Our process

A number is only useful if you can trust where it came from.

Every calculator on this site goes through the same four-step process before it’s published. Here’s what actually happens at each step.

Start from the research

We pull ranges from bodies like the National Academies, the ISSN, and peer-reviewed studies — not blog-post averages.

Show a range, not a lie

Real biology varies by person. Every result is a range with a practical midpoint, never a single falsely precise digit.

Test the edges

We check empty fields, unit switches, and extreme inputs so the tool never shows a broken or misleading number.

Say what it isn’t

Every calculator is clearly labeled as an estimate for generally healthy adults — not a diagnosis or medical advice.

Where our numbers come from

We don’t average opinions from fitness blogs or repeat whatever number shows up most often in search results. Every range starts with a specific, named source: a dietary reference intake report, a position stand from a sports-nutrition or medical organization, or a peer-reviewed study. If we can’t point to where a number came from, it doesn’t go on the site. Every calculator page links directly to the sources it’s built on, so you can check our work instead of taking our word for it.

Why we show a range, not a single number

A tool that outputs “147 grams” looks precise, but that precision is mostly fake — individual protein needs, calorie needs, and body composition all vary based on factors a five-field form can’t fully capture. Instead, every calculator here reports a low–high range grounded in the cited research, plus a practical midpoint you can actually use day to day. The range is the honest answer; the midpoint is the practical one.

How we test every calculator

Before anything is published, we run it against a checklist that includes:

Multiple realistic user scenarios, checked by hand against the underlying formula
Empty, zero, negative, and extreme input values, to confirm nothing breaks or shows NaN, undefined, or Infinity
Unit conversions in both directions (kg ⇄ lb, cm ⇄ ft/in), including switching units after a value is already entered
Keyboard-only navigation and screen-reader labeling, so the tool works without a mouse
Mobile, tablet, and desktop layouts, to confirm nothing overflows or becomes unusable

If a calculator can’t pass all of these, it doesn’t ship yet.

What we won’t do

A few things we hold ourselves to, even when it would be easier not to:

We won’t invent a source or cite a study we haven’t actually read.
We won’t present a number as more precise or more certain than the underlying research supports.
We won’t use fear-based language (“you’re not eating enough protein!”) to drive engagement.
We won’t require an account, an email address, or any personal data to use a calculator.
We won’t recommend a specific supplement or product based on your result.

Medical disclaimer

Every calculator on ToolsToHealth provides general, evidence-informed estimates for generally healthy adults. None of them are medical devices, and none of their output is a diagnosis or a prescribed treatment plan. If you have a health condition that affects nutrition or metabolism, talk to a doctor or registered dietitian about numbers specific to you.