Health calculators that explain what the number means
Most calculators hand you a figure and leave you to Google what it means. CalcMyHealth pairs every result with a plain-language readout — where you fall, why it matters, and what a reasonable next step looks like — using the same formulas clinicians and dietitians reference.
BMI calculator
Body Mass Index estimates whether your weight falls in a typical range for your height.
What BMI does and doesn't tell you
BMI divides weight by the square of height. It's a fast population-level screen, not a diagnosis — it was designed for tracking trends across large groups, not judging one individual body.
- It can't tell muscle from fat, so athletes and very muscular people often read "overweight" despite low body fat.
- It doesn't account for age, sex, bone density, or where fat is carried on the body.
- Waist circumference or body fat % (below) usually add more useful context.
BMI is a screening tool, not a diagnosis. Talk to a healthcare provider for a full picture of your health.
Daily calorie calculator
Estimate the calories you'd eat to maintain, lose, or gain weight at a steady pace.
How this is calculated
We estimate your basal metabolic rate with the Mifflin-St Jeor equation, then multiply by an activity factor to get total daily calorie needs. It's one of the more accurate equations available for estimating resting metabolism in non-clinical settings.
These are estimates based on population averages. A registered dietitian can tailor targets to your medical history and goals.
Body fat % calculator
Estimate body composition from tape-measure circumferences using the U.S. Navy method.
Measure waist at the navel and neck just below the larynx, tape snug but not compressed.
Accuracy of the Navy method
This method has a margin of error of roughly ±3–4 percentage points against a DEXA scan, which remains the gold standard for precise body composition. Treat the result as a useful estimate for tracking trends over time, not a lab-grade measurement.
For clinical-grade body composition analysis, ask your provider about a DEXA scan or bioelectrical impedance test.
TDEE & macro calculator
Total Daily Energy Expenditure — your full calorie burn, broken into protein, carbs, and fat.
BMR vs. TDEE — what's the difference?
BMR is the energy your body uses at complete rest just to keep organs running. TDEE adds in movement, exercise, and daily activity on top of that baseline — it's the number that actually reflects what you burn in a day.
Individual needs vary with genetics, hormones, and health conditions. A dietitian can personalize these figures.
Pregnancy due date calculator
Estimate your due date from your last period using Naegele's rule.
How Naegele's rule works
The rule adds 280 days (40 weeks) to the first day of your last period, assuming a fairly typical 28-day cycle. If your cycles run longer or shorter, the adjustment for cycle length shifts the estimate closer to your actual conception date.
This is an estimate. Your care provider's dating ultrasound is the most reliable way to confirm gestational age.
Ovulation calculator
Estimate your fertile window and likely ovulation date.
Why cycles vary
Ovulation typically occurs about 14 days before the next period starts, regardless of cycle length — so a longer cycle usually means ovulation happens later, not that the luteal phase changes much. Stress, illness, and travel can all shift the actual date.
This tool estimates averages and is not a reliable method of contraception or fertility diagnosis.
Blood pressure checker
See where a reading falls on the American Heart Association scale.
One reading isn't the full story
Blood pressure naturally shifts through the day with stress, caffeine, posture, and activity. Clinicians typically want several readings, taken at rest and on different days, before drawing conclusions — especially before any diagnosis.
This tool is informational only. A crisis-range reading (>180/>120) with symptoms like chest pain or shortness of breath needs immediate medical attention.
Sleep cycle calculator
Work backward or forward from a target time using 90-minute sleep cycles.
Why 5–6 cycles?
Most adults need 7–9 hours of sleep, which lines up with 5 to 6 complete 90-minute cycles. Fewer than 5 cycles regularly is linked with daytime grogginess; consistently needing more may be worth mentioning to a doctor.
Cycle length varies by person and by night. Use this as a starting point, not a strict formula.
Quick reference
Formulas used across these tools: the Mifflin-St Jeor equation (calories, TDEE), the U.S. Navy circumference method (body fat), Naegele's rule (due date), and the American Heart Association's blood pressure categories. Every result is an estimate — they're built to inform a conversation with a healthcare provider, not replace one.