Engineering Calculators
BS 5839-1 aligned calculators. Built for the work you do every day.
The Engineer Toolkit provides a suite of calculators for the most common fire alarm engineering calculations — battery standby capacity, detector spacing, cable resistance, voltage drop, PSU load, loop capacity, SPL levels, and Ohm's Law.
Each calculator follows BS 5839-1 guidance and EN 54-4 principles. Inputs are clearly labelled with standard references. Results are presented with notes on what to verify against current standards and manufacturer specifications.
The toolkit is designed for use on-site and in the office. All calculators work offline once the app is loaded.
Engineering use cases
Real examples from the work fire alarm engineers do every day.
Standby battery sizing for a panel upgrade
Input total current draw and required standby duration. Calculator returns minimum battery capacity per EN 54-4, with worked figures to include in the design record.
Detector spacing on an awkward floor plate
Input room dimensions and ceiling height. Calculator returns maximum device spacing per BS 5839-1 Table 4, flagging any constraints from ceiling pitch or obstructions.
Cable resistance check before commissioning
Input cable length, CSA, and device loop. Calculate end-of-line resistance to verify it falls within panel specification before commissioning.
Key benefits
- ✓10 calculators covering the most common engineering calculations
- ✓BS 5839-1 and EN 54-4 aligned with standard references shown
- ✓Works offline — no internet needed on site
- ✓Results formatted for inclusion in design records
Start using Engineering Calculators today
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