Your Body, By the Numbers

Free health calculators that run entirely in your browser. No sign-ups. No data collection. Just the math, the charts, and the honest truth about what your metrics actually mean.

Explore the Tools

Health Data Tools

Seven calculators built for people who want to understand their numbers, not just see them. Every tool stores data locally in your browser.

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BMI Calculator

Calculate your Body Mass Index with instant category visualization and trend tracking over time.

Weight Loss Timeline

Project your weight loss journey with realistic timelines based on your calorie deficit and metabolic data.

Planning

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Body Fat Estimator

Navy method and tape-measure based body fat percentage with visual charts and health category breakdown.

Accuracy

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Ideal Weight Range

Compare four classic formulas (Robinson, Miller, Devine, Hamwi) to find your healthy weight window.

Comparison

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Calorie Needs Calculator

Harris-Benedict and Mifflin-St Jeor equations side by side, with climate and activity adjustments.

Metabolism

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Macro Split Planner

Design your protein, carb, and fat distribution based on your goals, diet style, and training schedule.

Nutrition

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Waist-to-Height Ratio

A simple tape-measure metric that often predicts metabolic risk better than BMI alone.

Screening

Latest From the Blog

Self-experiments, data deep-dives, and the occasional rant about wellness culture — all from East Austin.

Austin Heat Fitness Wearable Lies 2026

My fitness tracker said I burned 4,200 calories yesterday. I was so proud. I posted a screenshot in my group chat. My friend Sarah, who actually knows...

July 23, 2026 Health Data 1,518 words

Austin Heat Fitness Wearable Lies

My Fitness Watch Said I Was 'Overreaching' During Austin's Hottest Week. It Was Wrong. James "Jamie" Whitfield I was halfway through my Tuesday mornin...

July 06, 2026 Health Data 1,518 words

Bmi Normal But Feel Like Garbage

The scale in my bathroom is a liar. Not the digital kind of lie where you shift your weight to the left and shave off two pounds. I mean the deep, str...

July 06, 2026 Health Data 1,518 words

My Fitness Tracker Said I Burned 4200 Calories

My Fitness Tracker Said I Burned 4,200 Calories. My Spreadsheet Said 2,890. The Truth Was Messier. 4,200. That's what my fitness watch told me I burne...

June 24, 2026 Health Data 1,518 words

The Week I Ate Nothing But Food Truck Tacos

The Week I Ate Nothing But Food Truck Tacos — Here's What the Data Said I had a theory. A stupid theory, but a theory nonetheless. I call it the "Aust...

June 23, 2026 Health Data 1,518 words

Can't Afford Wegovy? Here's What the Data Says

I spent two months digging through GLP-1 alternatives. Repurposed generics, supplements, and lifestyle interventions.

June 05, 2026 Health Data 1,518 words

View All 16 Articles

Why BMITool.org Is Different

No sign-ups. No data collection. No "premium tier." Just tools that work.

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100% Private

All calculations happen in your browser. Your data never touches our servers.

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Real Charts

Every tool generates live Canvas/SVG charts — not static images. Save, export, or screenshot them.

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Local History

Your tracking data is saved in your browser's localStorage. Clear it anytime. We can't see it.

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Multiple Formulas

Compare BMI, Navy body fat, four ideal weight formulas, and two calorie equations side by side.

Common Questions

Is my data really private?

Yes. All calculations run in your browser using JavaScript. We don't have a database. We don't use cookies for tracking. We don't even have a server that processes your inputs. If you clear your browser data, your history disappears. That's the point.

Are these tools accurate?

They're as accurate as the formulas they use — which are the same formulas doctors and researchers use. BMI is a screening tool, not a diagnosis. Body fat estimators (like the Navy method) have a margin of error of ±3%. We show you the uncertainty, not just the number.

Why is this free?

I built these tools for myself first. Then I figured other people might find them useful. The site is supported by advertising (clearly labeled) and affiliate links to products I actually use. No paywalls, no "premium features," no data selling.

Read All FAQs →