# Fit Tolerance ISO vs TechRef

The clearest difference is in-app purchases: Fit Tolerance ISO at none against TechRef's 1. Fit Tolerance ISO also leads on iOS requirement (15.0 vs 17.6). TechRef's advantage is ads (none vs shown) and update cadence (every 3 days vs every 12 months). On price and device support there is nothing between them.

Both are free to download. TechRef sells 1 one-off in-app purchase. Fit Tolerance ISO asks for nothing beyond the download.

Fit Tolerance ISO ships an update every 12 months, TechRef every 3 days. The most recent releases landed on October 12, 2026 and October 11, 2026 respectively.

## The numbers

| Metric | Fit Tolerance ISO | TechRef |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/fit-tolerance-iso/id1251895012/reviews)** | — |
| Number of ratings | **2** | — |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 12 months | **Every 3 days** |
| Monetization | Ad-supported | — |
| Size | 51 MB | 4 MB |
| Requires iOS | **15.0** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Yasar Yucel Yesilbag](https://appshunter.io/developer/1251895011) | [MASARU KATO](https://appshunter.io/developer/1883480774) |

## What reviewers say

### Fit Tolerance ISO

[App page](https://appshunter.io/ios/app/fit-tolerance-iso/id1251895012)

Calculates engineering tolerances for various mechanical components based on ISO and ANSI standards. It determines size limits, deviations, and fit types for holes and shafts, offering schematic representations of fits.

**Highlights:** Calculates engineering tolerances, Supports ISO and ANSI standards, Determines clearance, transition, and interference fits, Provides schematic fit representations, Includes preferred tolerances and fits, Works with metric units

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

**In-app purchases:** none


### TechRef

[App page](https://appshunter.io/ios/app/techref/id6775818457)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| TechRef Pro | $6.99 | one-time |


## Frequently asked questions

### Is Fit Tolerance ISO free?

Fit Tolerance ISO is free to download, with no in-app purchases.

### Is TechRef free?

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

### Do Fit Tolerance ISO or TechRef have ads?

Fit Tolerance ISO shows ads; TechRef does not.

### Which is updated more often, Fit Tolerance ISO or TechRef?

Fit Tolerance ISO ships an update every 12 months, and TechRef every 3 days. Most recently, Fit Tolerance ISO was updated on October 12, 2026 and TechRef on October 11, 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.*