Free Fitness Calculators: BMI, TDEE, Protein & Body Fat

Calculate Your Numbers

Pick a calculator below and get your results instantly.

These calculators give estimates for general fitness and information only. Results may not suit everyone and are not medical or professional advice. If you have a medical condition, are pregnant, have specific dietary needs, or are unsure whether a target is right for you, speak to a qualified healthcare professional.

BMI Calculator

Enter your weight and height to calculate your Body Mass Index.

Weight (kg)

Height (cm)

–

Body Mass Index

UnderweightBelow 18.5

Healthy weight18.5 – 24.9

Overweight25 – 29.9

Obese30 and above

BMI is a screening measure, not a diagnosis of health or body composition. It doesn't account for muscle mass; athletes often have a higher BMI despite being very lean.

1 Rep Max Calculator

Estimate your one rep max using the Epley formula, without risking a max effort lift.

Weight lifted

Unit

Reps completed

–

Estimated 1 Rep Max

Estimated 1RM–

90% Training Max–

85% Working Weight–

80% Working Weight–

Uses the Epley formula: 1RM = weight × (1 + reps ÷ 30). Best for 1–10 rep ranges.

Macro Calculator

Calculate your daily calorie and macro targets based on your goal and activity level.

Weight (kg)

Goal

Activity level

–

Daily Calories

Protein–

Carbohydrates–

Fat–

Based on estimated BMR using body weight. For personalised targets based on your height, age and full stats, use the Macro Calculator inside the REVIVE app.

Daily Calorie Calculator (TDEE)

Work out how many calories you burn a day, and your target to lose, maintain or build muscle.

Gender

Age

Weight (kg)

Height (cm)

Activity level

Goal

–

Your daily calorie target

Maintenance–

Your target–

Estimated with the Mifflin-St Jeor formula. Track your intake and adjust after 2–3 weeks inside the REVIVE app.

Protein Calculator

Estimate your daily protein target to build muscle, lose fat or maintain.

Weight (kg)

Goal

–

Daily protein target

Per day–

Per meal (4 meals)–

Adequate protein can help support muscle retention during fat loss and muscle growth, alongside resistance training. Spreading it across the day is a common approach.

Body Fat Calculator

Estimate your body fat using the US Navy tape method. Measure in centimetres.

Gender

Height (cm)

Neck (cm)

Waist (cm)

Hips (cm), women only

–

Estimated body fat

The US Navy method provides an estimate and can differ from more precise measurements such as a DEXA scan. Measure at the same time of day.

Water Intake Calculator

Estimate how much water to drink each day based on your weight and activity.

Weight (kg)

Activity level

–

Daily water target

Litres per day–

Glasses (250ml)–

Individual fluid needs vary. Drink more on hot days or during intense training, and follow medical advice if you have a condition affecting fluid intake. Track it in the REVIVE app.

All These Calculators Are Built Into REVIVE

These calculators are built into the REVIVE app on iPhone (Starter plan and above), alongside workouts, meal plans, AI coaching and progress tracking. Want them free? Get the free Fit Calculator app below.

Prefer These On Your Phone?

Get Fit Calculator, free to download.

The same calculators above, plus 1 Rep Max, as a free app for iPhone. No account needed.

Download free →

Learn more about Fit Calculator →