Percentages, Slope & Grade
Percentages run through grading, slope, waste factors, and pricing.
Percent grade = rise ÷ run × 100 · 2% typical pavement cross slope · ADA ramp 1:12 (8.33%) · ADA cross slope ≤ 2% · waste factor: multiply by (1 + waste %) · percent of: decimal × number.
Worked examples
- A pipe dropping 2 ft over 100 ft = 2% grade; over a 50-ft run that’s a 1-ft drop.
- 15% of 800 = 0.15 × 800 = 120.
- 1,000 sq ft + 10% waste = 1,100 sq ft to order.
- A walkway at a 2% cross slope drops 0.2 ft (about 2.4 in) over 10 ft.
Slope ratios like 1:12 mean 1 unit of rise per 12 units of run — the ADA ramp limit you’ll meet in paving and accessibility work.
Practice: Percentages, Slope & Grade
Frequently asked
How do you calculate percent grade?
How do you add a waste factor?
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