Health score calculator

How is it calculated?

The score starts from a base of 85, not 100. The reason is discriminating power: with a base of 100 the activity bonus would hit the ceiling for healthy users and very different bodies would all land on the same 100. Starting at 85 means reaching 100 requires all three items to be in order.

The body mass index item: below 18.5 costs 15 points, 18.5–25 costs nothing, 25–30 costs 20, above 30 costs 35. The sample body's BMI is 25.9. That item reads −20. The healthy range neither penalises nor rewards — a healthy weight is what earns you the base, not a bonus on top of it.

The body fat item works on DISTANCE from the ideal: 15% for men, 25% for women, with every percentage point of deviation costing 1.5 points. Direction does not matter; a body fat well below the ideal costs as much as one well above, because dropping under essential fat is a health problem of its own.

The activity item is stepped: sedentary costs 10 points, light activity 1–3 days a week gives 5, moderate 3–5 days gives 10, and the top two levels both give 15. THE TOP TWO LEVELS SCORE THE SAME — the last two rows of the table being equal is not a bug. Assuming no extra health gain beyond five days a week is a deliberate choice in the engine.

If you have not had your body fat measured, it is estimated from height, weight and age (Deurenberg 1991). Because that estimate takes body mass index as an input, the BMI item and the fat item are NOT INDEPENDENT: change your weight and both move together. That is why the counterfactuals below are produced by recalculating the score for the target body rather than by adding items up.

The target weight in the counterfactuals is the MIDDLE of the healthy range. Aiming at the lower end would mean aiming at a BMI of 18.5 — just above the underweight line — and anyone who got there would meet a 15-point penalty on the next step down.

How to read your result

Read the breakdown first, the score second. The story behind 59 is not "average": this body loses almost all of its points in two items, and both trace back to the same thing, excess fat tissue. The activity item is positive. Movement is already working; the problem is not there. Another body arriving at the same 59 through inactivity would need to do something completely different.

The counterfactuals are arithmetic, not a promise. "87 at a healthy weight" comes from working out what BMI and estimated body fat would be at that weight and scoring the body again. It says nothing about how long that takes; the weight loss calendar tool covers that, with the weekly rate and the date.

The biggest lever is usually weight, but the EASIEST lever is usually activity. In the sample body, losing 13.2 kg is worth 28 points and moving up one activity level is worth 5 — yet the second is something you can start this week, and it is also the engine of the first. Ordering the work by feasibility rather than by points tends to raise the score faster.

The score is UNFAIR to muscular bodies. We would rather say so plainly. Neither BMI nor estimated body fat can tell muscle from fat; both penalise in the same direction, so a trained person loses on two items at once. If you have had your body fat measured, switching the source to "measured" corrects half of that distortion; for the rest, see the lean body mass (FFMI) tool.

This score is not a health screening. Blood pressure, blood sugar, cholesterol, smoking, sleep, alcohol, stress and family history — the items that carry the weight in real risk assessments — are absent here. Scoring 90 does not prove you are healthy, and scoring 45 does not mean you are ill. The number gives a sense of direction; diagnosis is a doctor's job.