# Units Converter for Engineers vs Stacked

The clearest difference is rating: Stacked at 4.6 against Units Converter for Engineers's 3.0. Stacked also leads on review sentiment (67% vs 50%) and ratings volume (13 vs 2). Units Converter for Engineers's advantage is update cadence (every 5 weeks vs every 7 months). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Units Converter for Engineers sells 2 one-off in-app purchases and Stacked sells 3 in-app purchases, starting at $3.99 per month. Whichever you choose, the download price is not the number that matters.

Stacked holds the better App Store score, 4.6 against 3.0. That said, the two scores are not equally well evidenced: Stacked has 13 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 50% of Units Converter for Engineers's written reviews are positive against 67% of Stacked's.

Units Converter for Engineers ships an update every 5 weeks, Stacked every 7 months. The most recent releases landed on September 19, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Units Converter for Engineers | Stacked |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.0 (2 ratings)](https://appshunter.io/ios/app/units-converter-for-engineers/id1018604081/reviews) | **[4.6 (13 ratings)](https://appshunter.io/ios/app/stacked-routine-stack-habits/id6740246728/reviews)** |
| Number of ratings | 2 | **13** |
| Positive reviews | 50.0% of reviews | **66.7% of reviews** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 5 weeks** | Every 7 months |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 5 MB | 61 MB |
| Requires iOS | 16.6 | 16.6 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [Lucy Enterprises](https://appshunter.io/developer/1656612108) | [Tip Tap Apps](https://appshunter.io/developer/1257263778) |

## What reviewers say

### Units Converter for Engineers

[App page](https://appshunter.io/ios/app/units-converter-for-engineers/id1018604081)

This tool allows professionals and students to convert units and currencies using dimensional analysis. It supports a vast number of unit combinations and includes physical constants. Currency rates are updated monthly.

**Highlights:** Free-form unit conversion via dimensional analysis, Supports over 300 single units, Supports over 165 currencies with automatic updates, Includes dozens of physical constants, Identifies unit mismatches, Glossary of available units

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock all features | $0.99 | one-time |
| Remove ads | $1.99 | one-time |


### Stacked

[App page](https://appshunter.io/ios/app/stacked-routine-stack-habits/id6740246728)

Build powerful daily routines and track habits with this all-in-one task manager. Combine tasks and habits into customized routines, receive step-by-step guidance, and monitor progress. Offers free and premium features to enhance productivity and time management.

**Highlights:** Create customizable routines, Step-by-step routine guidance, Track habits and tasks together, Flexible task types (free/premium), Progress tracking and statistics, Custom notifications and reminders, Habit stacking technique integration

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Stacked Prime Monthly | $3.99 | per month |
| Stacked Prime Yearly | $17.99 | per year |
| Stacked Prime Lifetime | $39.99 | one-time |


## Frequently asked questions

### Is Units Converter for Engineers free?

Units Converter for Engineers is free to download, with in-app purchases available.

### Is Stacked free?

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

### Which has better reviews, Units Converter for Engineers or Stacked?

Stacked is rated higher. Units Converter for Engineers averages 3.0 out of 5 from 2 ratings, while Stacked averages 4.6 from 13 ratings.

### Do Units Converter for Engineers or Stacked have ads?

Neither Units Converter for Engineers nor Stacked shows ads.

### Which is updated more often, Units Converter for Engineers or Stacked?

Units Converter for Engineers ships an update every 5 weeks, and Stacked every 7 months. Most recently, Units Converter for Engineers was updated on September 19, 2026 and Stacked 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.*