# StandbyCalc — UK alarm battery sizing tool

> UK alarm battery sizing tool (iPhone/iPad app by D4N LTD.)

- Source: https://appshunter.io/ios/app/standbycalc/id6761339878 (this page in markdown: same URL + `.md`)
- Developer: [D4N LTD](https://appshunter.io/developer/1212131887)
- Category: Utilities, Productivity
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 4 MB
- Languages: American English
- Released: 2026-04-01
- Data updated: 2026-08-30
- User reviews in markdown: https://appshunter.io/ios/app/standbycalc/id6761339878/reviews.md

## What is StandbyCalc?

StandbyCalc is the fastest way to calculate standby battery requirements for UK fire and intruder alarm systems.

Built for engineers, by engineers. Enter your quiescent and alarm currents, select your system grade or category, and get an instant answer — including which standard battery size you need.

SUPPORTS:
- Intruder alarms — BS EN 50131 / BS 9263, Grades 1-4
- Fire alarms — BS 5839-1:2025, Categories L, M, and P
- Standalone PSUs — custom standby and alarm periods

FREE FEATURES:
- All battery calculations
- All standards and grades
- Save unlimited calculations
- Standard battery size recommendations

PRO UPGRADE (one-time purchase):
- iCloud backup across devices
- PDF reports with full formula working
- Add your company logo and branding
- Share reports via email, AirDrop, or Files
- Professional compliance documentation

Compliant with NSI and SSAIB requirements. Calculations per BS 9263 Annex C and BS 5839-1:2025 Annexe E.

No account required. No subscription. Just open and calculate.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| StandbyCalc Pro | $9.99 | one-time |



## Version history (last 2 releases)

### 1.0.1 — 2026-08-11

Performance improvements and bug fixes.

### 1.0 — 2026-04-01

No release notes.

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## More apps by D4N LTD

- [Laylo](https://appshunter.io/ios/app/laylo/id6761607186)
- [GroundPin: Utility Locator](https://appshunter.io/ios/app/groundpin-utility-locator/id6762096562)

All apps by D4N LTD: https://appshunter.io/developer/1212131887

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-30.*