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Fitness Calculators

Fitness Calculators

Everything you need in one place — body composition, calories, macros, strength, and pace. Fill in your stats once and they flow into every calculator.

— BMI
— Maintenance Cals
— Protein Target
— Water / Day

💾 What you type into an individual calculator is saved on this device, so a reload won't lose your measurements. Nothing here reaches your Checklist — no result becomes a target.

Your Stats

Used by every calculator below. Saved on this device only.

Used for body-fat & calorie formulas.
Height

⚖️ Body Mass Index (BMI)

A quick height-to-weight ratio. It doesn't know muscle from fat, so very muscular people read high — pair it with Body Fat below.

— enter your stats

📏 Body Fat % (tape method)

The U.S. Navy circumference method — all you need is a tape measure. Measure relaxed, against bare skin.

Women only.
— measure to begin

🔥 Daily Calories (BMR & TDEE)

How many calories you burn at rest (BMR) and across your day (TDEE), via the Mifflin–St Jeor equation. Pick a goal to see your target.

— cal/day target

BMR: —  ·  Maintenance (TDEE): —

🍽️ Macros

Splits your calorie target (from the Calories card above) into grams of protein, carbs, and fat.

Protein — Carbs — Fat —

🏋️ One-Rep Max (1RM)

Estimate the most you could lift once from a set you've actually done. Most accurate at 10 reps or fewer.

— estimated 1-rep max

🏃 Running Pace

Enter a distance and time to get your pace and speed, plus projected finish times for common races at that pace.

Time
—

💧 Water Intake

A daily target based on your bodyweight, plus extra for the time you train. Hot weather and altitude raise it further.

—
How These Are Calculated
  • BMI = weight (kg) ÷ height (m)². Healthy range is 18.5–24.9.
  • Body Fat % — U.S. Navy circumference method (log-based formula using neck, waist, height, and hips for women).
  • BMR — Mifflin–St Jeor: (10 × kg) + (6.25 × cm) − (5 × age) + 5 (men) or − 161 (women). TDEE = BMR × your activity factor.
  • Macros — your calorie target split by percentage; protein & carbs are 4 cal/g, fat is 9 cal/g.
  • 1RM — the average of the Epley and Brzycki formulas; the table uses standard %-of-1RM rep targets.
  • Pace — time ÷ distance, with race projections at a constant pace.
  • Water — about half an ounce per pound of bodyweight (≈35 ml/kg), plus ~12 oz per 30 min of exercise.

Note: these are general estimates for healthy adults, not medical advice. Talk to a doctor before making big changes, especially if you have a health condition.

❤️ Heart Rate Zones ← Checklist 📖 Glossary