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Grading & Slope Calculator
Cut/fill volumes and slope %. Estimate site grading work.
Slope % = rise ÷ run × 100. Ratio = run ÷ rise (e.g., 1:12). Angle = atan(rise ÷ run).
Slope
8.33 %
1:12.00 ratio • 4.76°
| Slope % | 8.33 % |
| Ratio | 1:12.00 |
| Angle (degrees) | 4.76° |
warning
ESTIMATE ONLY — not a stamped engineering design. Verify with a licensed PE before procurement or construction.
Methodology
Slope % = rise ÷ run × 100; ratio = run ÷ rise; angle = atan(rise ÷ run) × 180 ÷ π. Cut/fill volume (CY) = area (SF) × depth (ft) ÷ 27. ADA ramp limit from 2010 ADA Standards for Accessible Design §405.2 (max 1:12 / 8.33 %). Compaction shrinkage of 15 % is a planning rule of thumb; actual values depend on soil classification and proctor density — verify with the geotech report.
Frequently Asked Questions
When is fill considered structural?
Fill becomes structural when it supports a foundation, slab, retaining wall, or paved area that has load-bearing requirements. Structural fill must be placed in 8–12 inch lifts and compacted to a specified density — typically 95 % of standard Proctor (ASTM D698) for residential, 98 % modified Proctor (ASTM D1557) for commercial slabs and pavements. Material spec is also tighter: granular soils (sand, gravel, crushed stone) are preferred because they don't change volume with moisture. Organic topsoil, expansive clay, and uncontrolled debris fill are never acceptable as structural fill.
What is a compaction factor?
Compaction factor (also called shrinkage factor) accounts for the difference between loose (bank) volume of soil as excavated and the compacted in-place volume after placement. Typical values: clean sand 5–10 % shrinkage, silty soils 10–15 %, clay 15–25 %, topsoil up to 30 %. If your cut/fill calc shows you need 100 CY of compacted fill, you'll need to bring in roughly 115 CY of bank-measure material from the borrow source. Conversely, excavation produces swell — material expands 15–40 % when loosened, which affects truck count and disposal volumes.
What are the ADA ramp standards?
The 2010 ADA Standards for Accessible Design §405 require ramp running slope no steeper than 1:12 (8.33 %). Cross slope must not exceed 1:48 (2.08 %). Single ramp runs are limited to 30 ft horizontal (30 in of rise) before a level landing of at least 60 × 60 inches is required. Handrails are required on both sides of any ramp with a rise greater than 6 inches. Be aware: the ADA is a federal civil-rights standard; many state and local codes (Texas TAS, California Title 24) impose stricter requirements for accessibility, and historic district approvals may further constrain ramp placement.
What is the difference between gross cut and net cut?
Gross cut is the total volume of material excavated from the site, regardless of where it goes. Net cut is gross cut minus fill placed on the same site — it's what you actually have to haul off. A site with 500 CY of gross cut and 300 CY of fill has a net export of 200 CY. Net is what drives trucking costs; gross drives the bulldozer and excavator hours. Always quote both numbers in earthwork estimates, because the contractor's cost structure depends on both — moving 500 CY internally with a scraper is much cheaper than hauling 500 CY off-site by tandem dump.