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NFPA 13
Validated against the standard.
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$2.99 Pro
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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 13 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
Sprinkler pipe has to be supported at the right intervals so it cannot sag or shift. This app returns the maximum hanger spacing and minimum rod size for a pipe by material and diameter, straight from the NFPA 13 support tables.
The spacing rules
- Steel pipe — maximum 12 ft between hangers for 1 inch and 1-1/4 inch, and 15 ft for 1-1/2 inch and larger.
- Copper tube — closer spacing than steel, by size.
- CPVC — closest spacing of all (often 5.5 to 10 ft), since it is more flexible.
- A hanger is also required within a set distance of the end of a branch line and at each change of direction.
Worked example
A run of 2-inch steel branch line can space hangers up to 15 ft apart; the same nominal size in CPVC must be supported far more often, which the app shows side by side.
Related calculators
Size the pipe with the pipe schedule calculator and verify flow with the sprinkler hydraulic calculator.
Hanger spacing FAQ
What is the maximum hanger spacing for steel pipe?
Under NFPA 13, steel pipe is supported at most every 12 ft for 1 inch and 1-1/4 inch, and every 15 ft for 1-1/2 inch and larger.
Why does CPVC need closer hangers?
CPVC is more flexible than steel and sags more under heat and load, so NFPA 13 requires noticeably closer hanger spacing for it.
Does it give rod size too?
Yes. It returns the minimum hanger rod diameter for the pipe size along with the maximum spacing.
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.
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