Radisize: Radiator Calculator
Room-by-room radiator sizing
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Size radiators room-by-room in seconds. Get clear BTU/kW requirements and export professional PDF reports — all calculated offline.
Radisize is the modern way to calculate the correct radiator size for every room in your home or project. Whether you are renovating, upgrading your heating system, or working professionally, Radisize gives you clear BTU and kW requirements based on real room details.
Simply add a property, enter each room’s dimensions, glazing, walls, and floor materials, and Radisize automatically calculates the radiator output needed at either ΔT35 or ΔT50. All calculations are done offline on your device.
FEATURES
• Room-by-room radiator sizing
Enter room type, dimensions, glazing and materials to get accurate BTU and kW requirements.
• Multiple properties
Create and manage as many properties as you need for your home, rentals, or client work.
• Guided room setup
A simple three-step wizard makes entering each room’s details quick and easy.
• Accurate BTU and kW outputs
Calculations use realistic heat-loss logic and your preferred radiator rating (ΔT35 or ΔT50).
• Customisable settings
Choose metres or feet, set your default ΔT, adjust the safety factor, and pick light, dark or system theme.
• Professional PDF reports
Export clean, organised reports for an entire property containing every room’s radiator requirement. Ideal for planning, quotes and documentation.
• Offline-first
No account, no internet, no data sent anywhere. Everything is calculated locally on your device.
WHO IT'S FOR
Homeowners and DIY renovators
Plan heating upgrades confidently, understand your home’s requirements, and choose the right radiators without guesswork.
Heating engineers and installers
Get quick on-site estimates, generate structured PDF reports, and keep multiple properties organised.
WHAT RADISIZE CONSIDERS
• Room dimensions (metres or feet)
• External wall count
• Wall construction type
• Floor and ceiling types
• Glazing area and window type
• Safety factor
• ΔT35 or ΔT50 radiator rating
Every detail is used to provide a more reliable radiator requirement.
Radisize offers a clean and modern design that makes complex heating calculations simple and approachable for everyone.
No subscriptions. No login. No hassle. Just fast, clear radiator sizing.
Use of this app is subject to Apple’s Standard Licensed Application End User License Agreement (EULA), available in the App Store under “License Agreement” and at https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Download Radisize today and find the right radiator size for every room.
Disclaimer: Radisize provides estimation guidance only. Results are approximate and do not replace professional design or safety advice. Always consult a qualified heating engineer and follow local building regulations before purchasing or installing any heating equipment.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
This update introduces Radisize Pro, a one-time upgrade that unlocks unlimited properties, rooms and PDF export. It also includes performance improvements and bug fixes.
The developer, Zippy IT Solutions 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 Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Zippy IT Solutions Ltd.
- Size
- 50.7 MB
- Category
- Utilities
- Compatibility
Requires iOS 13.0 or later.
- iPhone
Requires iOS 13.0 or later. - iPad
Requires iPadOS 13.0 or later. - iPod touch
Requires iOS 13.0 or later. - Mac
Requires macOS 11.0 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+
- In-App Purchases
Yes
- Radisize Pro $2.99
- Copyright
- © 2025 Zippy IT Solutions Ltd.
