Fire Alarm Loop Load Calculator
Check device count, loop current, capacity usage, address usage, and spare margin.
Open ToolFire Alarm Battery Calculator
Fire alarm battery calculator for standby and alarm backup planning, including NFPA 72, BS 5839, GCC-style, and Fire-Lite style panel battery checks.
Fire alarm battery and Fire-Lite style panel calculator
This fire alarm battery calculator estimates standby and alarm battery capacity from normal current, alarm current, standby duration, alarm duration, derating, and spare capacity. It can be used for Fire-Lite style panel checks, conventional panels, addressable fire alarm panels, and preliminary ELV battery schedules. The result helps engineers catch undersized battery selections before submittal review. Final fire alarm battery sizing must still follow NFPA 72, BS 5839, authority requirements, temperature derating, manufacturer panel limits, charger capacity, aging allowance, and approved cause-and-effect operation. Load the sample first, then replace the currents with actual panel, NAC, loop, relay, annunciator, and auxiliary device values.
Inputs
Forms are empty on load. Use sample data to preview the workflow or enter your own project values.
Learn more
Formula logic, use cases, assumptions, and limits for this tool.
How this tool helps
Use this to check whether a fire alarm panel battery set has enough standby and alarm capacity. Verify final requirements with project code and panel manufacturer data.
Assumptions and limits
This tool provides a planning-level result. It does not replace detailed engineering design, approved software, manufacturer data, authority requirements, or project specifications.
Typical use cases
- Early estimation and tender support.
- BOQ sanity checking and technical review.
- Site discussion before final engineering verification.
- Comparison of alternatives using consistent assumptions.
Result interpretation
Read the recommendation, warning, and confidence sections together. A result without warnings is still not an approval; it only means the entered values did not trigger built-in planning alerts.
Quick answer for common searches
Fire alarm battery sizing combines standby current, alarm current, standby duration, alarm duration, derating, and spare margin. FireLite or other panel brands still need manufacturer current data.
Useful search phrases covered by this page
- firelite battery calculator
- fire alarm battery calculator
- fire alarm standby battery calculation
Next checks
Input definitions and typical values
These notes explain what each input means and which values usually produce a more reliable planning result.
Standby current A
Electrical current or battery input. Use measured standby/alarm current or manufacturer datasheet values for better results.
Alarm current A
Electrical current or battery input. Use measured standby/alarm current or manufacturer datasheet values for better results.
Standby duration hours
Project input used directly in the calculation. Use measured, scheduled, manufacturer, or authority-approved values where available.
Alarm duration minutes
Project input used directly in the calculation. Use measured, scheduled, manufacturer, or authority-approved values where available.
Usable battery derating %
Electrical current or battery input. Use measured standby/alarm current or manufacturer datasheet values for better results.
Spare capacity %
Future spare capacity. 10-25% is common in early MEP planning, depending on client growth and infrastructure constraints.
Practical verification checklist
- Confirm the selected standard profile is suitable for the project location and authority.
- Replace sample values with project drawings, schedules, equipment data, or measured site values.
- Review warnings, methodology, and PDF report before using the result outside early planning.
- Verify final decisions against official standards, manufacturer data, consultant specifications, and local approvals.
Related tools
Other tools in Fire Alarm.
Fire Alarm DIP Switch Calculator
Convert fire alarm device addresses into DIP switch ON/OFF positions and binary value checks.
Open ToolCalculation methodology
Battery Ah = standby current x standby hours + alarm current x alarm duration, adjusted for derating and spare capacity.
Inputs are treated as planning assumptions. The calculator shows warnings when entered values fall outside practical thresholds or selected standard-profile limits.
Version history
- v1.3.6-prelaunch: Added methodology, standard profile support, version notes, and direct PDF report download.
- v1.3.5: Calculator page added with sample data, warnings, and print-ready report layout.
Stage 2 roadmap: optional saved projects, dashboards, and shared calculation history without forcing login for free use.
Trust and verification
Every result includes assumptions, warning logic, and a downloadable report. Final engineering decisions still need qualified review, local authority approval, manufacturer data, and project specifications.
Worked example
Use the sample data button to load a realistic scenario, then download the PDF report to review inputs, results, methodology, warnings, and disclaimers in one place.