# HydroCalc Basic vs Unit Converter Engineering Pro

The clearest difference is iOS requirement: Unit Converter Engineering Pro at 13.0 against HydroCalc Basic's 15.1. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. HydroCalc Basic sells 1 one-off in-app purchase and Unit Converter Engineering Pro sells 2 in-app purchases, starting at $5.99 per 7 days. Whichever you choose, the download price is not the number that matters.

HydroCalc Basic ships an update every 11 days, Unit Converter Engineering Pro weekly. The most recent releases landed on October 4, 2026 and October 2, 2026 respectively.

## The numbers

| Metric | HydroCalc Basic | Unit Converter Engineering Pro |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/unit-converter-engineering-pro/id6757166485/reviews)** |
| Number of ratings | — | **1** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 11 days | **Weekly** |
| Monetization | — | Free with in-app purchases |
| Size | 35 MB | 77 MB |
| Requires iOS | 15.1 | **13.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Transparent Blue Water LLC](https://appshunter.io/developer/1847968351) | [Kaiguri Tech](https://appshunter.io/developer/1864995084) |

## What reviewers say

### HydroCalc Basic

[App page](https://appshunter.io/ios/app/hydrocalc-basic/id6752577110)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium - Flow Units & Ad-Free | $1.99 | one-time |


### Unit Converter Engineering Pro

[App page](https://appshunter.io/ios/app/unit-converter-engineering-pro/id6757166485)

This app provides precise unit conversions for engineers, scientists, and students. It supports over 100 units across 35 categories, including scientific notation and 9-digit decimal precision. The tool works offline and adheres to SI, NIST, and ISO standards.

**Highlights:** Over 100 units in 35+ categories, Scientific notation support, 9-digit decimal precision, SI, NIST, ISO compliant, Offline functionality, Specialized units included

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 3-Day Trial | $5.99 | per 7 days |
| Yearly Plan | $19.99 | per year |


## Frequently asked questions

### Is HydroCalc Basic free?

HydroCalc Basic is free to download, with in-app purchases available.

### Is Unit Converter Engineering Pro free?

Unit Converter Engineering Pro is free to download, with in-app purchases available.

### Do HydroCalc Basic or Unit Converter Engineering Pro have ads?

Neither HydroCalc Basic nor Unit Converter Engineering Pro shows ads.

### Which is updated more often, HydroCalc Basic or Unit Converter Engineering Pro?

HydroCalc Basic ships an update every 11 days, and Unit Converter Engineering Pro weekly. Most recently, HydroCalc Basic was updated on October 4, 2026 and Unit Converter Engineering Pro on October 2, 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.*