# Surface Area Calculator + Cost vs Smart Purifier

The clearest difference is rating: Surface Area Calculator + Cost at 3.5 against Smart Purifier's 1.0. Surface Area Calculator + Cost also leads on review sentiment (22% vs 0%) and ratings volume (24 vs 2). Smart Purifier's advantage is in-app purchases (none vs 3) and update cadence (fortnightly vs every 6 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. Smart Purifier asks for nothing beyond the download.

Surface Area Calculator + Cost holds the better App Store score, 3.5 against 1.0. That said, the two scores are not equally well evidenced: Surface Area Calculator + Cost has 24 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 22% of Surface Area Calculator + Cost's written reviews are positive against 0% of Smart Purifier's.

Surface Area Calculator + Cost ships an update every 6 months, Smart Purifier fortnightly. The most recent releases landed on October 1, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Surface Area Calculator + Cost | Smart Purifier |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.5 (24 ratings)](https://appshunter.io/ios/app/surface-area-calculator-plus-cost/id1502218219/reviews)** | [1.0 (2 ratings)](https://appshunter.io/ios/app/smart-purifier/id1535735160/reviews) |
| Number of ratings | **24** | 2 |
| Positive reviews | **22.2% of reviews** | 0.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 6 months | **Fortnightly** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 4 MB | 115 MB |
| Requires iOS | 15.0 | **11.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Phan Nhat Đang](https://appshunter.io/developer/1437390098) | [VIETTEL GROUP](https://appshunter.io/developer/1529233160) |

## What reviewers say

### 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 |


### Smart Purifier

[App page](https://appshunter.io/ios/app/smart-purifier/id1535735160)

Monitor and control your Smart Purifier air quality device. View real-time air quality data and adjust settings remotely. Ensure a healthy living environment with this connected appliance management tool.

**Highlights:** Remote device control, Real-time air quality monitoring, Device settings adjustment, Air purification management, Connected appliance integration

**In-app purchases:** none


## Frequently asked questions

### Is Surface Area Calculator + Cost free?

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

### Is Smart Purifier free?

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

### Which has better reviews, Surface Area Calculator + Cost or Smart Purifier?

Surface Area Calculator + Cost is rated higher. Surface Area Calculator + Cost averages 3.5 out of 5 from 24 ratings, while Smart Purifier averages 1.0 from 2 ratings.

### Do Surface Area Calculator + Cost or Smart Purifier have ads?

Neither Surface Area Calculator + Cost nor Smart Purifier shows ads.

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

Surface Area Calculator + Cost ships an update every 6 months, and Smart Purifier fortnightly. Most recently, Surface Area Calculator + Cost was updated on October 1, 2026 and Smart Purifier on October 24, 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.*