# Duct vs Surface Area Calculator + Cost

The clearest difference is review sentiment: Duct at 100% against Surface Area Calculator + Cost's 22%. Duct also leads on in-app purchases (none vs 3) and iOS requirement (11.4 vs 15.0). Surface Area Calculator + Cost's advantage is update cadence (every 6 months vs every 16 months). On price, ads and device support there is nothing between them.

Both are free to download. Surface Area Calculator + Cost sells 3 in-app purchases, starting at $1.99 per month. Duct asks for nothing beyond the download.

Duct ships an update every 16 months, Surface Area Calculator + Cost every 6 months. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | Duct | Surface Area Calculator + Cost |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[3.5 (24 ratings)](https://appshunter.io/ios/app/surface-area-calculator-plus-cost/id1502218219/reviews)** |
| Number of ratings | — | **24** |
| Positive reviews | **100.0% of reviews** | 22.2% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 16 months | **Every 6 months** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 3 MB | 4 MB |
| Requires iOS | **11.4** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Izumi Consulting,Inc.](https://appshunter.io/developer/735908925) | [Phan Nhat Đang](https://appshunter.io/developer/1437390098) |

## 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


### Surface Area Calculator + Cost

[App page](https://appshunter.io/ios/app/surface-area-calculator-plus-cost/id1502218219)

Calculate the surface area of various 3D geometric shapes and get an estimated cost for materials. Supports multiple units for calculations and results.

**Highlights:** Surface area calculation for 11 shapes, Material cost estimation, Multiple unit support, Results in various units, Subscription for unlimited access

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium monthly package | $1.99 | per month |
| Annual Premium Package | $14.99 | per year |
| Remove ads | $19.99 | one-time |


## Frequently asked questions

### Is Duct free?

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

### Is Surface Area Calculator + Cost free?

Surface Area Calculator + Cost is free to download, with in-app purchases available.

### Do Duct or Surface Area Calculator + Cost have ads?

Neither Duct nor Surface Area Calculator + Cost shows ads.

### Which is updated more often, Duct or Surface Area Calculator + Cost?

Duct ships an update every 16 months, and Surface Area Calculator + Cost every 6 months. Most recently, Duct was updated on November 1, 2026 and Surface Area Calculator + Cost on November 3, 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.*