NFPA in USA

NFPA 13 calculator

Sprinkler System Demand Calculator

Estimate sprinkler demand, hose allowance, and elevation pressure for a simplified system demand check.

Sprinkler SystemsNFPA 13Workpaper

Calculation workpaper

Enter inputs, review outputs, then use the guidance below before carrying the result forward.

US customary units

Calculation inputs

Enter project screening values in the units shown.

Ready

Worksheet header

Optional project fields for keeping the calculation screen traceable.

Results

Ready

Sprinkler demand

225 GPM

Calculated output

Total demand

475 GPM

Calculated output

Elevation pressure

8.66 psi

Calculated output

Sprinkler demand225GPM
Total demand475GPM
Elevation pressure8.66psi

NFPA in USA calculation workpaper

Sprinkler System Demand Calculator

NFPA 13 · Sprinkler Systems

nfpainusa.comGenerated record

Project record

Project ID
Not entered
Area
Not entered
System
Not entered
Revision
Not entered
Prepared by
Not entered
Checked by
Not entered

Inputs

Design density
0.15 GPM/ft²
Remote area
1500 ft²
Hose allowance
250 GPM
Elevation above supply
20 ft

Results

Sprinkler demand
225 GPM
Total demand
475 GPM
Elevation pressure
8.66 psi

Calculation basis

Formula
Demand = density x area + hose allowance
Reference standard
NFPA 13
Professional boundary
Verify adopted code, project criteria, listed equipment data, and AHJ requirements before relying on this record.
NFPA in USAnfpainusa.comThis is a calculation record, not a signed or sealed engineering document.

Calculation basis

Use the formula and linked reference data after the result is visible. Keep input selection separate from the calculation screen.

Formula

Demand = density x area + hose allowance

Nominal Pipe Diameter

Nominal SizeSchedule 10 ID (in)Schedule 40 ID (in)
3/4"0.8840.824
1"1.0971.049
1-1/4"1.4421.38
1-1/2"1.6821.61
2"2.1572.067
2-1/2"2.6352.469

Density and Area Baseline

Hazard ClassificationDensity (GPM/sq ft)Design Area (sq ft)
Light Hazard0.101500
Ordinary Hazard Group 10.151500
Ordinary Hazard Group 20.201500
Extra Hazard Group 10.302500
Extra Hazard Group 20.402500

Use this result

Use total demand and elevation pressure as the demand side of a water supply or pump screen.

Check before use
Confirm hose allowance, remote area, density, and elevation are project-specific.
Common pitfall
Comparing sprinkler-only demand against water supply without hose allowance can understate demand.
Next step
Available Water Supply Calculator

Input evidence

Confirm these values before using the result.

  • Design density (GPM/ft²)
  • Remote area (ft²)
  • Hose allowance (GPM)
  • Elevation above supply (ft)

Authority basis

Check jurisdiction, AHJ, submittal, and edition records before using this result as project evidence.

State and Local Code Adoption WorkflowAHJ Contact ChecklistFire Protection Submittal ChecklistNFPA 13, 72, and 25 Edition Basis Worksheet

Record retention

Save the PDF after project fields, inputs, and results are set.

PDF includes

  • Project header and calculator inputs
  • Computed result rows and warnings
  • Formula, reference basis, and professional boundary

Check before filing

  • Input traceability
  • Method review
  • Output reasonableness
  • Professional boundary

Open next

NFPA 13 Hydraulic Design WorksheetSprinkler Pipe Internal Diameter ReferenceNFPA 13 Sprinkler System Calculators
Engineering disclaimer
NFPA in USA provides engineering workpapers, calculation checks, and reference tables for project screening and coordination. Final design decisions, code interpretations, submittals, and acceptance records must be completed by qualified professionals and verified against the adopted code, project criteria, listings, and Authority Having Jurisdiction requirements. This site does not issue signed or sealed engineering documents.

Related tools and tables

Hazen-Williams Friction Loss CalculatorSprinkler K-Factor Flow and Pressure CalculatorNFPA 13 tool hubSprinkler Pipe Internal Diameter ReferenceNFPA 13 Design Density and Area Reference

FAQ

What is this Sprinkler System Demand calculator for?+
Use it to compute a defined fire protection value from documented inputs, then retain the inputs, result, formula, and warnings with the project record.
Are the results suitable for permit submission?+
Use the saved record only after it is checked against adopted code, project criteria, equipment listings, and AHJ requirements.