# ISO Fits vs Hydraulic Engineer

The clearest difference is review sentiment: ISO Fits at 95% against Hydraulic Engineer's 25%. ISO Fits also leads on price (Free vs $4.99) and rating (4.2 vs 4.0). On update cadence, ads, in-app purchases and device support there is nothing between them.

ISO Fits is free to download; Hydraulic Engineer costs $4.99 up front. ISO Fits sells 1 one-off in-app purchase and Hydraulic Engineer sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

ISO Fits holds the better App Store score, 4.2 against 4.0. That said, the two scores are not equally well evidenced: ISO Fits has 6 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 95% of ISO Fits's written reviews are positive against 25% of Hydraulic Engineer's.

ISO Fits ships an update every 5 months, Hydraulic Engineer every 6 months. The most recent releases landed on September 12, 2026 and September 26, 2026 respectively.

## The numbers

| Metric | ISO Fits | Hydraulic Engineer |
| --- | --- | --- |
| Price | **Free** | $4.99 |
| Rating | **[4.2 (6 ratings)](https://appshunter.io/ios/app/iso-fits/id396863755/reviews)** | [4.0 (1 ratings)](https://appshunter.io/ios/app/hydraulic-engineer/id410465591/reviews) |
| Number of ratings | **6** | 1 |
| Positive reviews | **94.6% of reviews** | 25.0% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 5 months** | Every 6 months |
| Monetization | **Free with in-app purchases** | Paid |
| Size | 66 MB | 19 MB |
| Requires iOS | **15.6** | 18.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Trelleborg Sealing Solutions](https://appshunter.io/developer/396863758) | [Historycentral.com](https://appshunter.io/developer/1744330560) |

## What reviewers say

### ISO Fits

[App page](https://appshunter.io/ios/app/iso-fits/id396863755)

Calculate ISO fits and tolerances for shafts and bores. Supports metric and inch units, displays detailed fit definitions, and includes visual charts and educational videos.

**Highlights:** ISO fits calculation, Tolerance class display, Metric/inch unit switching, Tolerance charts, Updated YouTube videos

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full Version with complete ISO286 Standard | $1.99 | one-time |


### Hydraulic Engineer

[App page](https://appshunter.io/ios/app/hydraulic-engineer/id410465591)

This comprehensive calculator app offers over 1,000 hydraulic engineering formulas across 13 categories. It includes temperature conversions, reference tables, and the ability to save and share calculations. Works offline and supports both US Customary and SI Metric units.

**Highlights:** Over 1,000 hydraulic formulas, 13 specialized calculator categories, Temperature scale converters, Professional reference tables, Save and share calculations, Works offline, US Customary and SI Metric units

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

**In-app purchases (1)**

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


## Frequently asked questions

### Is ISO Fits free?

ISO Fits is free to download, with in-app purchases available.

### Is Hydraulic Engineer free?

Hydraulic Engineer costs $4.99, and also offers in-app purchases.

### Which has better reviews, ISO Fits or Hydraulic Engineer?

ISO Fits is rated higher. ISO Fits averages 4.2 out of 5 from 6 ratings, while Hydraulic Engineer averages 4.0 from 1 ratings.

### Do ISO Fits or Hydraulic Engineer have ads?

Neither ISO Fits nor Hydraulic Engineer shows ads.

### Which is updated more often, ISO Fits or Hydraulic Engineer?

ISO Fits ships an update every 5 months, and Hydraulic Engineer every 6 months. Most recently, ISO Fits was updated on September 12, 2026 and Hydraulic Engineer on September 26, 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.*