App Does nothing
This application was just a waste of time.
it does nothing.
it does nothing.
Does its job
It is one thing and it does it really well.
Free
With Ads
About
This utility app helps engineers and hobbyists calculate resistor values for circuits using the Timer IC 555. Simply input frequency, duty ratio, and capacitor values to get the required resistor outputs.
✓Calculate resistor values
✓Input frequency
✓Input duty ratio
✓Input capacitor value
✓Timer IC 555 circuit design
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What's New in 555 Calc
1.7
January 2, 2026
* Support iPad and Mac(Apple Silicon).
User reviews
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FAQ
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.
