# 555 Calc

> Calculates resistor values for Timer IC 555 circuits based on input parameters. (iPhone/iPad app by Jibiki Works.)

- Source: https://appshunter.io/ios/app/555-calc/id868058244 (this page in markdown: same URL + `.md`)
- Developer: [Jibiki Works](https://appshunter.io/developer/556845808)
- Category: Utilities, Education
- Price: Free
- Rating: 4.00/5 from 3 App Store ratings · 2 written reviews indexed
- Age rating: 4+
- Requires: iOS 11.0 · 18 MB
- Languages: American English, Japanese
- Released: 2014-04-29
- Data updated: 2026-06-01
- Monetization: ad-supported
- User reviews in markdown: https://appshunter.io/ios/app/555-calc/id868058244/reviews.md

## What is 555 Calc?

This App calculates registors value, when designing the circuit using Timer IC 555.

How to
(1) Input Frequency value.
(2) Input Duty Ratio.
(3) Input C1 Value.
(4) Touch ‘Calculate’ button.
(5) Registors value will be displayed.

Note.
* Set Duty Ratio to 50 ~ 99.
* If you set Duty Ratio to 50, R1 value will be set to 0.

## Key features

- Calculate resistor values
- Input frequency
- Input duty ratio
- Input capacitor value
- Timer IC 555 circuit design

## Recent user reviews (2 of 2)

All indexed reviews: https://appshunter.io/ios/app/555-calc/id868058244/reviews.md

### 1/5 — App Does nothing

*2020-11-11*

This application was just a waste of time. 

it does nothing.

### 5/5 — Does its job

*2019-04-01*

It is one thing and it does it really well.

## Frequently asked questions about 555 Calc

### What is 555 Calc used for?

555 Calc is a utility app designed to calculate the resistor values needed when designing circuits using the Timer IC 555. It simplifies the process by taking your circuit's frequency, duty ratio, and capacitor values as input.

### How do I use 555 Calc?

To use 555 Calc, you input the desired frequency, duty ratio (between 50-99), and the value of C1. Then, tap the 'Calculate' button, and the app will display the required resistor values.

### What is the supported duty ratio range for 555 Calc?

The app specifies that the duty ratio should be set between 50% and 99%. If you set the duty ratio to 50%, the R1 value will automatically be set to 0.

### Does 555 Calc have ads?

Yes, 555 Calc contains advertisements. As it is a free application, ads are displayed to support its development and maintenance.

### What devices is 555 Calc available on?

555 Calc is available for iPhone, iPad, and iPod devices. It is designed for users within the Apple ecosystem.

### What is the age rating for 555 Calc?

555 Calc has an age rating of 4+. This indicates it is suitable for users of all ages, with no mature content.

### When was 555 Calc last updated?

The latest version of 555 Calc is 1.7, which was last updated on January 2, 2026. This suggests the app is actively maintained.

### What is the user rating for 555 Calc?

555 Calc has a rating of 4.0 stars based on 3 ratings. This indicates a generally positive reception from its user base.

## Version history (last 5 releases)

### 1.7 — 2026-01-02

* Support iPad and Mac(Apple Silicon).

### 1.6 — 2025-05-01

* Fixed problem with waveform diagrams not being visible in dark mode 
* Added titles for each section

### 1.5 — 2023-08-27

* Add the calculate button.
* Add the duty ratio graph.
* Fix formulas.

### 1.4 — 2022-11-19

Add a numerical formula on the screen.

### 1.3 — 2022-10-28

* Fix for R1 values not being displayed in dark mode.

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## More apps by Jibiki Works

- [LED Calc.](https://appshunter.io/ios/app/led-calc/id556845805)
- [No Share Camera](https://appshunter.io/ios/app/no-share-camera/id987298376)

All apps by Jibiki Works: https://appshunter.io/developer/556845808

## Related topics

[555 calc](https://appshunter.io/ios/topics/555-calc) · [jibiki works](https://appshunter.io/ios/topics/jibiki-works) · [timer 555 calculator](https://appshunter.io/ios/topics/timer-555-calculator)

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*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 2026-06-01.*