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.
- Running
How to Convert Running Pace Between min/mile and min/km
A mile is exactly 1.609344 km, so converting a pace is one division. The seconds are where it goes wrong. 8:30 per mile is worked through to 5:17 per kilometre, with a two-way reference table and the shortcuts that cost over a minute across a marathon.
- Running
The Riegel Formula: Predicting Race Times
The Riegel formula scales a known race time to any other distance using one fitted exponent of 1.06. Here is where that number came from, how to work the arithmetic by hand, and the distances at which the estimate starts to drift.
- Running
How to Predict Marathon Time
A half marathon in 1:45:00 does not double into a 3:30:00 marathon. This guide works through how to predict marathon time with the Riegel formula, step by step, and shows where the estimate runs faster than the day itself.
- Running
What Is VDOT? The Jack Daniels Formula Explained
VDOT turns one race result into a single running fitness score on the VO2max scale. This guide sets out both Daniels-Gilbert equations in full, works a 45:00 ten kilometre through to 45.3 step by step, and marks the durations where the model quietly stops meaning what it says.
- Running
How to Calculate Running Pace (min/km and min/mile)
Running pace is time divided by distance, but the seconds conversion and the exact mile factor are where hand calculations go wrong. A 10 km run in 52:30 is worked through to 5:15 min/km, 8:27 min/mile and 11.43 km/h, with each figure cross-checked by a second route.
- Energy Expenditure
What Is a MET? Metabolic Equivalents and Calorie Burn
A MET expresses activity intensity as a multiple of resting energy use. This guide covers the definition, both conversion routes to kilocalories, a fully worked example landing at 172 kcal, and the three separate reasons two honest calculators disagree on the identical session.
- Energy Expenditure
How Many Calories Does Rowing Burn? The MET Answer
Rowing calorie estimates rest on a MET value, body mass and duration. This guide works the formula through step by step, shows why a Concept2 monitor reads about 110 kcal higher on the same 30 minutes, and sets out where the estimate holds and where it drifts.
- Energy Expenditure
How Many Calories Does Lifting Weights Burn? The MET Answer
Weight training calorie burn comes from a MET value, body mass and working time. This guide works the formula through step by step, separates the gross figure from the net, explains why two well-sourced calculators can differ by 5%, and shows what the afterburn is actually worth.
- Energy Expenditure
How Many Calories Does Swimming Burn? The MET Answer
Swimming calorie burn comes from a MET value, body mass and duration. This guide works the formula through step by step, corrects the widespread mistake of rating breaststroke below freestyle, and shows where the estimate stops describing water.
- Energy Expenditure
How Many Calories Does Cycling Burn? The MET Answer
Cycling calorie burn is estimated from body mass, a MET value and duration rather than measured directly. This post sets out the equation, works one 45 minute ride through in full, and shows why gross, net and the two rival MET definitions rarely agree.