Health & Fitness Calculators
23 free in-browser health calculators — ideal weight, body fat percentage, heart rate zones, daily water intake, macro nutrients, and pregnancy due date. No signup, instant results.
Ideal Weight Calculator
Calculate ideal body weight using four medical formulas: Devine, Robinson, Miller, and Hamwi.
Body Fat Calculator
Estimate body fat percentage using the US Navy method based on waist, neck, and height measurements.
Heart Rate Zones
Calculate your 5 training heart rate zones based on your maximum heart rate or age.
Water Intake Calculator
Calculate your recommended daily water intake based on weight, activity level, and climate.
Macros Calculator
Calculate your daily protein, carbohydrate, and fat targets based on your TDEE and fitness goal.
Pregnancy Due Date Calculator
Calculate your estimated due date from your last menstrual period or conception date.
Calorie Burn Calculator
Estimate calories burned during 40+ types of exercise using MET (Metabolic Equivalent of Task) values.
One Rep Max Calculator
Estimate your one-rep max (1RM) for any lift using Epley, Brzycki, and other validated formulas.
Running Pace Calculator
Calculate your running pace, speed, or finish time for any distance. Convert between min/km and min/mile.
Sleep Calculator
Find the best times to wake up or go to sleep based on 90-minute sleep cycles. Avoid waking mid-cycle.
Protein Intake Calculator
Calculate your optimal daily protein intake based on body weight, activity level, and fitness goal.
VO2 Max Calculator
Estimate your VO2 max from a Cooper 12-minute run, Rockport walk test, or resting heart rate method.
Waist-to-Hip Ratio Calculator
Calculate your waist-to-hip ratio and cardiovascular health risk using WHO classification guidelines.
Lean Body Mass Calculator
Calculate your lean body mass using Boer, James, and Hume formulas. Shows fat mass and body fat percentage.
Caloric Deficit Calculator
Find out how long it will take to reach your target weight based on a daily caloric deficit.
Pregnancy Weight Gain Calculator
Calculate recommended pregnancy weight gain based on pre-pregnancy BMI using IOM 2009 guidelines.
Menstrual Cycle Calculator
Predict your next period, ovulation date, and fertile window based on your average cycle length.
Sleep Debt Calculator
Track how much sleep debt you've accumulated over the week by logging your actual vs target sleep hours each day.
Keto Macro Calculator
Calculate your ketogenic diet macros — calories, net carbs, protein, and fat — based on your TDEE and the standard keto split.
Alcohol Unit Calculator
Calculate alcohol units in any drink by volume and ABV. Track your weekly total and see how it compares to low-risk guidelines.
1-Mile Run Fitness Test
Estimate your VO2 max from your 1-mile run time using the George et al. (1993) validated formula. Shows fitness category by age and gender.
Fiber Intake Calculator
Calculate your recommended daily fiber intake by age and gender. Shows how to meet your target with common high-fiber foods.
Caffeine Calculator
Calculate your safe daily caffeine limit by body weight and find what time you should stop drinking coffee to sleep by a target bedtime.
About these health tools
Every calculator runs entirely in your browser — no account, no data sent to a server. All tools use established medical and sports science formulas. Results are estimates based on population averages; always consult a healthcare professional before making significant changes to your diet or training.
What is the Navy body fat method?
The US Navy circumference method estimates body fat percentage from neck circumference, waist circumference (and hip for women), and height. It is widely used because it requires only a tape measure and is reasonably accurate (±3–4%) for most people without extreme muscle mass.
What are heart rate training zones?
Heart rate zones divide your training intensity into five bands based on a percentage of your maximum heart rate. Zone 1 (50–60% max HR) is light recovery; Zone 2 (60–70%) is fat-burning aerobic; Zone 3 (70–80%) is aerobic fitness; Zone 4 (80–90%) is lactate threshold; Zone 5 (90–100%) is maximum effort. Most endurance training plans emphasize spending 80% of time in Zones 1–2.
What are macros and why do they matter?
Macronutrients (macros) are the three main categories of food energy: protein (4 cal/g), carbohydrates (4 cal/g), and fat (9 cal/g). Your macro targets depend on your total daily energy expenditure (TDEE) and goal — building muscle requires higher protein; fat loss requires a calorie deficit. The macros calculator derives targets from your TDEE automatically.