# Phase Calc vs SI Prefix Converter

The clearest difference is price: SI Prefix Converter at Free against Phase Calc's $1.99. SI Prefix Converter also leads on iOS requirement (8.0 vs 17.0). Phase Calc's advantage is update cadence (every 6 weeks vs every 9 months). On ads, in-app purchases and device support there is nothing between them.

SI Prefix Converter is free to download; Phase Calc costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Phase Calc ships an update every 6 weeks, SI Prefix Converter every 9 months. The most recent releases landed on October 23, 2026 and October 13, 2026 respectively.

## The numbers

| Metric | Phase Calc | SI Prefix Converter |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Rating | **[5.0 (4 ratings)](https://appshunter.io/ios/app/phase-calc/id837266300/reviews)** | — |
| Number of ratings | **4** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 6 weeks** | Every 9 months |
| Monetization | Paid | — |
| Size | 13 MB | 23 MB |
| Requires iOS | 17.0 | **8.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Donnie Herman](https://appshunter.io/developer/837266303) | [Yuki Takeda](https://appshunter.io/developer/1021096508) |

## What reviewers say

### Phase Calc

[App page](https://appshunter.io/ios/app/phase-calc/id837266300)

This advanced engineering app performs complex electrical calculations for three-phase power systems. It offers tools for students, technicians, and engineers to analyze unbalanced systems, perform sequence transformations, and access reference libraries. Results can be easily exported for documentation and sharing.

**Highlights:** Symmetrical component analysis, Three-phase power system calculations, Phase-to-sequence and sequence-to-phase transformations, Polar and rectangular input support, Specialized calculators and reference libraries, Exportable results for documentation

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

**In-app purchases:** none


### SI Prefix Converter

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

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Phase Calc free?

Phase Calc costs $1.99, with no in-app purchases.

### Is SI Prefix Converter free?

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

### Do Phase Calc or SI Prefix Converter have ads?

Neither Phase Calc nor SI Prefix Converter shows ads.

### Which is updated more often, Phase Calc or SI Prefix Converter?

Phase Calc ships an update every 6 weeks, and SI Prefix Converter every 9 months. Most recently, Phase Calc was updated on October 23, 2026 and SI Prefix Converter on October 13, 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.*