Free Health Calculators
Built for Real Results
BMI, calories, macros, body fat — answer the numbers that actually matter for your health. Each calculator takes under 60 seconds.
Numbers you can
actually act on
Most people underestimate calories by 30–40%. They set goals without knowing their baseline. These calculators give you the data you need before you start — not after weeks of guessing.
Whether you're starting your first diet, hitting a plateau, or building muscle — the right numbers change everything.
For weight loss
Know your deficit target before day one.
For fitness
Dial in protein and macros for muscle.
For beginners
No nutrition knowledge needed.
For tracking
A baseline to measure progress against.
Choose your calculator
Four tools, each focused on one number. Pick the one that fits where you are right now.
BMI Calculator
Find out if your weight is in a healthy range for your height.
Know your Body Mass Index in seconds — no guesswork.
Calorie Calculator
Get your personalized daily calorie target based on your goal.
Eat the right amount — whether cutting, bulking, or maintaining.
Macro Calculator
Break your calories down into protein, carbs, and fat targets.
Stop guessing macros — get a split built around your body.
Body Fat Calculator
Estimate your body fat percentage using simple measurements.
Understand your real body composition beyond the scale.
Popular health tools
BMI Calculator
Body Mass Index for adults — metric and imperial.
Daily Calorie Calculator
TDEE-based calories for fat loss, muscle gain, or maintenance.
Macro Calculator
Protein, carbs, and fat ratios matched to your goal.
Body Fat Calculator
Navy method estimate using height, waist, and neck measurements.
One number won't change your habits
A calculator gives you a number for today. But nutrition isn't a single moment — it's every meal, every day, over months.
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One-time results. No way to track if you're actually hitting them.
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No personalization over time. Your body changes — your targets should too.
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No feedback loop. You won't know what's working until it's too late.
Track every day.
Improve every week.
SlayCal takes your calculator results and turns them into a live dashboard that updates with every meal you log.
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Snap a meal — get instant calories and macros
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Track progress automatically, day by day
- tune
Goals adapt as your weight changes
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Hydration, weight, BMI — all in one place
Ready to start?
Pick a calculator below — or download SlayCal to go from numbers to actual daily tracking.
Free download · 500 AI credits included · No credit card required