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Drain Slope and Elevation Calculator

Compare measured drain fall with a reviewed slope criterion, then calculate required layout fall and available elevation without assuming a code rule.

Use this result well

Inputs that matter
Reviewed slope requirement and source, Horizontal run (ft), Signed fall in intended flow direction (in), Reviewed minimum slope (in/ft), and 4 more
Output to expect
Measured drain slope, Fall and elevation allowance
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Measured drain slope

Compare signed vertical fall with horizontal run using a slope criterion you have already verified for the actual pipe, application, jurisdiction and adopted code. This geometry check does not supply a universal minimum.

Slope in/ft = signed fall inches / horizontal run feet; slope percent = 100 × fall inches / (12 × run feet).

Fall and elevation allowance

Translate a reviewed target slope into required fall and compare it with the available elevation budget. Include fittings, structural restrictions and tie-in elevations in the reviewed layout.

Required fall inches = horizontal run feet × target inches per foot; remaining elevation = available fall − required fall.

Updated: September 2026

Example Scenarios

Try this example to see the calculation, then enter actual documented values and preserve the measurement conditions. A failed or unresolved comparison is part of the record.

→ 0.25 in/ft · meets entered minimum

Try this example to see the calculation, then enter actual documented values and preserve the measurement conditions. A failed or unresolved comparison is part of the record.

→ 6 in required fall

FAQ

Compare signed vertical fall with horizontal run using a slope criterion you have already verified for the actual pipe, application, jurisdiction and adopted code. This geometry check does not supply a universal minimum. Translate a reviewed target slope into required fall and compare it with the available elevation budget. Include fittings, structural restrictions and tie-in elevations in the reviewed layout.

Use the exact equipment data, measurement point, operating conditions and units described in the selected mode. Record source documents, dates and unresolved conditions in Sources and assumptions. Built-in examples illustrate arithmetic; they are not manufacturer ratings or approved designs.

Use Save planning case for an explicit local history entry. Copy MD keeps current inputs and notes; Download CSV exports the result breakdown. Export portable copies before clearing storage and save a separate case after changing equipment, conditions or measurements.

About Drain Slope and Elevation Calculator

Compare signed vertical fall with horizontal run using a slope criterion you have already verified for the actual pipe, application, jurisdiction and adopted code. This geometry check does not supply a universal minimum. Translate a reviewed target slope into required fall and compare it with the available elevation budget. Include fittings, structural restrictions and tie-in elevations in the reviewed layout.