Pressure Drop Calculator

Water is lazy and heavy. Pushing it through a narrow, long or fitting-packed pipe costs pressure - and every elbow, valve and rise in elevation takes its cut before the water reaches a fixture.

Pressure Drop Calculator adds straight-pipe friction, fittings and valves, and elevation into one pressure budget, then shows what remains at the outlet.

• Straight pipe friction: Hazen-Williams loss for the run.
• Fittings & valves: Count elbows, tees, gates, globes, balls and checks.
• Elevation change: Rises subtract, descents add back.
• Remaining pressure: Inlet minus total drop.
• Verdict: Enough head left for the fixture?
• Export: Copy or download the report.

1. Enter the flow rate and pipe internal diameter.
2. Enter the pipe length and material C factor.
3. Count the fittings and valves on the run.
4. Enter any net elevation rise (negative for descents).
5. Optional: give the inlet pressure for the remaining-pressure verdict.

Example - Long bathroom feed. 8 GPM in a 3/4 in copper line 60 ft long with eight 90-degree elbows and one gate valve: friction and fittings together cost roughly 5-9 PSI over the run plus any elevation - often the difference between a strong shower and a drizzle.

• See where the pressure goes: friction, fittings and rise separated.
• Catch starved fixtures early: before pipe is in the wall.
• Compare sizes and routes: try a bigger pipe on paper.
• Free and private: no uploads, no logging.