The numbers, explained
Plain-English guides to the formulas behind the calculators: how each metric is worked out, a full worked example, and what the number does and does not measure. Educational, estimates only.
- Energy Expenditure
How Many Calories Does Walking Burn? The MET Answer
Walking calorie burn comes from a MET value, body mass and duration. This guide works the formula through step by step, shows why two well-sourced calculators can differ by 29% on the identical walk, and sets out where the estimate holds and where it drifts.
- Energy Expenditure
How Many Calories Does Running Burn? The MET Answer
Running calorie burn comes from a MET value, body mass and duration. This guide works the formula through step by step, shows why two well-sourced calculators can differ by 19% on the identical run, and sets out where the estimate holds and where it drifts.
- Body Composition
Harris-Benedict vs Mifflin-St Jeor: Which BMR Formula?
Two respected BMR equations return different resting energy figures from identical inputs. This post walks through both sets of coefficients, a fully worked example and how far apart the estimates typically sit.
- Body Composition
How to Calculate Lean Body Mass (Two Formulas, One Example)
Lean body mass is total weight minus stored fat. This guide walks through the subtraction method, the Boer and Hume prediction equations, and a full worked example in metric with imperial equivalents.
- Body Composition
What Is FFMI? Fat-Free Mass Index Explained
Fat-free mass index divides lean tissue, not total weight, by height squared. This guide covers the formula, the 1.80 m height correction, and a worked example in metric with imperial equivalents.
- Body Composition
How to Measure Body Fat Percentage (Navy Method + Calipers)
Body fat percentage separates fat mass from everything else. This guide explains the Navy circumference equations in both metric and imperial, works a full example step by step, and sets out where the estimate drifts.
- Body Composition
What Is BMR? The Mifflin-St Jeor Formula, Explained
Basal metabolic rate is the energy the body spends at complete rest. This post explains what BMR is, how the Mifflin-St Jeor equation estimates it from height, weight, age and sex, and how it differs from total daily energy expenditure.
- Body Composition
What Is TDEE and How to Calculate It
TDEE estimates the total energy a body uses in a day. This guide explains the two-stage calculation, works a full example in metric and imperial units, and shows exactly where the estimate stops being reliable.
- Body Composition
How to Calculate BMI (and What the Number Actually Means)
How to calculate BMI in metric and imperial units, a full worked example, and a clear-eyed look at what the number does and does not measure.