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Health estimates that show their work.

Calculate calories, body measurements, and pregnancy dates—then inspect the formula, assumptions, worked examples, limitations, and repeatable test cases behind the result.

Start with calories Build a pregnancy timeline

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Calculators

Choose the number you want to understand

Each tool stays focused on one question and keeps results hidden until valid information is entered.

Calories & macros

Calorie calculator

Get a practical starting estimate for calories and macros—plus the context needed to adjust it without treating a formula like a prescription.

Use calculator BMI

BMI calculator

Calculate body mass index in U.S. or metric units, then interpret the number as a broad screening measure—not a diagnosis.

Use calculator Energy

BMR calculator

Estimate the calories your body may use at rest before walking, working, training, and digestion are added.

Use calculator Body composition

Body-fat calculator

Use a Navy-style circumference formula for a repeatable estimate that is most useful for tracking a trend.

Use calculator Body composition

Waist-to-height calculator

Compare waist circumference with height to add body-fat distribution context beyond body weight alone.

Use calculator Pregnancy dating

Due-date timeline

Turn one known date into a transparent pregnancy timeline while keeping an online estimate separate from an official clinical due date.

Use calculator

How it works

Every result has an audit trail

Calculate locally

Enter U.S. or metric units. The browser validates the values and performs the arithmetic without sending calculator inputs to us.

Inspect the method

See the exact formula, an independent worked example, the assumptions, and the cases where the estimate is a poor fit.

Reproduce the test

Each tool publishes reference inputs and expected outputs so a visitor can verify the implementation instead of taking it on trust.

Featured guides

Go beyond the output

These guides answer the questions most calculators leave unresolved.

Calories & macros

How Many Calories Should I Eat? Build and Test an Estimate

Build a calorie estimate from BMR and activity, see a worked example, choose a goal adjustment, understand macros, and test the result against a real trend.

Read guide Calories & macros

How to Choose an Activity Level for a Calorie Calculator

Use a seven-day audit of work, steps, training, and recovery to choose an activity factor and test adjacent estimates without overstating exercise.

Read guide Body composition

Body-Fat Percentage Estimates: Methods, Measurements, and Error

Understand what body-fat percentage means, where to place a tape, how circumference equations work, and why methods can disagree.

Read guide Body composition

Waist-to-Height Ratio: Formula, Measurement, and Context

Calculate waist-to-height ratio, follow a repeatable waist protocol, interpret the 0.5 screening boundary, and compare it with BMI and body-fat estimates.

Read guide Pregnancy dating

How Pregnancy Due Dates Are Calculated: LMP, Conception, IVF, and Trimesters

Compare LMP, conception, and IVF due-date arithmetic; understand irregular cycles, trimester boundaries, worked examples, ultrasound dating, and limitations.

Read guide BMI

BMI Categories and Limitations: What the Number Misses

Understand adult BMI categories, calculate a worked example, and see why BMI cannot distinguish muscle, fat distribution, fitness, or individual health.

Read guide

Scope and responsibility

A narrower library, maintained more carefully

WellnessCalcs deliberately focuses on six calculations that can be explained, tested, and bounded. The tools provide educational estimates; they cannot review symptoms, medication, medical history, laboratory results, pregnancy health, or individual nutrition needs.

Use professional guidance for pregnancy care, children, eating-disorder history, chronic disease, unexplained weight change, or any result that conflicts with medical advice.

See the publishing and testing process