# BMR Calculator

## Overview
Calculate Basal Metabolic Rate using three established formulas with activity level TDEE estimates.

## Features
- Calculate BMR using Mifflin-St Jeor formula (recommended)
- Calculate BMR using Harris-Benedict (revised) formula
- Calculate BMR using Katch-McArdle formula (requires body fat %)
- Compare results across all three formulas
- Estimate Total Daily Energy Expenditure (TDEE) at five activity levels
- Support for metric (cm/kg) and US (ft+in/lbs) unit systems
- Export results as PDF

## Inputs
- Gender (Male/Female)
- Age (15-120 years)
- Height (cm or ft+in)
- Weight (kg or lbs)
- Body Fat % (optional, enables Katch-McArdle)

## Outputs
- Primary BMR value (Mifflin-St Jeor)
- Formula comparison table (all applicable formulas)
- TDEE estimates at 5 activity levels (Sedentary through Extra Active)

## Formulas
Mifflin-St Jeor:
- Male: BMR = 10W + 6.25H - 5A + 5
- Female: BMR = 10W + 6.25H - 5A - 161

Harris-Benedict (revised):
- Male: BMR = 13.397W + 4.799H - 5.677A + 88.362
- Female: BMR = 9.247W + 3.098H - 4.330A + 447.593

Katch-McArdle:
- BMR = 370 + 21.6 * LBM (lean body mass = weight * (1 - bodyFat/100))

(W = weight in kg, H = height in cm, A = age in years)

## Use Cases
- Understanding baseline calorie needs
- Fitness and nutrition planning
- Comparing formula accuracy for your body type
- Estimating daily calorie burn at different activity levels