Plumbing & Drainage
Convert a chosen slope percentage into the vertical drop over a measured pipe run. The slope itself must come from the project design or applicable requirement.
Change the defaults to match your project and the product you plan to buy.
Project result
See the vertical drop created by the entered percent grade across the measured run.
Planning estimate only. Verify product coverage, package size, supplier specifications and project requirements before purchasing.
Choose the right tool
You already have an approved slope percentage and need vertical drop over a measured horizontal run.
Use Drain Pipe Length for stock footage; this tool does not prescribe required drain slope.
Methodology
slope % ÷ 100
Converts percent grade to rise/run fraction.
run × slope fraction
Same physical units as the run.
1 ÷ slope fraction
Shown as an approximate 1:N reference.
compare endpoints
Use field elevations to verify the planned drop.
Measure the actual developed horizontal run between the two points whose elevation difference you want to check. Do not use a diagonal tape distance when the design slope is defined against horizontal run. Record the starting elevation and planned endpoint independently so the calculated drop can be checked against real site constraints rather than accepted in isolation.
Enter only a slope that has already been selected from the project design, manufacturer instructions or applicable plumbing requirements. Different pipe uses, diameters and jurisdictions can require different minimum or maximum conditions. This calculator is intentionally limited to geometry; it does not approve a drainage layout, venting scheme, trap arrangement or pipe size.
Reference
| Planning item | Starting point | Verify / adjust |
|---|---|---|
| Run | horizontal developed length | Use endpoints of the slope segment. |
| Slope | entered project value | Not prescribed by tool. |
| Drop | run × slope | Check against available elevation. |
| System design | code/project requirement | Separate from geometry. |
Questions
That depends on pipe use, size and applicable requirements; this calculator only converts the slope you enter.
No. Two percent is 0.24 inches per foot, not 2 inches per foot.
Use horizontal run when the slope is defined as vertical change divided by horizontal distance.
Planning guides
Plumbing & Drainage
Convert an already-selected percent slope into vertical drop across a measured horizontal run.
Read guide →Calculate total linear footage from repeated segments and estimate whole stock pieces with an optional waste allowance in US or Metric units.
Open calculator → Plumbing & DrainageConvert measured drain runs into an allowance-adjusted pipe length and whole stock-section count for material planning.
Open calculator → Plumbing & DrainageCalculate approximate internal pipe volume from inside diameter and length, with output in gallons/liters and cubic volume.
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