# Two vs Duct Calculator

The clearest difference is update cadence: Two at every 2 days against Duct Calculator's fortnightly. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Two sells 2 in-app purchases, starting at $0.99 per month and Duct Calculator sells 1 in-app purchase, starting at $9.99 per year. Whichever you choose, the download price is not the number that matters.

Two ships an update every 2 days, Duct Calculator fortnightly. The most recent releases landed on October 28, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | Two | Duct Calculator |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 2 days** | Fortnightly |
| Size | 4 MB | 8 MB |
| Requires iOS | 18.5 | **17.0** |
| Devices | iPhone | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Takahiro Ando](https://appshunter.io/developer/385463609) | [Vladimir Lukashov](https://appshunter.io/developer/6783697231) |

## What reviewers say

### Two

[App page](https://appshunter.io/ios/app/two-steps/id6751428715)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium Access - Monthly | $0.99 | per month |
| Premium Access - Yearly | $6.99 | per year |


### Duct Calculator

[App page](https://appshunter.io/ios/app/duct-calculator-hvac-sizing/id6789039757)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Ductulator Pro | $9.99 | per year |


## Frequently asked questions

### Is Two free?

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

### Is Duct Calculator free?

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

### Do Two or Duct Calculator have ads?

Neither Two nor Duct Calculator shows ads.

### Which is updated more often, Two or Duct Calculator?

Two ships an update every 2 days, and Duct Calculator fortnightly. Most recently, Two was updated on October 28, 2026 and Duct Calculator on October 20, 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.*