# Four To Twenty: mA/V Converter — 4-20mA Process Signal Scaling > Converts 4-20mA electrical signals to process signals with custom scaling. (iPhone/iPad app by Jon Giambattista.) - Source: https://appshunter.io/ios/app/four-to-twenty-mav-converter/id1302909664 (this page in markdown: same URL + `.md`) - Developer: [Jon Giambattista](https://appshunter.io/developer/983771622) - Category: Utilities, Productivity - Price: $0.99 - Rating: 4.50/5 from 10 App Store ratings · 10 written reviews indexed - Age rating: 4+ - Requires: iOS 10.2 · 14 MB - Languages: American English - Released: 2017-10-30 - Data updated: 2026-08-25 - Monetization: paid - User reviews in markdown: https://appshunter.io/ios/app/four-to-twenty-mav-converter/id1302909664/reviews.md ## What is Four To Twenty? A simple calculator for converting electrical signals, typically 4-20mA scaled to an appropriate process signal (ex: 0-1000 psi). Choose from a wide variety of preset signal inputs and process signal outputs or enter your own custom values. Choose from 8 different themes. ## Key features - 4-20mA signal conversion - Process signal scaling - Preset signal inputs - Custom input/output values - Multiple theme options ## Recent user reviews (10 of 10) All indexed reviews: https://appshunter.io/ios/app/four-to-twenty-mav-converter/id1302909664/reviews.md ### 5/5 — Very useful *2025-04-02* App is very useful but seems to be forgotten about as far new features being added. As another review stated a percentage would be super useful and to be able to rename the custom selection too. ### 3/5 — Decent app but lacking functionality. *2024-04-23* This app is cool but I’m a little confused what the point of the changeable units is. Seems like a “feature” for the sake of having one. A feature that is needed is the ability to compute values outside of the set range. For example, converting a 3.5mA value to counts on a 4-20mA scale. A lot of troubleshooting involves out of range values. ### 5/5 — Great App! *2022-11-12* This app is fantastic! Wonder what your thoughts are on adding what the 0-100% value would be. Ex: 0-100•c 16mA would be 75%. This example is very easy but say we’re looking for 42% of the range. Hope this makes sense. ### 4/5 — Sehr nützlich, *2022-10-18* eine Erweiterung auf 3 Bereiche wäre noch besser. Auch farbige Schieberegler statt einfache Balkenanzeigen wären toll. ### 5/5 — Works well *2021-04-16* Quick and easy. It considers all the process variables units. Looks hot. Makes my job so much quicker. Rad. **Developer response:** Thanks for the review! ### 4/5 — Simple and easy *2020-12-28* I think it would be helpful if you added the math formula with it. **Developer response:** Will look at adding the formula in the next update. Thanks for the feedback ### 2/5 — Doesn’t support negative numbers *2019-05-24* Doesn’t support negative numbers for differential measurement **Developer response:** Thanks for your review. An update will be coming shortly to fix this ### 2/5 — Ausbaufähig *2019-05-20* Bei der Eingabe der Werte wird nur ein Komma angezeigt, die App verarbeitet aber nur einen Punkt. Mit Umweg kann man dann seine Werte eingeben. ### 3/5 — Decent product, needs a little work *2018-10-31* Works good as a signal calculator, but need to be able to use negative values for process variables, especially on temperature. **Developer response:** Thanks for the feedback. I'll try to push an update soon that addresses this. ### 5/5 — Works for work *2017-12-07* Simple and non cluttered interface makes it easy to use. Great for old school analog devices that are adjusted by a POT. Especially if adjustments have to be made with the transmitter in operation and you need to avoid going to minimum or maximum values. Not necessary but would like to see m3 for level as a units option. **Developer response:** Thanks for the feedback. I'll add m3/level units in the next version. ## Frequently asked questions about Four To Twenty ### What is Four To Twenty: mA/V Converter used for? Four To Twenty: mA/V Converter is a utility app designed to convert electrical signals, typically 4-20mA, into an appropriate process signal. This is useful for scaling measurements like pressure or temperature. ### Can I use custom values in Four To Twenty: mA/V Converter? Yes, in addition to a variety of preset signal inputs and process signal outputs, you can enter your own custom values for precise scaling. ### What devices does Four To Twenty: mA/V Converter support? Four To Twenty: mA/V Converter is supported on iPhone and iPod devices. ### How often is Four To Twenty: mA/V Converter updated? The latest version, 2.0, was released on October 9, 2020. Previous updates indicate a history of maintenance and feature additions. ### What is the age rating for Four To Twenty: mA/V Converter? Four To Twenty: mA/V Converter has an age rating of 4+, making it suitable for a wide range of users. ### Does Four To Twenty: mA/V Converter have ads? No, Four To Twenty: mA/V Converter does not contain advertisements, providing an uninterrupted user experience. ### What is the price of Four To Twenty: mA/V Converter? Four To Twenty: mA/V Converter is available for a one-time purchase of $0.99. ### What is the user sentiment for Four To Twenty: mA/V Converter? Users have rated Four To Twenty: mA/V Converter highly, with an average of 4.5 stars from 10 ratings, indicating positive user satisfaction. ## Version history (last 2 releases) ### 2.0 — 2020-10-09 Added support for negative numbers. Choose from 8 different themes. Fixed an issue with comma decimal point calculations. ### 1.0 — 2017-10-30 No release notes. ## More apps by Jon Giambattista - [IIFYM Macro/Calorie Calculator](https://appshunter.io/ios/app/iifym-macrocalorie-calculator/id983771623) - [Burn - Track your Exercise](https://appshunter.io/ios/app/burn-track-your-exercise/id1017151625) - [CORAL: Prostate Cancer Risk and Survival](https://appshunter.io/ios/app/coral-prostate-cancer-risk-and-survival/id1137504631) - [EQD2 Calculator](https://appshunter.io/ios/app/eqd2-calculator/id1200344433) - [Worth - Hourly Wage Timer](https://appshunter.io/ios/app/worth-hourly-wage-timer/id1202689419) - [CORAL Gyne Nomogram Calculator](https://appshunter.io/ios/app/coral-gyne-nomogram-calculator/id1212183345) All apps by Jon Giambattista: https://appshunter.io/developer/983771622 --- *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 2026-08-25.*