diff --git a/README.md b/README.md
index 32f95c0..78c0e5c 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,124 @@
-hi
\ No newline at end of file
+# Hiking Difficulty Calculator
+
+A comprehensive tool for calculating hiking trail difficulty based on multiple factors including trail characteristics and personal fitness metrics.
+
+## Installation
+
+1. Ensure you have Python installed on your system
+2. Install the required dependency:
+   ```
+   pip install PyQt5
+   ```
+3. Run the program:
+   ```
+   python fatwalk.py
+   ```
+
+## Features
+
+### Basic Trail Information
+- **Distance (miles)**: Total trail length. For loop trails, enter the full loop distance.
+- **Elevation Gain (feet)**: Total elevation gain over the trail.
+- **Trail Type**:
+  - One Way: Calculates difficulty based on full distance
+  - Loop/Round Trip: Calculates grade using half the distance (as you return to start)
+
+### Personal Metrics
+- **Height (inches)**: Used for BMI calculation
+- **Weight (lbs)**: Used for BMI calculation
+- **Age (years)**: Used for VO2 max calculation
+- **Gender**: Affects VO2 max calculations
+
+### VO2 Max Calculation Methods
+The program offers multiple ways to determine your VO2 max:
+
+1. **Age/RHR Method**: Uses age and resting heart rate
+   - Simplest method
+   - Requires only resting heart rate
+   - Good for quick estimates
+
+2. **Heart Rate Reserve Method**:
+   - More accurate
+   - Requires:
+     - Maximum heart rate
+     - Exercise heart rate
+     - Exercise intensity level
+
+3. **Cooper Test**:
+   - Based on 12-minute run distance
+   - Enter distance covered in meters
+
+4. **Rockport Walking Test**:
+   - Based on 1-mile walk
+   - Requires:
+     - Time to walk one mile
+     - Heart rate at finish
+
+5. **Lab Test Results**:
+   - Direct input of professionally measured VO2 max
+   - Most accurate if available
+
+### Terrain Difficulty Scale (1-10)
+1. Paved road or smooth path
+2. Well-maintained trail, packed dirt
+3. Gravel path with some uneven spots
+4. Natural trail with roots and small rocks
+5. Mixed terrain with moderate obstacles
+6. Rocky trail with frequent obstacles
+7. Rough terrain with loose rocks and steep sections
+8. Technical terrain with scrambling required
+9. Very difficult terrain with constant obstacles
+10. Extreme terrain requiring careful navigation
+
+## How Difficulty is Calculated
+
+### Base Difficulty Factors
+1. **Distance**: Longer trails increase difficulty
+   - Base factor = distance/5
+
+2. **Elevation Gain**: Higher gain increases difficulty
+   - Factor = elevation gain/1000
+
+3. **Grade**: Steeper trails are more difficult
+   - Calculated as (elevation gain/distance)
+   - For loops, uses half distance for more accurate grade
+   - Factor = (grade/10)^1.5
+
+4. **BMI Impact**:
+   - Under 18.5: 1.3x multiplier
+   - 18.5-24.9: 1.0x multiplier (optimal)
+   - 25-29.9: 1.2x multiplier
+   - 30+: 1.4x multiplier
+
+5. **Terrain**: Multiplier based on terrain difficulty selection
+   - Factor = terrain rating/5
+
+### VO2 Max Adjustment
+Your calculated VO2 max adjusts the final difficulty:
+- ≥50: 0.8x (Very fit)
+- 40-49: 0.9x (Above average)
+- 30-39: 1.0x (Average)
+- 20-29: 1.2x (Below average)
+- <20: 1.4x (Poor)
+
+### Final Ratings
+The calculator provides two scores:
+1. Base Difficulty Score (1-10)
+2. VO2 Adjusted Score (1-10)
+
+Rating Scale:
+- 1-2: Easy
+- 3-4: Moderate
+- 5-6: Challenging
+- 7-8: Difficult
+- 9-10: Very Difficult
+
+## Tips for Use
+1. Always enter accurate personal metrics for best results
+2. Use the terrain slider to match actual trail conditions
+3. For loop trails, enter the full loop distance
+4. If available, use lab-tested VO2 max for most accurate results
+5. Consider weather conditions separately as they can significantly affect difficulty
+
+## Note
+This calculator provides estimates based on general factors. Always consider your personal experience, current conditions, and use proper judgment when hiking.
\ No newline at end of file