# ISO Fits vs Bolt Length

The clearest difference is review sentiment: ISO Fits at 95% against Bolt Length's 33%. ISO Fits also leads on rating (4.2 vs 3.0) and ads (none vs shown). On price, in-app purchases, monetization model and device support there is nothing between them.

Both are free to download. ISO Fits sells 1 one-off in-app purchase and Bolt Length 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 3.0. Both are backed by a comparable volume of ratings — 6 and 2 respectively. Written reviews point the same way: 95% of ISO Fits's written reviews are positive against 33% of Bolt Length's.

ISO Fits ships an update every 5 months, Bolt Length every 20 months. The most recent releases landed on October 23, 2026 and November 1, 2026 respectively.

## The numbers

| Metric | ISO Fits | Bolt Length |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.2 (6 ratings)](https://appshunter.io/ios/app/iso-fits/id396863755/reviews)** | [3.0 (2 ratings)](https://appshunter.io/ios/app/bolt-length-nominal-length/id1042345193/reviews) |
| Number of ratings | **6** | 2 |
| Positive reviews | **94.6% of reviews** | 33.3% of reviews |
| In-app purchases | Yes | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 5 months** | Every 20 months |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 66 MB | 6 MB |
| Requires iOS | 15.6 | **14.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Trelleborg Sealing Solutions](https://appshunter.io/developer/396863758) | [mitsunori oishi](https://appshunter.io/developer/905649994) |

## 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 |


### Bolt Length

[App page](https://appshunter.io/ios/app/bolt-length-nominal-length/id1042345193)

This application helps calculate the length of metric coarse screws based on Japanese Industrial Standards. It is designed for mechanical design purposes and should be used at the user's own risk.

**Highlights:** Metric coarse screw length calculation, Conforms to Japanese Industrial Standards (JIS), Designed for mechanical design, User risk disclaimer

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Hide Ads | $1.99 | one-time |


## Frequently asked questions

### Is ISO Fits free?

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

### Is Bolt Length free?

Bolt Length is free to download, with in-app purchases available.

### Which has better reviews, ISO Fits or Bolt Length?

ISO Fits is rated higher. ISO Fits averages 4.2 out of 5 from 6 ratings, while Bolt Length averages 3.0 from 2 ratings.

### Do ISO Fits or Bolt Length have ads?

Bolt Length shows ads; ISO Fits does not.

### Which is updated more often, ISO Fits or Bolt Length?

ISO Fits ships an update every 5 months, and Bolt Length every 20 months. Most recently, ISO Fits was updated on October 23, 2026 and Bolt Length on November 1, 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.*