# Timer 555 Calculator > Electronics circuit calculator for monostable and astable configurations. (iPhone/iPad app by Siu Yuen Ho.) - Source: https://appshunter.io/ios/app/timer-555-calculator/id834044557 (this page in markdown: same URL + `.md`) - Developer: [Siu Yuen Ho](https://appshunter.io/developer/814088527) - Category: Utilities - Price: Free with in-app purchases - Rating: 3.90/5 from 8 App Store ratings · 4 written reviews indexed - Age rating: 4+ - Requires: iOS 13.2 · 3 MB - Languages: French (France), German (Germany), American English, Chinese (Simplified, China), Chinese (Traditional, Taiwan), Korean, European Spanish, Hindi, Italian, Japanese and 2 more - Released: 2014-03-06 - Data updated: 2026-08-28 - Monetization: free with in-app purchases - User reviews in markdown: https://appshunter.io/ios/app/timer-555-calculator/id834044557/reviews.md ## What is Timer 555 Calculator? This app is used to calculate monostable and astable circuit. Features * Calculate pulse width of monostable circuit * Calculate frequency of astable circuit * Find out combination of components making a desire pulse width in monostable circuit * Find out combination of components making a desire frequency in astable circuit * Saving component values in CSV file * Upload generated CSV files via AirDrop or iCloud Drive * Support English, German, French, Italian, Spanish, Portuguese, Japanese, Korean, Russian ## Key features - Monostable circuit pulse width calculation - Astable circuit frequency calculation - Component combination finder - Save component values to CSV - Upload CSV via AirDrop/iCloud Drive - Multi-language support ## Pricing and in-app purchases Base price: Free. **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | Unlock Pro feature | $0.99 | one-time | ## Recent user reviews (4 of 4) All indexed reviews: https://appshunter.io/ios/app/timer-555-calculator/id834044557/reviews.md ### 5/5 — Пользователь. *2018-10-09* Не смотря на простоту программы, лично мне нравиться и интерфейс и выполняемые ею функции. ### 5/5 — Good app *2018-07-26* It was a very good app and easy to use and I have used it multiple times with no issues whatsoever. ### 5/5 — Good, simple *2015-01-08* Nice little 555 timer App. Great for most common 555 applications. It would be nice if other circuits found in books like the 555 Timer Cookbook would be included too. ### 5/5 — Excellent Tool *2014-10-14* This application is easy to use and very useful ## Frequently asked questions about Timer 555 Calculator ### What can Timer 555 Calculator do? Timer 555 Calculator helps you calculate the pulse width of monostable circuits and the frequency of astable circuits. It also assists in finding component combinations for desired outputs and allows saving/uploading data. ### Is Timer 555 Calculator free to use? Yes, Timer 555 Calculator is free to download and use. It does offer in-app purchases, but the core functionality is available without cost. ### What devices does Timer 555 Calculator support? Timer 555 Calculator is available for iPhone and iPad devices. ### How often is Timer 555 Calculator updated? The latest version, 3.0.20, was updated on May 14, 2025, indicating active development and regular updates. ### What languages does Timer 555 Calculator support? Timer 555 Calculator supports English, German, French, Italian, Spanish, Portuguese, Japanese, Korean, and Russian. ### What is the age rating for Timer 555 Calculator? Timer 555 Calculator has an age rating of 4+, making it suitable for a wide range of users. ### Does Timer 555 Calculator have ads? No, Timer 555 Calculator does not contain advertisements. The app is free with optional in-app purchases. ### How does Timer 555 Calculator compare to other circuit calculators? Timer 555 Calculator focuses specifically on 555 timer circuits, offering detailed calculations for monostable and astable modes, along with component combination suggestions and data export features. ## Version history (last 5 releases) ### 3.0.20 — 2025-05-14 Fix minor bugs ### 3.0.15 — 2024-03-25 Fix minor bugs ### 3.0.10 — 2021-07-02 * Add Hindi * Fix minor bugs ### 3.0.0 — 2021-05-16 Fix minor bugs ### 2.9.5 — 2021-05-02 Fix minor bugs ## Apps similar to Timer 555 Calculator | App | Rating | Price | Category | | --- | --- | --- | --- | | [Simple Circuit Builder](https://appshunter.io/ios/app/simple-circuit-builder/id1294616098) | 4.0 (28) | Free | Utilities | | [Resistor AI Calculator](https://appshunter.io/ios/app/resistor-ai-calculator/id1587462977) | 3.6 (5) | Free | Utilities | | [555 Calc](https://appshunter.io/ios/app/555-calc/id868058244) | 4.0 (3) | Free | Utilities | | [Electronic Component Codes](https://appshunter.io/ios/app/electronic-component-codes/id1670579756) | — | Free | Utilities | | [Resistor Code Calculators](https://appshunter.io/ios/app/resistor-code-calculators/id1465336419) | — | Free | Utilities | | [Circuit Simulator Q](https://appshunter.io/ios/app/circuit-simulator-q/id6742368702) | 2.7 (3) | Free | Utilities | ## More apps by Siu Yuen Ho - [Easy Ohm's Law](https://appshunter.io/ios/app/easy-ohms-law/id814088524) - [RC Circuit Pro](https://appshunter.io/ios/app/rc-circuit-pro/id824145786) - [RC Circuit](https://appshunter.io/ios/app/rc-circuit/id824460716) - [Resistor Tools Pro](https://appshunter.io/ios/app/resistor-tools-pro/id825620924) - [Resistor Tools](https://appshunter.io/ios/app/resistor-tools/id826045228) - [Timer 555 Calculator Pro](https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125) All apps by Siu Yuen Ho: https://appshunter.io/developer/814088527 ## Related topics [timer 555 calculator](https://appshunter.io/ios/topics/timer-555-calculator) · [555 calc](https://appshunter.io/ios/topics/555-calc) · [timer 555 calculator pro](https://appshunter.io/ios/topics/timer-555-calculator-pro) · [555](https://appshunter.io/ios/topics/555) --- *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 2026-08-28.*