# SI Prefix Converter vs Electronic Circuits Calc Pro

The clearest difference is price: SI Prefix Converter at Free against Electronic Circuits Calc Pro's $4.99. SI Prefix Converter also leads on iOS requirement (8.0 vs 17.0). Electronic Circuits Calc Pro's advantage is update cadence (every 2 months vs every 9 months). On ads, in-app purchases and device support there is nothing between them.

SI Prefix Converter is free to download; Electronic Circuits Calc Pro costs $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

SI Prefix Converter ships an update every 9 months, Electronic Circuits Calc Pro every 2 months. The most recent releases landed on November 2, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | SI Prefix Converter | Electronic Circuits Calc Pro |
| --- | --- | --- |
| Price | **Free** | $4.99 |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 9 months | **Every 2 months** |
| Size | 23 MB | 19 MB |
| Requires iOS | **8.0** | 17.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Age rating | 4+ | 4+ |
| Developer | [Yuki Takeda](https://appshunter.io/developer/1021096508) | [ALG Software Lab](https://appshunter.io/developer/1650561236) |

## What reviewers say

### SI Prefix Converter

[App page](https://appshunter.io/ios/app/si-prefix-converter/id1047118885)

**Features:** Vision Pro support

**In-app purchases:** none


### Electronic Circuits Calc Pro

[App page](https://appshunter.io/ios/app/electronic-circuits-calc-pro/id1658493129)

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is SI Prefix Converter free?

SI Prefix Converter is free to download, with no in-app purchases.

### Is Electronic Circuits Calc Pro free?

Electronic Circuits Calc Pro costs $4.99, with no in-app purchases.

### Do SI Prefix Converter or Electronic Circuits Calc Pro have ads?

Neither SI Prefix Converter nor Electronic Circuits Calc Pro shows ads.

### Which is updated more often, SI Prefix Converter or Electronic Circuits Calc Pro?

SI Prefix Converter ships an update every 9 months, and Electronic Circuits Calc Pro every 2 months. Most recently, SI Prefix Converter was updated on November 2, 2026 and Electronic Circuits Calc Pro on November 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.*