Health & Fitness topic
Getting Fit & Nutrition calculators
Estimate your energy needs, body composition, and activity targets so training and nutrition goals are grounded in real numbers.
Reviewed by BoringToolsKit · August 24, 2026 · Planning information, not professional advice.
Getting Fit & Nutrition: the big picture
Getting fit and managing nutrition is largely a numbers game: calories consumed, calories burned, water intake, and the macro split of what you eat. You don't need an app or an account to track any of it — you need the right estimates. BoringToolsKit's health calculators turn your height, weight, age, and activity into a calorie target, a water goal, and a body-mass index you can act on, all computed locally in your browser.
- Maintenance calories = what you burn in a day; cut them to lose weight.
- Activity level is the biggest variable in any calorie estimate.
- BMI is a screening number, not a diagnosis.
- Estimate your maintenance calories from your height, weight, age, and activity.
- Set a calorie goal (a ~500-calorie daily deficit targets ~1 lb/week).
- Check your water intake and BMI against evidence-based ranges.
Worked example: the 45-year-old at 5′10″, 190 lb
- Step 1: BMI Calculator — Enter 190 lb and 70 in See: BMI 27.3 — in the overweight band
- Step 2: BMR & TDEE Calculator — Enter 45 years old, 190 lb, 5′10″, moderate activity See: Maintenance runs about 2,850 calories a day
- Step 3: Calorie Calculator — Use the 2,850 maintenance number with a 500-calorie deficit See: A ~2,350-calorie target aims at about 1 lb per week
- Step 4: Daily Hydration Calculator — Enter 190 lb See: A water goal around 95 oz a day
Numbers depend on the inputs you enter; the walkthrough shows one realistic scenario.