# Radiator / BTU Calculator — Size your radiator for heat > Calculate radiator BTU and kW requirements for rooms. (iPhone/iPad app by Claire Holmes.) - Source: https://appshunter.io/ios/app/radiator-btu-calculator/id397251605 (this page in markdown: same URL + `.md`) - Developer: [Claire Holmes](https://appshunter.io/developer/397229185) - Category: Utilities, Productivity - Price: $1.99 - Rating: 1.00/5 from 1 App Store ratings · 34 written reviews indexed - Age rating: 4+ - Requires: iOS 10.0 · 40 MB - Languages: American English - Released: 2010-10-19 - Data updated: 2026-06-10 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/radiator-btu-calculator/id397251605/reviews.md ## What is Radiator / BTU Calculator? This application is a must for any plumber, builder or home DIY enthusiast, infact anyone who wants to find out what radiator BTU's are required for a particular room size. Wether you have existing radiators and want to check that they are the correct size or if you are adding a new radiator to a room; this is the application for you. The simple yet intuitive interface allows you the choice of measurements in feet or meters. This calculator has the added benefit of showing you the BTU required and also the kW required - all of which can be stored in the application database so you can refer to them at a later date. No more scraps of paper left lying around. Features that can be adjusted for the BTU calculation include: Room volume Room use Double glazing North facing French windows Flooring Foam-filled or uninsulated cavity walls 2 or 3 outside walls Units of measurement Save your results We have also included a free Celsius to Fahrenheit converter and a gross / net kW/BTU converter. ## Key features - Calculate BTU and kW requirements - Adjust for room volume and use - Account for glazing and wall types - Support for feet or meter measurements - Save and store results - Includes unit converters ## Recent user reviews (10 of 34) All indexed reviews: https://appshunter.io/ios/app/radiator-btu-calculator/id397251605/reviews.md ### 1/5 — Help *2024-09-25, version 7.0.0* Just Purchased App and it will not open? ### 1/5 — Doesn’t Work *2023-06-22, version 7.0.0* I have just paid £1.99 for this and it doesn’t open, please fix ### 3/5 — Good app but won’t open anymore. *2023-03-06, version 7.0.0* Good app but it is no longer opening on iPhone 13pro iOS 16.3.1. Please provide solution ### 1/5 — Don’t spend your money *2022-09-01, version 7.0.0* Should have read the reviews first - just bought it and it doesn’t load. Shame looked like a good - just what I was looking for ### 1/5 — Does not work *2022-06-05, version 7.0.0* Paid to use this app does not work all you get is a picture of a dog ### 1/5 — Useless *2022-05-05, version 7.0.0* Utterly useless ### 1/5 — Useless *2022-02-05, version 7.0.0* I purchased this app. It is not even opening. What a joke. If I could rate something below one, I would rate it. ### 2/5 — Fix please *2021-03-29, version 7.0.0* Was great but won’t open these days. Please fix. ### 1/5 — The app keeps crashing??? Won't start up *2021-03-22, version 7.0.0* The app keeps crashing??? Won't start up ### 4/5 — Please update *2020-09-15, version 7.0.0* Perfect simple little app, nothing else like it, now won’t open at all, imagine needs updating 😩 ## Frequently asked questions about Radiator / BTU Calculator ### What does the Radiator / BTU Calculator app do? This application helps users calculate the necessary BTU (British Thermal Units) and kW (kilowatts) required for a specific room to properly size radiators. It's designed for plumbers, builders, and DIY enthusiasts who need to ensure adequate heating for a space. ### What factors can I adjust for the BTU calculation? You can adjust for various factors including room volume, room use, presence of double glazing, whether the room is north-facing, French windows, flooring type, wall insulation (foam-filled or uninsulated cavity walls), and the number of outside walls (2 or 3). You can also choose your preferred units of measurement. ### Is this app free to use? Yes, the application is available for free. There are no in-app purchases or advertisements mentioned, indicating a completely free user experience. ### Can I save my calculations? Yes, the app allows you to save your calculated BTU and kW requirements directly within the application's database. This feature helps you keep track of your heating calculations without needing to write them down on scraps of paper. ### What other tools are included in the app? In addition to the main BTU calculator, the app includes a free Celsius to Fahrenheit converter and a gross/net kW/BTU converter. These tools provide further utility for heating-related calculations and conversions. ## Version history (last 5 releases) ### 7.0.0 — 2019-09-15 Completely redesigned interface for all screen sizes. Added handy gross / net BTU/KW conversion tool. Added handy Celsius to Fahrenheit conversion tool. NOTE - Please backup or take a note of your saved results before updating. ### 006 — 2016-01-14 Made compatible with latest iOS version = Please backup or take a note of your saved results before updating. ### 003 — 2011-01-06 Added in additional room features such as : Solid floors Foam-filled and uninsulated cavity walls 2 or 3 outside walls. Additional functionality allows for greater flexibility and hence greater accuracy. Calculator is now in a scrollable window due to extra content. Updated the About page. Please take a note / backup of your saved results incase there should be any loss of result data before updating. ### 002 — 2010-12-02 Shake to clear function - Added in ability for user to shake and clear the inputs. Application now remembers the last units of measurement used. Save function - You can now to save any of your results allowing you to refer to them at a later time or date. Saved Results List - Previously saved items can be deleted to remove results which are no longer required. ### 001 — 2010-10-19 No release notes. ## Apps similar to Radiator / BTU Calculator | App | Rating | Price | Category | | --- | --- | --- | --- | | [McAfee: Stay Secure & Private](https://appshunter.io/ios/app/mcafee-stay-secure-and-private/id724596345) | 4.7 (229,190) | Free | Utilities | | [Opensignal Speed Test Ad Free](https://appshunter.io/ios/app/opensignal-speed-test-ad-free/id598298030) | 4.5 (17,357) | Free | Utilities | | [Sound Meter HQ](https://appshunter.io/ios/app/sound-meter-hq/id1093419762) | 4.8 (327) | Free | Utilities | | [AdBlocker: AdBlock for Safari](https://appshunter.io/ios/app/adblocker-adblock-for-safari/id1514739120) | 4.5 (5,825) | Free | Utilities | | [Cubic Yards Calculator + Cost](https://appshunter.io/ios/app/cubic-yards-calculator-plus-cost/id1494938402) | 4.7 (815) | Free | Utilities | | [Duct Calculator](https://appshunter.io/ios/app/duct-calculator/id1587860308) | 1.0 (1) | Free | Utilities | ## More apps by Claire Holmes - [Carpet calculator / estimator](https://appshunter.io/ios/app/carpet-calculator-estimator/id406825264) - [Clapperboard / Clapboard Slate](https://appshunter.io/ios/app/clapperboard-clapboard-slate/id411034432) - [Gas Rate Heat Input Calculator](https://appshunter.io/ios/app/gas-rate-heat-input-calculator/id415565802) - [Pipe Offset Calculator](https://appshunter.io/ios/app/pipe-offset-calculator/id426519976) - [BMI Calc - Body Mass Index](https://appshunter.io/ios/app/bmi-calc-body-mass-index/id438060833) All apps by Claire Holmes: https://appshunter.io/developer/397229185 --- *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 2026-06-10.*