMI does not account for muscle mass — muscular athletes may have a high BMI but low body fat. Use our BMI Calculator alongside the Body Fat Calculator for a more complete picture.
What are heart rate zones and why do they matter?
Heart rate zones are ranges based on your max heart rate. Zone 1 (50-60%) is recovery, Zone 2 (60-70%) is fat burning, Zone 3 (70-80%) is aerobic endurance, Zone 4 (80-90%) is anaerobic threshold, and Zone 5 (90-100%) is max effort. Training in Zone 2 maximizes fat burning, while Zone 4-5 improves speed and VO2 max.
How do I calculate my running pace?
Divide your total time by the distance covered. For example, if you ran 5km in 25 minutes, your pace is 5:00 min/km. Our Pace Calculator converts between min/km, min/mile, and km/h automatically. A good beginner pace is 6:00-7:00 min/km, intermediate is 5:00-6:00, and advanced is under 4:30.
How many calories does walking burn?
Walking burns approximately 3.5 METs, which means a 70kg person burns about 250 calories per hour of brisk walking. Running burns nearly 3x more (700+ cal/hr). Our Calorie Burn Calculator computes exact numbers based on your weight, activity type, and duration across 10 different exercises.
What is BMR and why does it matter?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest - just to keep you alive (breathing, circulation, cell production). It's the foundation for calculating your daily calorie needs. Our BMR calculator uses the Mifflin-St Jeor equation, considered the most accurate formula.
What is TDEE and how is it different from BMR?
TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor. While BMR is calories burned at rest, TDEE includes all daily activities - exercise, walking, even digesting food. TDEE is what you actually burn in a day and should be used for diet planning.
How do I calculate body fat percentage without calipers?
Our body fat calculator uses the US Navy method, which only requires a tape measure. For men: measure neck and waist circumference. For women: measure neck, waist, and hip circumference. It is a tape-measure estimate: studies put it within roughly 3-4 percentage points of lab methods for most people, so use it to follow a trend rather than as an exact figure.
How accurate is the one rep max calculator?
Our 1RM calculator uses the Epley formula, accurate within 5-10% for most lifters when using 2-10 rep sets. It's most accurate with 3-6 reps. The calculator also shows training percentages (95%, 90%, 85%, 80%) commonly used in strength programs.
Deeper guides: Calorie deficit guide · How much protein per day · Muscular potential calculator (Casey Butt)
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