Does Fat Mass upload my file or text to Tool-You servers?

No. Fat Mass runs in this browser tab. Files stay on the device. Limit note: Fat% in (0,100).

Should I use Lean Body Mass instead of Fat Mass?

Use Fat Mass when you need Fat mass with lean kg. Use Lean Body Mass when you need Boer estimate from mass, height, and sex. They share a category (Health) but not the same job.

Fat Mass

Fat mass with lean kg.

Body weight × body-fat % → fat mass and lean mass. Shows fat kg, lean kg, and the same fat % you entered for a quick check.

What Fat Mass does

Body weight × body-fat % → fat mass and lean mass. Shows fat kg, lean kg, and the same fat % you entered for a quick check.

Practical limit for Fat Mass: Fat% in (0,100). That is why output can differ from heavy desktop Health software. Read the tool-specific note again: Body weight × body-fat % → fat mass and lean mass. Shows fat kg, lean kg, and the same fat % you entered for a quick check.

How to use Fat Mass

Confirm you need Fat Mass, not Lean Body Mass (Boer estimate from mass, height, and sex.). Address: /health/fat-mass.
Enter the numbers or dates Fat Mass uses. Fat mass with lean kg.
Read the result as Fat Mass defines it — not as BMI Calculator (Body mass index in metric or imperial units.). Body weight × body-fat % → fat mass and lean mass. Shows fat kg, lean kg, and the same fat % you entered for a quick check.
Fat Mass is an estimate in the browser, not professional advice. Fat% in (0,100).
Need a different formula? Try BMI Calculator (Body mass index in metric or imperial units.) instead of stretching Fat Mass.

When not to use Fat Mass

Skip Fat Mass when a neighbor tool matches better — start with Lean Body Mass or BMI Calculator — or when the description already warns the job will fail. In the tool’s own words: Body weight × body-fat % → fat mass and lean mass. Shows fat kg, lean kg, and the same fat % you entered for a quick check.

Questions about Fat Mass

What does Fat Mass do that other Health pages on this site do not?: Body weight × body-fat % → fat mass and lean mass. Shows fat kg, lean kg, and the same fat % you entered for a quick check. Short version: Fat mass with lean kg.
Does Fat Mass upload my file or text to Tool-You servers?: No. Fat Mass runs in this browser tab. Files stay on the device. Limit note: Fat% in (0,100).
Should I use Lean Body Mass instead of Fat Mass?: Use Fat Mass when you need Fat mass with lean kg. Use Lean Body Mass when you need Boer estimate from mass, height, and sex. They share a category (Health) but not the same job.
What are the limits of Fat Mass?: Fat% in (0,100). Also: Body weight × body-fat % → fat mass and lean mass. Shows fat kg, lean kg, and the same fat % you entered for a quick check.