# STS vs Transformer Calculator.

The clearest difference is in-app purchases: STS at none against Transformer Calculator.'s 1. STS also leads on ads (none vs shown) and rating (5.0 vs 4.8). Transformer Calculator.'s advantage is ratings volume (48 vs 1). On price, update cadence and device support there is nothing between them.

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

STS holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: Transformer Calculator. has 48 ratings behind it against 1, so its average is the more settled of the two.

STS ships an update every 5 months, Transformer Calculator. every 4 months. The most recent releases landed on October 16, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | STS | Transformer Calculator. |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/sts-soft-starter-simulation/id1409663811/reviews)** | [4.8 (48 ratings)](https://appshunter.io/ios/app/transformer-calculator/id1506155081/reviews) |
| Number of ratings | 1 | **48** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 5 months | **Every 4 months** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 67 MB | 41 MB |
| Requires iOS | **12.2** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Siemens AG](https://appshunter.io/developer/394503271) | [V PUGAZHENTHI](https://appshunter.io/developer/491898049) |

## What reviewers say

### STS

[App page](https://appshunter.io/ios/app/sts-soft-starter-simulation/id1409663811)

This utility helps users select the appropriate Siemens soft starter for their specific needs. It simulates applications based on various parameters and provides detailed reports, with direct links to product data.

**Highlights:** Soft starter application simulation, Input data for environment, motor, and load, Starting parameter configuration, Suggested soft starter selection, Simulation and component reports, Direct access to Siemens Industry Mall data

**In-app purchases:** none


### Transformer Calculator.

[App page](https://appshunter.io/ios/app/transformer-calculator/id1506155081)

This app simplifies transformer calculations for engineers and students. It accurately computes primary and secondary currents, turns ratios, and secondary voltages based on user inputs for transformer ratings and winding turns.

**Highlights:** Primary and secondary current calculations, Turns ratio determination, Transformer type identification, Secondary voltage calculation, Supports 1Φ and 3Φ phases, User-friendly interface

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Go Pro | $3.99 | one-time |


## Frequently asked questions

### Is STS free?

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

### Is Transformer Calculator. free?

Transformer Calculator. is free to download, with in-app purchases available.

### Which has better reviews, STS or Transformer Calculator.?

STS is rated higher. STS averages 5.0 out of 5 from 1 ratings, while Transformer Calculator. averages 4.8 from 48 ratings.

### Do STS or Transformer Calculator. have ads?

Transformer Calculator. shows ads; STS does not.

### Which is updated more often, STS or Transformer Calculator.?

STS ships an update every 5 months, and Transformer Calculator. every 4 months. Most recently, STS was updated on October 16, 2026 and Transformer Calculator. on October 10, 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.*