Track your fertile window and estimated ovulation date based on your last menstrual period. Helps with family planning. Health data never leaves your device — every calculation runs locally in your browser.
Content reviewed October 2026 · About Toolzum
Calculates Basal Metabolic Rate using the Mifflin-St Jeor equation with age, sex, height, and weight. Nutritionists use it for diet planning. Health data never leaves your device — every calculation runs locally in your browser.
Calculate your daily calorie needs from BMR (Mifflin-St Jeor) times activity level. Shows basal burn plus maintenance calories for fitness planning. Health data never leaves your device — every calculation runs locally in your browser.
Computes Body Mass Index from metric or imperial height and weight inputs, categorizing the result into underweight, normal, overweight, and obese, with a healthy weight range for your height. Health data never leaves your device — every calculation runs locally in your browser.
Calculate revenue growth rate by comparing current period revenue to previous period. Track your business growth over time. Numbers never leave your device — every calculation runs locally in your browser.
Computes exact age in years, months, and days from a given birth date relative to any target date. Numbers never leave your device — every calculation runs locally in your browser.
Ovulation ≈ 14 days before the next period; the fertile window is the 5 days before plus ovulation day (sperm survive up to 5 days, the egg ~24h). Example: 28-day cycle starting May 1 → ovulation ≈ May 15, fertile May 10–16, next period ≈ May 29.
Calendar estimates weaken with irregularity — a 21–35 day range shifts ovulation by ±7 days. Track 3+ cycles to find your average, and confirm with basal-body-temperature or LH strips for conception timing.
No — calendar method alone fails ~24% yearly with typical use. Ovulation shifts with stress and illness. Use barrier or hormonal contraception if avoiding pregnancy.
Yes, by adding your average cycle length to the last period start. Re-enter each cycle's actual start to keep predictions calibrated — every result uses only the dates just entered, nothing stored.
No. All tracking runs locally in your browser. No health data is transmitted or stored.