Calculator
Engineering
MathGrade Calculator
Free online grade calculator for land grading, site work, and elevation changes. Calculate grade percentage, slope, and elevation differences for drainage, roads, and landscaping projects.
What is Grade (Land Grading)?
Grade refers to the slope of the ground surface, measured as elevation change over horizontal distance. Proper grading is essential for water drainage, preventing foundation problems, erosion control, and creating usable outdoor spaces. Positive grade slopes away from buildings to prevent water infiltration. Grading plans show existing grade (natural terrain) and proposed grade (after site work) with cut (excavation) and fill (added material) areas. Professional grading ensures compliance with drainage codes and prevents water-related issues.
Grade Calculation Formulas
1. Grade % = (Elevation Change / Horizontal Distance) × 100
2. Elevation Change = Horizontal Distance × (Grade % / 100)
3. Distance = Elevation Change / (Grade % / 100)
4. Angle = arctan(Grade % / 100)
Grade Standards
Away from building: 2-5% minimum (first 10 feet)
Lawn/landscape: 2-3% for drainage
Driveway: 1-2% minimum, 15% maximum
Road: 0.5% minimum, 6-10% typical, 15% maximum
Parking lot: 1-5% for drainage
Sidewalk: 1-2% cross slope, 5% maximum running slope
Drainage swale: 1-6%
Types of Grading
Rough Grading: Initial earthwork, establishing basic slopes and drainage patterns
Fine Grading: Final surface preparation before landscaping or paving
Positive Drainage: Sloping away from structures (minimum 2% for first 10 feet)
Swales: Shallow channels for surface water drainage (1-6% grade)
Terracing: Creating level areas on steep slopes with retaining walls
Applications
- Site preparation: Foundation drainage, building pad elevation
- Landscaping: Lawn drainage, garden beds, hardscaping
- Roads & driveways: Safe vehicle access, water runoff
- Sports fields: Proper drainage for playability
- Parking lots: Surface drainage, ADA compliance
- Erosion control: Preventing soil loss on slopes
- Stormwater management: Directing runoff to collection systems
Tips for Land Grading
- Minimum 2% grade away from buildings for at least 10 feet
- Steeper grades (>4:1 or 25%) may require retaining walls or terracing
- Consider existing trees and vegetation - grading can damage roots
- Account for soil compaction - fill areas settle 10-20%
- Ensure positive drainage at all points - no ponding areas
- Check local codes for grading permits and requirements
- Professional survey recommended for complex grading projects
Drainage Guidelines
Effective drainage requires proper grading. Minimum grades: 2% away from foundations (1/4 inch per foot for first 10 feet minimum), 1-2% for lawns and landscaping, 0.5-1% for paved surfaces. Avoid flat areas (0% grade) where water can pond. Maximum grades depend on use: 33% (3:1) for mowed grass slopes, 50% (2:1) for unmowed slopes, steeper requires retaining walls. Swales should be 1-6% grade. Always direct water away from foundations and toward appropriate drainage systems or natural waterways.