# Ruler vs Ductulator

The clearest difference is price: Ruler at Free against Ductulator's $3.99. Ruler also leads on review sentiment (63% vs 50%) and iOS requirement (15.0 vs 18.6). Ductulator's advantage is rating (4.7 vs 3.7) and in-app purchases (none vs 1). On device support there is nothing between them.

Ruler is free to download; Ductulator costs $3.99 up front. Ruler sells 1 one-off in-app purchase. Ductulator asks for nothing beyond the download.

Ductulator holds the better App Store score, 4.7 against 3.7. That said, the two scores are not equally well evidenced: Ductulator has 353 ratings behind it against 3, so its average is the more settled of the two. Written reviews complicate that: 63% of Ruler's written reviews are positive against 50% of Ductulator's, so the app with the better star average is not the one people write more warmly about.

Ruler ships an update every 5 months, Ductulator every 2 months. The most recent releases landed on October 21, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | Ruler | Ductulator |
| --- | --- | --- |
| Price | **Free** | $3.99 |
| Rating | [3.7 (3 ratings)](https://appshunter.io/ios/app/ruler-scale-ruler/id919130707/reviews) | **[4.7 (353 ratings)](https://appshunter.io/ios/app/ductulator-duct-sizing/id1474939475/reviews)** |
| Number of ratings | 3 | **353** |
| Positive reviews | **63.0% of reviews** | 50.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Every 5 months | **Every 2 months** |
| Monetization | Free with in-app purchases | **Free** |
| Best chart rank | — | **#121** |
| Size | 4 MB | 1 MB |
| Requires iOS | **15.0** | 18.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [mitsunori oishi](https://appshunter.io/developer/905649994) | [Wassim Murr](https://appshunter.io/developer/1474939474) |

## What reviewers say

### Ruler

[App page](https://appshunter.io/ios/app/ruler-scale-ruler/id919130707)

This app displays various measurement scales for length, including meters and inches. It allows users to set magnification ratios and reduced scales for different applications. Users can calibrate the ruler and adjust PPI settings for accurate measurements.

**Highlights:** Display various measurement scales, Set magnification ratios, Set reduced scales, Measure in meters and inches, Free mode for custom scales, Calibration for accuracy, PPI setting

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Hide Ads | $0.99 | one-time |


### Ductulator

[App page](https://appshunter.io/ios/app/ductulator-duct-sizing/id1474939475)

**Currently charting:** #121 Top Paid · Productivity (US App Store)

Instantly calculate HVAC duct sizes based on airflow, friction rate, or velocity. This tool provides accurate duct dimensions in seconds without needing charts, supporting various duct types and units.

**Highlights:** Instant duct sizing, Friction rate or velocity calculation, Multiple valid duct dimensions, IP and SI units support, Detailed sizing mode, Rectangular, circular, and flexible ducts

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

**In-app purchases:** none

**What reviewers like**

- 👍 Very helpful for duct sizing
- 👍 Easy to use in the field
- 👍 Saves time
- 👍 Seamless imperial/metric transitions
- 👍 Excellent tool for duct design

**What reviewers complain about**

- 👎 App should be free
- 👎 Functionality is pointless for some needs
- 👎 Doesn't help with traditional residential HVAC duct sizing
- 👎 App is a scam
- 👎 Decimal point doesn't work

**Reported bugs**

- Decimal point doesn't work on calculator
- New flex option isn't working properly
- Friction rate can't be changed in the latest version
- Skips duct sizes (e.g., 24-26)

**Requested features**

- Ability to pick duct size and see CFM
- Include flat oval ducts
- Option to select round or square duct
- Ability to enter duct size and get CFM
- Option for flex duct


## Frequently asked questions

### Is Ruler free?

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

### Is Ductulator free?

Ductulator costs $3.99, with no in-app purchases.

### Which has better reviews, Ruler or Ductulator?

Ductulator is rated higher. Ruler averages 3.7 out of 5 from 3 ratings, while Ductulator averages 4.7 from 353 ratings.

### Do Ruler or Ductulator have ads?

Ruler shows ads; Ductulator does not.

### Which is updated more often, Ruler or Ductulator?

Ruler ships an update every 5 months, and Ductulator every 2 months. Most recently, Ruler was updated on October 21, 2026 and Ductulator on October 25, 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.*