# Gravity! vs Stars Units Sizes Objects

The clearest difference is in-app purchases: Stars Units Sizes Objects at none against Gravity!'s 1. Stars Units Sizes Objects also leads on rating (4.2 vs 3.9) and iOS requirement (11.0 vs 15.6). Gravity!'s advantage is ads (none vs shown) and update cadence (every 2 months vs every 4 months). On price, review sentiment and device support there is nothing between them.

Both are free to download. Gravity! sells 1 one-off in-app purchase. Stars Units Sizes Objects asks for nothing beyond the download.

Stars Units Sizes Objects holds the better App Store score, 4.2 against 3.9. Both are backed by a comparable volume of ratings — 18 and 5 respectively. Written reviews point the same way: 74% of Gravity!'s written reviews are positive against 80% of Stars Units Sizes Objects's.

Gravity! ships an update every 2 months, Stars Units Sizes Objects every 4 months. The most recent releases landed on August 6, 2026 and September 7, 2026 respectively.

## The numbers

| Metric | Gravity! | Stars Units Sizes Objects |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.9 (18 ratings)](https://appshunter.io/ios/app/gravity/id738871919/reviews) | **[4.2 (5 ratings)](https://appshunter.io/ios/app/stars-units-sizes-objects/id1576148571/reviews)** |
| Number of ratings | **18** | 5 |
| Positive reviews | 73.5% of reviews | **80.0% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | **Every 2 months** | Every 4 months |
| Monetization | Free with in-app purchases | **Ad-supported** |
| Size | 17 MB | 124 MB |
| Requires iOS | 15.6 | **11.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Marc Davis](https://appshunter.io/developer/1010892850) | [Mudarmeen Munlin](https://appshunter.io/developer/1348165664) |

## What reviewers say

### Gravity!

[App page](https://appshunter.io/ios/app/gravity/id738871919)

Simulate the forces of gravity by flinging particles and observing their interactions. Create celestial bodies like planets and black holes, and customize their properties. Explore vast cosmic simulations with intuitive zoom and pan controls.

**Highlights:** Gravity simulation, Particle interaction, Create solar systems, Add black holes, Adjust particle properties, Zoom and pan controls

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Gravity! Extended Edition | $0.99 | one-time |


### Stars Units Sizes Objects

[App page](https://appshunter.io/ios/app/stars-units-sizes-objects/id1576148571)

Explore the vastness of the universe, from the smallest particles to the largest cosmic structures. Compare object sizes, view detailed images, and perform unit conversions across a wide range of astronomical scales. Learn about stars, galaxies, and the incredible distances between them.

**Highlights:** Compare object sizes, View object images, Pinch/Zoom and Pan images, Unit conversion for distances, Explore scales from Planck length to observable universe, Learn about stars and galaxies

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Gravity! free?

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

### Is Stars Units Sizes Objects free?

Stars Units Sizes Objects is free to download, with no in-app purchases.

### Which has better reviews, Gravity! or Stars Units Sizes Objects?

Stars Units Sizes Objects is rated higher. Gravity! averages 3.9 out of 5 from 18 ratings, while Stars Units Sizes Objects averages 4.2 from 5 ratings.

### Do Gravity! or Stars Units Sizes Objects have ads?

Stars Units Sizes Objects shows ads; Gravity! does not.

### Which is updated more often, Gravity! or Stars Units Sizes Objects?

Gravity! ships an update every 2 months, and Stars Units Sizes Objects every 4 months. Most recently, Gravity! was updated on August 6, 2026 and Stars Units Sizes Objects on September 7, 2026.

---

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