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Grading Calculator

Calculate slopes, grades, and elevation changes for site grading projects.

Leave blank for recommended
Typical: 1.5-2%

Results

Grade & Slope Reference

Application Min Slope Max Slope Typical
Parking lot cross slope 1.0% 5.0% 1.5-2%
Lawn away from building 2.0% 10.0% 2-5%
Swale (turf) 1.0% 4.0% 2%
Concrete sidewalk 0.5% 2.0% 1-2%
ADA ramp (max) - 8.33% 6-8%
Driveway (residential) 1.0% 15.0% 5-8%
Road longitudinal 0.5% 12.0% 2-6%
Flat roof drainage 1/4"/ft 1/2"/ft 1/4"/ft (2%)

Slope Conversion Quick Reference

  • 1% grade = 1 ft rise per 100 ft = 0.12 in/ft
  • 2% grade = 2 ft rise per 100 ft = 1/4 in/ft
  • 4% grade = 4 ft rise per 100 ft = 1/2 in/ft
  • 8.33% = 1:12 ratio (ADA max ramp slope)
  • 25% = 1:4 ratio = 14° angle
  • 50% = 1:2 ratio = 26.6° angle
  • 100% = 1:1 ratio = 45° angle