# CosmoCalc vs Unistellar

The clearest difference is review sentiment: CosmoCalc at 100% against Unistellar's 44%. CosmoCalc also leads on rating (5.0 vs 3.8) and iOS requirement (9.0 vs 18.0). Unistellar's advantage is update cadence (every 5 weeks vs every 6 months) and ratings volume (101 vs 4). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

CosmoCalc holds the better App Store score, 5.0 against 3.8. That said, the two scores are not equally well evidenced: Unistellar has 101 ratings behind it against 4, so its average is the more settled of the two. Written reviews point the same way: 100% of CosmoCalc's written reviews are positive against 44% of Unistellar's.

CosmoCalc ships an update every 6 months, Unistellar every 5 weeks. The most recent releases landed on October 6, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | CosmoCalc | Unistellar |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (4 ratings)](https://appshunter.io/ios/app/cosmocalc/id334569654/reviews)** | [3.8 (101 ratings)](https://appshunter.io/ios/app/unistellar/id1435141427/reviews) |
| Number of ratings | 4 | **101** |
| Positive reviews | **100.0% of reviews** | 44.3% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 5 weeks** |
| Monetization | Free | Free |
| Size | 1 MB | 524 MB |
| Requires iOS | **9.0** | 18.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Eli Rykoff](https://appshunter.io/developer/318275933) | [Unistellar](https://appshunter.io/developer/1384354590) |

## What reviewers say

### CosmoCalc

[App page](https://appshunter.io/ios/app/cosmocalc/id334569654)

This app calculates astronomical distances and scales based on user-selected cosmological parameters. It offers a simple interface for astronomers, students, and enthusiasts to quickly determine various cosmic measurements.

**Highlights:** Select cosmological parameters (H0, Ωm, ΩΛ), Choose from common reference cosmologies, Calculate luminosity distance, Determine angular diameter distance, Calculate lookback time, Find age of the Universe, Compute comoving volume and critical density

**Features:** macOS Compatibility

**In-app purchases:** none


### Unistellar

[App page](https://appshunter.io/ios/app/unistellar/id1435141427)

Control your smart telescope, explore thousands of celestial objects, and observe them live. Save and share your discoveries, or contribute to real scientific research with citizen science missions.

**Highlights:** Telescope control, Explore 5000+ celestial objects, Live astronomical observation, Instant image sharing, RAW image download, Citizen science missions

**In-app purchases:** none


## Frequently asked questions

### Is CosmoCalc free?

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

### Is Unistellar free?

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

### Which has better reviews, CosmoCalc or Unistellar?

CosmoCalc is rated higher. CosmoCalc averages 5.0 out of 5 from 4 ratings, while Unistellar averages 3.8 from 101 ratings.

### Do CosmoCalc or Unistellar have ads?

Neither CosmoCalc nor Unistellar shows ads.

### Which is updated more often, CosmoCalc or Unistellar?

CosmoCalc ships an update every 6 months, and Unistellar every 5 weeks. Most recently, CosmoCalc was updated on October 6, 2026 and Unistellar on October 25, 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.*