# Only One Calculator — All-in-One Calculator > All-in-one calculator with currency exchange, unit conversion, and undo/redo. (iPhone/iPad app by Jia Hua Huang.) - Source: https://appshunter.io/ios/app/only-one-calculator/id1488596497 (this page in markdown: same URL + `.md`) - Developer: [Jia Hua Huang](https://appshunter.io/developer/1488596496) - Category: Utilities, Finance - Price: Free - Rating: 5.00/5 from 2 App Store ratings · 2 written reviews indexed - Age rating: 4+ - Requires: iOS 11.0 · 34 MB - Languages: English, Chinese, Chinese - Released: 2019-11-23 - Data updated: 2026-06-03 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/only-one-calculator/id1488596497/reviews.md ## What is Only One Calculator? This calculator has instant currency exchange and unit conversion. With the "Undo" and "Redo" functions, you can go back to the previous steps and edit it. Select a specified currency exchange to be fixed to the calculator. When you input a number or expression, you can instantly know the conversion result, which is convenient for traveling and shopping. Features： • Can select a specified currency exchange and pin it to the calculator. During the input process, you can instantly know the exchange result, which is convenient for travel and shopping. • With the "Undo" and "Redo" functions, the calculator allows you to go back to the previous steps. It keeps up to 300 input steps for your review. So you don't have to worry about re-entering because of any mistakes during input. • Can choose between more than 160 currencies, and the exchange rate is updated manually or automatically per hour, day, or week. • The calculation expression and calculation result are recorded when pressing the equal button or clear button. You can insert the calculation expression or calculation result from a history record into the current calculation expression. • Can edit a very long calculation, and cursor control is very convenient and smooth. • During the input process, the calculation result will be shown instantly without pressing the equal button. • In addition to currency exchange, there are other conversion functions for length, weight, area, volume, and temperature. • If you need the Memory Buttons on traditional calculators, you can add them into the keyboard layout. ** Note: No Scientific Calculation Function. Not suitable for users who need Scientific Calulation. ** ## Key features - Instant currency exchange - Unit conversion (length, weight, area, volume, temperature) - Undo/Redo functionality - History of calculations - Customizable keyboard layout - Real-time calculation results ## Recent user reviews (2 of 2) All indexed reviews: https://appshunter.io/ios/app/only-one-calculator/id1488596497/reviews.md ### 5/5 — Very good *2020-10-12* Very good and user friendly!! ### 5/5 — Excellent app *2019-12-17* It’s very useful and helpful. I will recommend to other people. ## Frequently asked questions about Only One Calculator ### Does Only One Calculator have ads? No, Only One Calculator is ad-free, providing an uninterrupted user experience. ### What currency exchange options does Only One Calculator offer? It supports over 160 currencies, with exchange rates that can be updated manually or automatically per hour, day, or week. You can also pin a specific currency for constant access. ### How does the undo/redo feature work in Only One Calculator? The undo and redo functions allow you to revert to previous calculation steps, storing up to 300 inputs for review and editing, preventing the need to re-enter data. ### What types of unit conversions are available in Only One Calculator? In addition to currency, it offers conversions for length, weight, area, volume, and temperature. ### Can I customize the keyboard in Only One Calculator? Yes, you can add memory buttons to the keyboard layout, similar to traditional calculators, to suit your input preferences. ### Is Only One Calculator suitable for scientific calculations? No, Only One Calculator does not have scientific calculation functions and is not suitable for users requiring that capability. ### How often is Only One Calculator updated? The app was last updated on June 3, 2023, with version 1.7. This indicates a relatively recent update, suggesting ongoing support. ### What devices is Only One Calculator available on? Only One Calculator is available for iPhone and iPod devices. ## Version history (last 5 releases) ### 1.7 — 2023-06-03 Minor bug fixes ### 1.6 — 2020-06-26 Minor bug fixes ### 1.5 — 2020-01-13 Minor bug fixes ### 1.4 — 2019-12-21 Minor bug fixes ### 1.3 — 2019-12-10 Minor bug fixes ## Apps similar to Only One Calculator | App | Rating | Price | Category | | --- | --- | --- | --- | | [GM calc-super calculator](https://appshunter.io/ios/app/gm-calc-super-calculator/id1450517411) | — | Free | Utilities | | [Modern Calculator - All-in-One](https://appshunter.io/ios/app/modern-calculator-all-in-one/id6478195210) | — | Free | Utilities | | [Solves: Calculator for All](https://appshunter.io/ios/app/solves-calculator-for-all/id1394359548) | 4.8 (371) | Free | Utilities | | [All Units Convertor](https://appshunter.io/ios/app/all-units-convertor/id1611287048) | 5.0 (1) | Free | Utilities | | [Calculator - Currency - Unit](https://appshunter.io/ios/app/calculator-currency-unit/id1583572133) | 5.0 (4) | Free | Utilities | | [Multi Calculator](https://appshunter.io/ios/app/multi-calculator/id6477789604) | — | Free | Utilities | ## More apps by Jia Hua Huang - [Level with voice](https://appshunter.io/ios/app/level-with-voice/id1488703366) - [港鐵到站時間 - MTR Arrival Time](https://appshunter.io/ios/app/mtr-arrival-time/id1581998240) All apps by Jia Hua Huang: https://appshunter.io/developer/1488596496 ## Related topics [only one calculator](https://appshunter.io/ios/topics/only-one-calculator) --- *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 2026-06-03.*