StandbyCalc
UK alarm battery sizing tool
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
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.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Performance improvements and bug fixes.
The developer, D4N LTD, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
- Usage Data
Data Linked to You
The following data may be collected and linked to your identity:
- Identifiers
- Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- D4N LTD
- Size
- 4.2 MB
- Category
- Utilities
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Contains
Advertising
- In-App Purchases
Yes
- StandbyCalc Pro $4.99
- Copyright
- © 2026 D4N LTD