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10+ free, science-backed calculators for BMI, calories, macros, body fat, sleep and more — instant results, no sign-up needed.

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10 Free Fitness Calculators

No login, no paywalls — just instant, science-backed results

BMI Calculator

Most Popular

Calculate your Body Mass Index (BMI) instantly using the WHO-standard formula. Understand your weight category and get personalized health insights.

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Calorie Calculator

Essential

Calculate your Basal Metabolic Rate (BMR) and daily calorie needs using the gold-standard Mifflin-St Jeor equation.

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TDEE Calculator

Popular

Calculate your Total Daily Energy Expenditure (TDEE) — the calories your body burns each day.

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Macro Calculator

Diet

Get personalized macronutrient targets based on your body stats and goal.

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Body Fat Calculator

Body Comp

Estimate your body fat percentage using the US Navy circumference method.

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Weight Loss Calculator

Goal Setting

Estimate the time, calorie deficit, and target date for reaching your goal weight.

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Water Intake Calculator

Hydration

Calculate your daily water intake based on body weight, activity level, and climate.

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1RM Calculator

Strength

Estimate your one-rep maximum (1RM) using three industry-standard formulas.

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Sleep Calculator

Recovery

Find an ideal bedtime based on your wake-up time and natural 90-minute sleep cycles.

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Heart Rate Zones

Cardio

Calculate your personalized heart rate training zones using the Karvonen or max-HR method.

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Peer-reviewed formulas
No data stored
Mobile friendly
Instant results
100% free forever
Quick Start

Get Results in 3 Simple Steps

No complex setup. Just pick, enter, and go.

01

Choose a Calculator

Pick from 10+ science-backed tools matched to your goal — weight loss, strength, sleep, hydration, and more.

02

Enter Your Details

Input your stats in seconds. Everything calculates instantly on your device — nothing is ever stored.

03

Act on Your Results

Get results with expert interpretation and clear, actionable next steps tailored to your specific goal.

Guides

In-Depth Fitness Guides

Evidence-based articles for every fitness goal

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Body Composition

Complete BMI Guide

What Body Mass Index means, healthy ranges, and key limitations for athletes and different body types.

Nutrition

Calories & Weight Loss

Caloric deficits, sustainable fat loss strategies, and macronutrient principles explained clearly.

Metabolism

TDEE Explained

Master total daily energy expenditure for fat loss, weight maintenance, or muscle gain.

Nutrition

Macro Nutrition Guide

Master protein, carbs, and fats to optimize body composition and athletic performance.

FAQ

Frequently Asked Questions

Everything you need to know about our calculators

Are these fitness calculators accurate?+

Our calculators use industry-standard, peer-reviewed formulas — Mifflin-St Jeor for BMR, the US Navy method for body fat, and Epley for 1RM. They provide reliable estimates, but individual results vary. Consult a healthcare professional for medical advice.

Do I need to create an account?+

No. All calculators on GetFitMetrics are free and require no account or registration. Enter your measurements to get instant results.

What is the difference between BMR and TDEE?+

BMR (Basal Metabolic Rate) is the calories your body burns at rest. TDEE (Total Daily Energy Expenditure) adds your activity level to BMR to estimate your total daily calorie burn.

How often should I recalculate my macros?+

Recalculate every 4–8 weeks, when your weight changes by 5+ lbs, your activity changes, or you shift goals (such as moving from cutting to bulking).

Can I use these calculators on mobile?+

Yes. GetFitMetrics is optimized for mobile and works on smartphones and tablets.

What BMI formula do you use?+

We use the standard WHO formula: BMI = weight (kg) ÷ height² (m). For imperial units: BMI = 703 × weight (lbs) ÷ height² (inches).

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Join thousands who use GetFitMetrics daily to track progress, set data-driven goals, and make smarter decisions about their health.

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