# Timer 555 Calculator vs Resistor

The clearest difference is rating: Resistor at 4.9 against Timer 555 Calculator's 3.9. Resistor also leads on in-app purchases (none vs 1). Timer 555 Calculator's advantage is update cadence (every 3 months vs every 9 months) and iOS requirement (13.2 vs 26.0). On price, ratings volume, ads and device support there is nothing between them.

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

Resistor holds the better App Store score, 4.9 against 3.9. Both are backed by a comparable volume of ratings — 8 and 19 respectively.

Timer 555 Calculator ships an update every 3 months, Resistor every 9 months. The most recent releases landed on October 21, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Timer 555 Calculator | Resistor |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.9 (8 ratings)](https://appshunter.io/ios/app/timer-555-calculator/id834044557/reviews) | **[4.9 (19 ratings)](https://appshunter.io/ios/app/resistor-converter/id6446839759/reviews)** |
| Number of ratings | 8 | **19** |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 3 months** | Every 9 months |
| Monetization | Free with in-app purchases | **Free** |
| Size | 3 MB | 8 MB |
| Requires iOS | **13.2** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [Gerhard Lentschik](https://appshunter.io/developer/629988041) |

## 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

[App page](https://appshunter.io/ios/app/resistor-converter/id6446839759)

Quickly calculate resistor values from color bands or SMD codes, and vice versa. This tool is ideal for electronics enthusiasts, students, and DIYers working with 4, 5, or 6-band resistors and various SMD codes. It functions offline and requires no registration.

**Highlights:** Calculate resistor values from color bands, Convert resistor values to color bands, Supports 4, 5, and 6-band resistors, Handles SMD codes (EIA-3, EIA-4, EIA-96), Works offline, No registration required

**Features:** macOS Compatibility, Vision Pro support

**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 free?

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

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

Resistor is rated higher. Timer 555 Calculator averages 3.9 out of 5 from 8 ratings, while Resistor averages 4.9 from 19 ratings.

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

Neither Timer 555 Calculator nor Resistor shows ads.

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

Timer 555 Calculator ships an update every 3 months, and Resistor every 9 months. Most recently, Timer 555 Calculator was updated on October 21, 2026 and Resistor on October 24, 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.*