PSI to GPM Calculator — Advanced Flow Tools

Input

Pressure (PSI) Gauge pressure at the device.

Method Choose based on known data for your device.

Decimals

Result

Method	PSI	Parameters	GPM
No calculation yet. Enter inputs and press Calculate.

Result rounded to selected decimal places.

Formula used

Sprinkler/Nozzle K‑factor: GPM = K × √(PSI)

Valve flow coefficient (Cv): GPM = Cv × √(PSI / SG)

Orifice equation (US units): GPM = 29.84 × C_d × d² × √(PSI / SG), where d is in inches. This comes from Bernoulli with imperial unit conversions.

Units & assumptions

PSI is pressure at the device inlet.
SG is fluid specific gravity (water ≈ 1 at room temperature).
C_d depends on geometry: sharp‑edged orifice ≈ 0.62, full‑bore nozzle ≈ 0.95–1.0.

Example data

PSI	Method	Parameters	GPM
30	K	K=5.6	30.672
50	K	K=8.0	56.569
40	CV	Cv=7.5; SG=1	47.434
60	CV	Cv=12; SG=1.1	88.626
45	ORIFICE	d=0.5 in; Cd=0.62; SG=1	31.027
80	ORIFICE	d=0.75 in; Cd=0.95; SG=1	142.623

Examples assume steady flow and the stated parameters.

How to use this calculator

Enter the available pressure in PSI at your device.
Select the method based on what you know:
- K‑factor if the nozzle or sprinkler K is provided.
- Cv if you have a valve datasheet.
- Orifice if you know diameter and discharge coefficient.
Fill in the required parameters for the chosen method.
Click Calculate. The result appears in the table; export as CSV or PDF if needed.
Adjust decimals using the Decimals field to control rounding.

Tip: For water, using SG = 1 is usually sufficient.

FAQs

1) Can PSI and GPM be converted directly without any other information?

No. You need device characteristics such as K‑factor, valve Cv, or effective orifice area via diameter and C_d. This calculator supports all three approaches.

2) What K‑factor should I use?

Use the value stamped on the nozzle or in the sprinkler datasheet. Common values range from 2.8 to 11.2 for standard devices.

3) What is Cv and where do I find it?

Cv is the valve flow coefficient published by the manufacturer. It represents GPM through the valve at 1 psi pressure drop for water.

4) How do I choose C_d for the orifice method?

Use ≈0.62 for a sharp‑edged orifice, ≈0.95–1.0 for well‑designed nozzles. If unknown, 0.62 is a conservative estimate.

5) Does fluid temperature matter?

Temperature slightly changes density and viscosity. The formulas here use SG to account for density. For most water applications within typical temperatures, SG ≈ 1 is adequate.

6) Are friction losses in pipes included?

No. These formulas calculate flow at the device for the given pressure. Pipe friction, fittings, and elevation changes should be analyzed separately, e.g., with Hazen‑Williams or Darcy‑Weisbach methods.