Offline
No internet, no account required.
NFPA 14
Validated against the standard.
PDF export
Pro-only. Generate professional reports.
$2.99 Pro
Lifetime unlock. No subscriptions.
How it works
Enter your values
Type in your inputs — the app fills code tables and constants for you, so there's nothing to look up.
Get a code-checked result
Instant answer with a clear PASS / FAIL and the exact NFPA 14 reference behind every number.
Save & export
Keep a history of calculations and export a clean PDF report to share or attach to a permit (Pro).
What this calculator does
Standpipes deliver water to hose connections throughout a building for the fire department and, in some systems, occupants. This app applies NFPA 14 to determine class, minimum pressures, and the required flow at the hydraulically most remote outlet.
The NFPA 14 essentials
- Class I — 2-1/2 inch connections for fire-department use.
- Class II — 1-1/2 inch connections for trained occupants.
- Class III — both.
- Pressure — a minimum residual of 100 psi at the most remote 2-1/2 inch outlet (Class I/III); 65 psi at a Class II 1-1/2 inch outlet.
- Flow — 500 GPM for the first standpipe plus 250 GPM for each additional, commonly capped around 1,000 to 1,250 GPM.
Worked example
A building with two standpipes needs 500 + 250 = 750 GPM while maintaining 100 psi residual at the top, hydraulically most remote outlet — the demand point the supply or fire pump must meet.
Related calculators
Size the pump to the demand with the fire pump calculator and confirm the source with the water supply calculator.
Standpipe FAQ
What is the minimum standpipe pressure?
Current NFPA 14 requires a minimum residual of 100 psi at the hydraulically most remote 2-1/2 inch outlet for Class I and III systems, and 65 psi at a Class II 1-1/2 inch outlet.
How much flow is required?
500 GPM for the first (most remote) standpipe plus 250 GPM for each additional standpipe, typically not required to exceed about 1,000 to 1,250 GPM total.
What is the difference between the classes?
Class I serves fire departments with 2-1/2 inch outlets, Class II serves occupants with 1-1/2 inch hose, and Class III provides both.
Does it work offline?
Yes, it runs 100% offline with no account. Free with rewarded ads; a one-time $2.99 Pro unlock adds PDF export and saved history.
Get Standpipe on your phone
Free with rewarded ads · $2.99 lifetime Pro · iOS & Android. Works 100% offline on the job site.