// vitamath · v1.0
Fitness math, done right.
Accurate body composition, energy expenditure, and strength calculators with formula transparency and a healthy-range chart on every result. Computes locally — your data never leaves your browser.
// the calculators
Twenty live. More on the way.
Fitness and health calculators — BMI, body fat, TDEE, one-rep max, macros, hydration, heart-rate zones, sleep, fertility, and more. All live, all formula-transparent.
- 01live
BMI
Body Mass Index — height/weight ratio with healthy range.
open - 02live
Body fat %
Navy method body composition with fat-mass and lean-mass split.
open - 03live
TDEE
Total Daily Energy Expenditure with goal-based macro split (cut, maintain, bulk).
open - 04live
One-rep max
Estimate your 1RM from any sub-max set, across seven proven formulas.
open - 05live
Macro
Split your daily calories into optimal protein, fat, and carbs by goal.
open - 06live
Pregnancy due date
Calculate your due date from last period or conception date. Naegele's rule.
open - 07live
Ovulation
Find your fertile window and estimated ovulation day from your cycle length.
open - 08live
Calorie deficit
Daily calorie deficit for fat loss with safe rate-of-loss estimate.
open - 09live
Ideal weight
Target body weight by 5 clinical formulas (Devine, Robinson, Miller, Hamwi, BMI-based).
open - 10live
Water intake
Daily hydration target adjusted for weight, activity, and climate.
open - 11live
Heart rate zones
Training zones 1–5 from max HR or Karvonen HRR method.
open - 12live
VO₂ max
Estimated aerobic capacity from resting HR or timed run test.
open - 13live
Waist-to-hip ratio
Abdominal fat risk score — WHO risk classification included.
open - 14live
Protein intake
Daily protein target by bodyweight, goal, and activity level.
open - 15live
Sleep
Optimal wake or bedtime aligned to 90-minute sleep cycle boundaries.
open - 16live
Blood pressure guide
AHA stage classification and pulse pressure from systolic/diastolic readings.
open - 17live
Menstrual cycle
Next period and cycle phase calendar from last period and cycle length.
open - 18live
Fertility window
Peak fertile days and ovulation window across the next 3 cycles.
open - 19live
Intermittent fasting
Eating window and fast start/end times for 16:8, 18:6, and 5:2.
open - 20live
Biological age
Estimated biological age from lifestyle factors and vital signs.
open
// how we build
Principles
- 01
Formulas you can audit.
Every calculator names the formula it uses, links to the source paper, and shows you the math. No black boxes.
- 02
Pickers, not opinions.
When researchers disagree (TDEE has three good formulas, 1RM has seven), we let you choose — with the trade-offs in plain English.
- 03
Your data stays in your browser.
All calculations run locally. Nothing about your body composition is sent to a server.
- 04
Not medical advice.
These are tools for self-assessment. For diagnoses, training programmes, and clinical decisions, talk to a qualified professional.
Spotted a bug, formula issue, or missing calculator? Email us →