# 555 Calc vs Otyoo Basic

The clearest difference is ads: Otyoo Basic at none against 555 Calc's shown. Otyoo Basic also leads on update cadence (every 4 months vs every 20 months) and iOS requirement (9.0 vs 11.0). On price, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

555 Calc ships an update every 20 months, Otyoo Basic every 4 months. The most recent releases landed on September 27, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | 555 Calc | Otyoo Basic |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.0 (3 ratings)](https://appshunter.io/ios/app/555-calc/id868058244/reviews)** | — |
| Number of ratings | **3** | — |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | Every 20 months | **Every 4 months** |
| Monetization | Ad-supported | — |
| Size | 18 MB | 49 MB |
| Requires iOS | 11.0 | **9.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Jibiki Works](https://appshunter.io/developer/556845808) | [OTYOO TEKNOLOJI ANONIM SIRKETI](https://appshunter.io/developer/1758722484) |

## What reviewers say

### 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


### Otyoo Basic

[App page](https://appshunter.io/ios/app/otyoo-basic/id879545980)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is 555 Calc free?

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

### Is Otyoo Basic free?

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

### Do 555 Calc or Otyoo Basic have ads?

555 Calc shows ads; Otyoo Basic does not.

### Which is updated more often, 555 Calc or Otyoo Basic?

555 Calc ships an update every 20 months, and Otyoo Basic every 4 months. Most recently, 555 Calc was updated on September 27, 2026 and Otyoo Basic on October 3, 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.*