# Ductulator vs Inservice

The clearest difference is price: Inservice at Free against Ductulator's $3.99. Inservice also leads on update cadence (fortnightly vs every 2 months) and iOS requirement (15.1 vs 18.6). Ductulator's advantage is chart position (#29 vs unranked). On ads, in-app purchases and device support there is nothing between them.

Inservice is free to download; Ductulator costs $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Ductulator ships an update every 2 months, Inservice fortnightly. The most recent releases landed on October 26, 2026 and October 13, 2026 respectively.

## The numbers

| Metric | Ductulator | Inservice |
| --- | --- | --- |
| Price | $3.99 | **Free** |
| Rating | **[4.7 (353 ratings)](https://appshunter.io/ios/app/ductulator-duct-sizing/id1474939475/reviews)** | — |
| Number of ratings | **353** | — |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Fortnightly** |
| Monetization | Free | — |
| Best chart rank | **#29** | — |
| Size | 1 MB | 30 MB |
| Requires iOS | 18.6 | **15.1** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Wassim Murr](https://appshunter.io/developer/1474939474) | [Inservice LLC](https://appshunter.io/developer/1789098034) |

## What reviewers say

### Ductulator

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

**Currently charting:** #29 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


### Inservice

[App page](https://appshunter.io/ios/app/inservice-app/id6751058712)

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

**In-app purchases:** none


## Frequently asked questions

### Is Ductulator free?

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

### Is Inservice free?

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

### Do Ductulator or Inservice have ads?

Neither Ductulator nor Inservice shows ads.

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

Ductulator ships an update every 2 months, and Inservice fortnightly. Most recently, Ductulator was updated on October 26, 2026 and Inservice on October 13, 2026.

---

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