# Ohm's Law & Power Law Calculator > Electrical calculator for Ohm's Law and Power Law relationships. (iPhone/iPad app by Cressall Resistors Ltd.) - Source: https://appshunter.io/ios/app/ohms-law-and-power-law-calculator/id592763080 (this page in markdown: same URL + `.md`) - Developer: [Cressall Resistors Ltd](https://appshunter.io/developer/592763083) - Category: Utilities, Business - Price: Free - Rating: 4.40/5 from 26 App Store ratings · 71 written reviews indexed - Age rating: 4+ - Requires: iOS 8.0 · 1 MB - Languages: American English, French (France), German (Germany), Hindi, Italian, Polish, Russian, Chinese (Simplified, China), European Spanish, Swedish and 1 more - Released: 2013-01-16 - Data updated: 2026-07-06 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/ohms-law-and-power-law-calculator/id592763080/reviews.md ## What is Ohm's Law & Power Law Calculator? Ohm's law and the power law describe the relationship between the following four electrical entities: Entity..............Unit.......Symbols Voltage..........Volts......V Current..........Amps.....A, I Resistance...Ohms.....Ω, R Power.............Watts.....W Ohm's law: Voltage = Current x Resistance Power law: Power = Voltage x Current Set any two, and the other two can be calculated. This application allows you to continually lock one parameter and input another, enabling rapid "what-if" recalculation. Use the keypad to enter a value then tap on the parameter you want to set. It is now fixed, as shown by the padlock symbol. Enter another parameter and the remaining two are calculated. The most recently entered parameter becomes the new fixed one. You can alter which parameter is fixed by tapping it when the input box is empty, or by dragging the padlock to it. You can 'Freeze' a parameter with a long press until it changes colour. Now alter any of the other three as required. To unfreeze, with the input box empty, tap any other parameter. The value of the fixed parameter may not be changed. If you attempt to do so, the padlock will flash. In this case, fix another parameter first. Available in the following Languages: English, French, German, Swedish, Russian, Polish, Spanish, Italian, Chinese (Traditional & Simplified). * * * * * * * * * * * * * * * * * * * * * * * If you find any errors, or have any suggestions, please email us the details & we will address them! support@cressall.com ## Key features - Ohm's Law calculations - Power Law calculations - Lock and unlock parameters - Rapid "what-if" recalculations - Multi-language support - Intuitive keypad input ## Recent user reviews (10 of 71) All indexed reviews: https://appshunter.io/ios/app/ohms-law-and-power-law-calculator/id592763080/reviews.md ### 5/5 — Good App *2025-01-02, version 1.7* Helps me when working on cars, motorcycles, boats etc. ### 5/5 — Eccezionale applicazione *2024-12-28, version 1.7* E’ da più di due anni che uso Cressal e posso affermare che è utili e facilissima da usare. Complimenti allo sviluppatore. ### 5/5 — Condivido *2023-12-17, version 1.7* Condivido con tutte le alte recensioni… veramente utile. ### 5/5 — Très bien *2023-12-06, version 1.7* Applications pratiques ### 5/5 — My “Go To” *2022-03-11, version 1.7* The first app I turn to when figuring out my RV battery loads and inverter efficiency issues. Love it!!! ### 5/5 — Simple and Ad Free *2022-02-06, version 1.7* Title says it all. ### 5/5 — Мир *2021-09-07, version 1.7* Будем работать, в мире. Спасибо. ### 1/5 — Nul *2020-03-20, version 1.7* Ne fonctionne pas ### 5/5 — Good *2019-12-25, version 1.7* 小煙計算公式方便 ### 5/5 — Полезно. *2019-09-08, version 1.7* Все ОК. Нужная программа. ## Frequently asked questions about Ohm's Law & Power Law Calculator ### What does this app do? This application calculates electrical parameters based on Ohm's Law and the Power Law. You can input any two electrical entities (voltage, current, resistance, or power) and the app will automatically compute the other two. It's designed for rapid "what-if" scenario analysis in electrical calculations. ### How do I use the calculator? Use the keypad to enter a value, then tap the parameter you wish to set. This parameter will be locked, indicated by a padlock symbol. Then, enter another parameter, and the remaining two will be calculated. You can change which parameter is fixed by tapping it when the input box is empty or by dragging the padlock. ### Is this app free to use? Yes, this application is completely free to use. There are no in-app purchases or advertisements, and it does not require a subscription. ### What electrical entities can be calculated? The app calculates Voltage (Volts), Current (Amps), Resistance (Ohms), and Power (Watts). By setting any two of these, the other two can be determined using Ohm's Law (V=IR) and the Power Law (P=VI). ### What languages does the app support? The application is available in multiple languages, including English, French, German, Swedish, Russian, Polish, Spanish, Italian, and Chinese (Traditional & Simplified). ## Version history (last 5 releases) ### 1.7 — 2017-06-12 This app has been updated by Apple to display the Apple Watch app icon. Latest iOS support(64 Bit). Minor UI improvements. ### 1.6 — 2013-10-28 Update for iOS 7 styling. Demo feature - Shows how to enter, lock, and freeze parameters. ### 1.5 — 2013-06-06 Added automatic SI unit prefixes. App now handles & conveniently displays large and small values. ### 1.4 — 2013-05-30 Fixed: No recalculation after manually dragging padlock. Freezing of zero value parameter. ### 1.3 — 2013-05-16 Added enhanced parameter locking: You can now "Freeze" a parameter with a long press until it changes colour. Now alter any of the other three as required. To unfreeze, with the input box empty, tap any other parameter. Added Localisations for Spanish, Chinese (Traditional & Simplified), and Italian ## Apps similar to Ohm's Law & Power Law Calculator | App | Rating | Price | Category | | --- | --- | --- | --- | | [KH-F](https://appshunter.io/ios/app/kh-f/id1665076881) | — | Free | Utilities | | [Simple Circuit Builder](https://appshunter.io/ios/app/simple-circuit-builder/id1294616098) | 4.0 (28) | Free | Utilities | | [Ohmify - electronics tools](https://appshunter.io/ios/app/ohmify-electronics-tools/id6741767371) | 5.0 (1) | Free | Utilities | | [Thermistor Calculator](https://appshunter.io/ios/app/thermistor-calculator/id6448946358) | — | Free | Utilities | | [KG Serials](https://appshunter.io/ios/app/kg-serials/id1556594835) | 3.4 (7) | Free | Utilities | | [The Ohms Law Calculator](https://appshunter.io/ios/app/the-ohms-law-calculator/id6447774551) | — | $0.99 | Utilities | ## Related topics [ohms law](https://appshunter.io/ios/topics/ohms-law) · [ohms](https://appshunter.io/ios/topics/ohms) · [the power law calc](https://appshunter.io/ios/topics/the-power-law-calc) --- *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 2026-07-06.*