# Duct vs UnitConverter byNSDev

The clearest difference is review sentiment: Duct at 100% against UnitConverter byNSDev's 20%. Duct also leads on iOS requirement (11.4 vs 15.6). UnitConverter byNSDev's advantage is update cadence (every 5 months vs every 16 months). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Duct ships an update every 16 months, UnitConverter byNSDev every 5 months. The most recent releases landed on October 6, 2026 and October 4, 2026 respectively.

## The numbers

| Metric | Duct | UnitConverter byNSDev |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | **100.0% of reviews** | 20.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 16 months | **Every 5 months** |
| Monetization | Free | Free |
| Size | 3 MB | 4 MB |
| Requires iOS | **11.4** | 15.6 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Izumi Consulting,Inc.](https://appshunter.io/developer/735908925) | [NIHON SYSTEM DEVELOPER CORPORATION](https://appshunter.io/developer/1198103734) |

## What reviewers say

### Duct

[App page](https://appshunter.io/ios/app/duct-fit/id735908922)

This application simplifies the selection of duct sizes using intuitive design and simple operations. It calculates appropriate duct sizes based on airflow, standard static pressure, and air velocity, supporting both rectangular and round ducts.

**Highlights:** Intuitive design for easy duct size selection, Calculates duct size based on airflow, static pressure, and velocity, Supports both rectangular and round ducts, Visual representation of selected duct shapes, Customizable warning and upper limits for aspect ratio and air velocity, Set default standard static pressure

**Features:** macOS Compatibility

**In-app purchases:** none


### UnitConverter byNSDev

[App page](https://appshunter.io/ios/app/unitconverter-bynsdev/id1229121492)

This tool converts between 26 different types of units, displaying conversion rates and allowing you to specify decimal places. It supports a vast array of units across categories like length, mass, volume, and more.

**Highlights:** Converts 26 types of units, Displays conversion rates, Customizable decimal places, Supports numerous units in various categories, User-submitted unit requests

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

**In-app purchases:** none


## Frequently asked questions

### Is Duct free?

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

### Is UnitConverter byNSDev free?

UnitConverter byNSDev is free to download, with no in-app purchases.

### Do Duct or UnitConverter byNSDev have ads?

Neither Duct nor UnitConverter byNSDev shows ads.

### Which is updated more often, Duct or UnitConverter byNSDev?

Duct ships an update every 16 months, and UnitConverter byNSDev every 5 months. Most recently, Duct was updated on October 6, 2026 and UnitConverter byNSDev on October 4, 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.*