How It Works

Q: Are HealthCalc calculators accurate?

Our calculators use peer-reviewed formulas like Mifflin-St Jeor, Katch-McArdle, and the WHO BMI classification. They provide reliable estimates, but they are not a substitute for professional medical diagnosis.

Q: Is HealthCalc free to use?

Yes. All 34 calculators, the health dashboard, history tracking, and PDF reports are completely free. No account is required.

Q: How is my data stored?

All calculations happen in your browser. We do not send your health data to any server. Saved results are stored locally in your browser's localStorage or tied to your optional account.

3 Simple Steps

1

Enter Your Data

Input basic measurements like weight, height, age, gender, and activity level. Takes less than 30 seconds.

2

Get Instant Results

Our calculators use clinically validated formulas to compute your results in real time, right in your browser.

3

Take Action

Get personalized health improvement tips, save your results, download PDF reports, and track your progress over time.

What Makes Us Different

Your health data never leaves your device. All calculations happen in your browser.

Unlike many health calculators that send your data to a server, HealthCalc runs entirely in your browser. Your measurements are processed locally using JavaScript and are never transmitted over the internet. You can even use our tools offline once the page has loaded.

We use peer-reviewed, clinically validated formulas that doctors and dietitians actually use. No guessing, no rounding, no simplified approximations.

Formulas We Use

Every calculator on HealthCalc is backed by published scientific research. Here are the key formulas:

BMI (Body Mass Index)

BMI = weight (kg) ÷ height² (m²)
Classification per WHO guidelines:
• Underweight: < 18.5
• Normal: 18.5 - 24.9
• Overweight: 25 - 29.9
• Obese: 30+

BMR (Basal Metabolic Rate)

Mifflin-St Jeor Equation:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161

TDEE (Total Daily Energy Expenditure)

TDEE = BMR × Activity Multiplier
Sedentary (office job): × 1.2
Light (1-3 days/week): × 1.375
Moderate (3-5 days/week): × 1.55
Active (6-7 days/week): × 1.725
Very Active (athlete): × 1.9

Body Fat (US Navy Method)

Men: BF% = 495 / (1.0324 - 0.19077 × log(waist - neck) + 0.15456 × log(height)) - 450
Women: BF% = 495 / (1.29579 - 0.35004 × log(waist + hip - neck) + 0.22100 × log(height)) - 450

Water Intake

Base: weight (kg) × 0.033 = liters per day
Adjusted upward for exercise, heat, pregnancy, and breastfeeding.

See all formulas and sources →

Our 34 Health Tools

⚖

BMI Calculator

Body Mass Index

💧

Water Intake

Daily hydration goal

🍳

Calorie Needs

BMR & TDEE

🍦

Macro Calculator

Protein, carbs, fat

🩹

Body Fat %

Navy method

⏰

Heart Rate Zones

Training targets

💪

Ideal Weight

Multiple formulas

💤

Sleep Cycles

Optimal schedule

🍟

Keto Calculator

Keto macros

💰

Calorie Deficit

Weight loss plan

🧑

Lean Body Mass

Muscle vs fat

🏃

VO2 Max

Cardio fitness

💃

Running Pace

Speed & time

🧠

Metabolic Age

Compare to actual

🎅

Pregnancy Due Date

Estimate delivery

🍴

Cholesterol Ratio

Heart health

🩸

Blood Pressure

Category check

💫

Diabetes Risk

Risk assessment

See all 34 calculators →

Frequently Asked Questions

Are HealthCalc calculators accurate?

Our calculators use peer-reviewed formulas like Mifflin-St Jeor, Katch-McArdle, and the WHO BMI classification. They provide reliable estimates, but they are not a substitute for professional medical diagnosis.

Is HealthCalc free to use?

Yes. All 34 calculators, the health dashboard, history tracking, and PDF reports are completely free. No account is required.

How is my data stored?

All calculations happen in your browser. We do not send your health data to any server. Saved results are stored locally in your browser's localStorage or tied to your optional account.

Can I use HealthCalc offline?

Yes. Once the page loads, all calculators work offline. Your results are stored locally in your browser, so you can access saved results without an internet connection.

Can I embed calculators on my website?

Yes. We offer a free embed widget that lets you add any calculator to your own website. Visit our widget page for the embed code.

Do I need to create an account?

No. You can use all calculators anonymously. Creating a free account lets you save results to your history and track progress over time (saved on your current device only).

3 Simple Steps

Enter Your Data

Get Instant Results

Take Action

What Makes Us Different

Formulas We Use

BMI (Body Mass Index)

BMR (Basal Metabolic Rate)

TDEE (Total Daily Energy Expenditure)

Body Fat (US Navy Method)

Water Intake

Our 34 Health Tools

Frequently Asked Questions

Ready to Get Started?