# ISO Fits vs Thread Calculator

ISO Fits and Thread Calculator both sit at 4.2 stars, but that hides the real split: 95% of ISO Fits's written reviews are positive against 33% of Thread Calculator's. ISO Fits also leads on ads (none vs shown) and update cadence (every 5 months vs every 18 months). Thread Calculator's advantage is in-app purchases (none vs 1). On price, rating, ratings volume and device support there is nothing between them.

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

On the App Store both sit at effectively the same score — 4.2 for ISO Fits against 4.3 for Thread Calculator. Both are backed by a comparable volume of ratings — 6 and 13 respectively. Written reviews are what separate them: 95% of ISO Fits's written reviews are positive against 33% of Thread Calculator's.

ISO Fits ships an update every 5 months, Thread Calculator every 18 months. The most recent releases landed on September 12, 2026 and September 9, 2026 respectively.

## The numbers

| Metric | ISO Fits | Thread Calculator |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.2 (6 ratings)](https://appshunter.io/ios/app/iso-fits/id396863755/reviews) | **[4.3 (13 ratings)](https://appshunter.io/ios/app/thread-calculator/id1559560290/reviews)** |
| Number of ratings | 6 | **13** |
| Positive reviews | **94.6% of reviews** | 33.3% of reviews |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | **Every 5 months** | Every 18 months |
| Monetization | Free with in-app purchases | **Ad-supported** |
| Size | 66 MB | 25 MB |
| Requires iOS | 15.6 | **15.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Trelleborg Sealing Solutions](https://appshunter.io/developer/396863758) | [GSR Gustav Stursberg GmbH](https://appshunter.io/developer/1559560292) |

## 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 |


### Thread Calculator

[App page](https://appshunter.io/ios/app/thread-calculator/id1559560290)

This app provides a quick and easy way to calculate thread dimensions for various units, including tap hole sizes and bolt specifications. It helps metalworkers find precise measurements for internal and external threads without consulting tables.

**Highlights:** Thread cutting calculator for multiple units, Cold forming calculator, Thread repair calculator, Tap hole and bolt diameter calculation, Saves time compared to tables

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is ISO Fits free?

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

### Is Thread Calculator free?

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

### Which has better reviews, ISO Fits or Thread Calculator?

Thread Calculator is rated higher. ISO Fits averages 4.2 out of 5 from 6 ratings, while Thread Calculator averages 4.3 from 13 ratings.

### Do ISO Fits or Thread Calculator have ads?

Thread Calculator shows ads; ISO Fits does not.

### Which is updated more often, ISO Fits or Thread Calculator?

ISO Fits ships an update every 5 months, and Thread Calculator every 18 months. Most recently, ISO Fits was updated on September 12, 2026 and Thread Calculator on September 9, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*