PSI vs GPM Calculator

There’s no universal PSI→GPM conversion. But for the same nozzle/orifice, you can estimate flow changes with: Q₂ = Q₁ × √(P₂ / P₁). Use this page to estimate GPM at a new PSI (or required PSI for a target flow).

Best practice: estimate here → verify output with Nozzle Flow Rate → compute spray rate with Calibration → mix with Spray Mix Calculator.

How to estimate flow at a different pressure

  1. Get a baseline: Find a baseline flow (GPM or L/min) at a baseline pressure (PSI or bar) from a nozzle chart or a catch test.
  2. Enter baseline values: Enter the baseline pressure and baseline flow per nozzle.
  3. Enter your target: Choose Pressure → Flow to estimate output at a new pressure, or Flow → Pressure to estimate required pressure.
  4. Verify when needed: Real nozzle pressure can differ due to losses. Confirm with a catch test for accuracy.

Measure baseline output here: Nozzle Flow Rate Calculator.

Calculator

Pressure ↔ Flow Reference (Same Nozzle)

Enter a baseline flow and pressure from a nozzle chart (or a catch test). Then calculate the flow at a new pressure, or the pressure needed for a target flow. Includes bar and L/min conversions.

Accuracy note: regulator settings, hose losses, clogged strainers, and nozzle wear can change real nozzle pressure/flow. Use a catch test to confirm real output.

Quick reference: how flow changes with pressure

For the same nozzle, flow scales with the square root of pressure: Q ∝ √P. Values below are approximate multipliers.

Pressure change Flow multiplier Example (0.20 GPM baseline)
+25% pressure (× 1.25) × 1.118 ≈ 0.224 GPM
+50% pressure (× 1.50) × 1.225 ≈ 0.245 GPM
Double pressure (× 2.00) × 1.414 ≈ 0.283 GPM
Half pressure (× 0.50) × 0.707 ≈ 0.141 GPM

If you need actual output (not an estimate), do a catch test using Nozzle Flow Rate.

Recommended gear (optional)

This workflow is easier with stable pressure and accurate measurement:

Related calculators

FAQ

Is there a universal PSI to GPM conversion?

No. Flow depends on nozzle/orifice size and design. This page estimates how flow changes with pressure for the same nozzle using Q₂ = Q₁ × √(P₂/P₁).

If I double PSI, do I double GPM?

No. Doubling pressure increases flow by √2 (about 1.41×) for the same nozzle.

How do I estimate required PSI for a target flow?

Use P₂ = P₁ × (Q₂/Q₁)². This calculator computes it when you enter a baseline and a target flow.

Should I trust the result exactly?

Treat it as an estimate. Pressure at the nozzle can differ from gauge pressure due to losses and restrictions. Verify output with a catch test if accuracy matters.