# Timer 555 Calculator vs Resistor Code Calculators

The clearest difference is in-app purchases: Resistor Code Calculators at none against Timer 555 Calculator's 1. Timer 555 Calculator's advantage is ads (none vs shown) and update cadence (every 3 months vs every 7 months). On price, device support and iOS requirement there is nothing between them.

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

Timer 555 Calculator ships an update every 3 months, Resistor Code Calculators every 7 months. The most recent releases landed on September 24, 2026 and September 17, 2026 respectively.

## The numbers

| Metric | Timer 555 Calculator | Resistor Code Calculators |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.9 (8 ratings)](https://appshunter.io/ios/app/timer-555-calculator/id834044557/reviews)** | — |
| Number of ratings | **8** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | **Every 3 months** | Every 7 months |
| Monetization | Free with in-app purchases | — |
| Size | 3 MB | 6 MB |
| Requires iOS | **13.2** | 13.4 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [Kanta Kikubo](https://appshunter.io/developer/1450598215) |

## 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 |


### Resistor Code Calculators

[App page](https://appshunter.io/ios/app/resistor-code-calculators/id1465336419)

**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 Resistor Code Calculators free?

Resistor Code Calculators is free to download, with no in-app purchases.

### Do Timer 555 Calculator or Resistor Code Calculators have ads?

Resistor Code Calculators shows ads; Timer 555 Calculator does not.

### Which is updated more often, Timer 555 Calculator or Resistor Code Calculators?

Timer 555 Calculator ships an update every 3 months, and Resistor Code Calculators every 7 months. Most recently, Timer 555 Calculator was updated on September 24, 2026 and Resistor Code Calculators on September 17, 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.*