Building an open‑source TDEE calculator you can actually verify

Description and use

An open‑source TDEE calculator with verified formulas and a zero‑permission Firefox extension, enabling easy integration into other projects.

Problem

Existing online TDEE calculators are opaque, ad‑laden, and hard to reuse in other projects.

Outcome

The project delivers a lightweight, open‑source TDEE calculator that can be easily integrated into other applications, with full test coverage and a privacy‑friendly browser extension.

Workflow

• 1. Extract BMR formulas (Mifflin‑St Jeor, Katch‑McArdle, Harris‑Benedict).
• 2. Implement TDEE as BMR × activity multiplier.
• 3. Add macro‑split logic with fixed fat percentage and protein per kg.
• 4. Write unit tests against hand‑derived reference values.
• 5. Publish @aadifit/tdee‑calc to npm.
• 6. Wrap the same formulas in a Firefox extension with a popup UI and a zero‑permission manifest.
• 7. Provide documentation and example usage in the README.

Evidence

Every TDEE calculator I found online was the same thing: a form behind a wall of ads, math you can't see, and no way to reuse it in your own project.

Source

The package @aadifit/tdee-calc – zero dependencies, ~150 lines, MIT licensed, every formula checked against hand‑derived reference values in the test suite (16 tests).

Source