# Timer 555 Calculator vs 555 Calc

Timer 555 Calculator and 555 Calc both sit at 3.9 stars, but that hides the real split: 100% of Timer 555 Calculator's written reviews are positive against 50% of 555 Calc's. Timer 555 Calculator also leads on ads (none vs shown) and update cadence (every 3 months vs every 20 months). 555 Calc's advantage is in-app purchases (none vs 1) and iOS requirement (11.0 vs 13.2). On price, rating, ratings volume and device support there is nothing between them.

Both are free to download. Timer 555 Calculator sells 1 one-off in-app purchase. 555 Calc asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 3.9 for Timer 555 Calculator against 4.0 for 555 Calc. Both are backed by a comparable volume of ratings — 8 and 3 respectively. Written reviews are what separate them: 100% of Timer 555 Calculator's written reviews are positive against 50% of 555 Calc's.

Timer 555 Calculator ships an update every 3 months, 555 Calc every 20 months. The most recent releases landed on September 24, 2026 and June 1, 2026 respectively.

## The numbers

| Metric | Timer 555 Calculator | 555 Calc |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.9 (8 ratings)](https://appshunter.io/ios/app/timer-555-calculator/id834044557/reviews) | **[4.0 (3 ratings)](https://appshunter.io/ios/app/555-calc/id868058244/reviews)** |
| Number of ratings | **8** | 3 |
| Positive reviews | **100.0% of reviews** | 50.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | **Every 3 months** | Every 20 months |
| Monetization | Free with in-app purchases | **Ad-supported** |
| Size | 3 MB | 18 MB |
| Requires iOS | 13.2 | **11.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [Jibiki Works](https://appshunter.io/developer/556845808) |

## What reviewers say

### Timer 555 Calculator

[App page](https://appshunter.io/ios/app/timer-555-calculator/id834044557)

Calculate monostable and astable circuits for electronics projects. Determine pulse width and frequency, find component combinations, and save/upload data. Supports multiple languages.

**Highlights:** 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

**Features:** Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock Pro feature | $0.99 | one-time |


### 555 Calc

[App page](https://appshunter.io/ios/app/555-calc/id868058244)

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.

**Highlights:** Calculate resistor values, Input frequency, Input duty ratio, Input capacitor value, Timer IC 555 circuit design

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Timer 555 Calculator free?

Timer 555 Calculator is free to download, with in-app purchases available.

### Is 555 Calc free?

555 Calc is free to download, with no in-app purchases.

### Which has better reviews, Timer 555 Calculator or 555 Calc?

555 Calc is rated higher. Timer 555 Calculator averages 3.9 out of 5 from 8 ratings, while 555 Calc averages 4.0 from 3 ratings.

### Do Timer 555 Calculator or 555 Calc have ads?

555 Calc shows ads; Timer 555 Calculator does not.

### Which is updated more often, Timer 555 Calculator or 555 Calc?

Timer 555 Calculator ships an update every 3 months, and 555 Calc every 20 months. Most recently, Timer 555 Calculator was updated on September 24, 2026 and 555 Calc on June 1, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*