CosmoCalc vs Unistellar
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
CosmoCalc
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.
- 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
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CosmoCalc is a simple cosmological distance calculator. With a simple and intuitive interface you can quickly set a reference cosmology and redshift, and CosmoCalc will calculate a full suite of astronomical distances and scales. CosmoCalc is a useful and educational reference tool for astronomers, astronomy students, and anybody interested in calculating the distance to astronomical sources. CosmoCalc allows you to: * Select cosmological parameters H_0, Ω_m, and Ω_Λ with simple touch-screen controls * Easily choose from common reference cosmologies, including Planck 2013, WMAP9, Concordance, and Einstein-deSitter * Quickly determine the luminosity distance, angular diameter distance, lookback time, age of the Universe, comoving volume, and critical density * Easily switch between flat and non-flat cosmologies by clicking on the chain
Unistellar
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.
- Telescope control
- Explore 5000+ celestial objects
- Live astronomical observation
- Instant image sharing
- RAW image download
- Citizen science missions
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The Unistellar App is your command center for all Unistellar telescopes, designed to help astronomers explore the cosmos with ease. 1. Control your telescope: align, point, and operate your smart telescope directly from the App. 2. Explore 5000 celestial objects: galaxies, nebulae, star clusters, planets, Moon, Sun, comets, and asteroids. 3. Observe live: see your target appear within seconds, with more details and colors revealed as the signal accumulates. 4. Share instantly: save your images as PNGs and share them in one click. 5. Go pro: download RAW images for advanced post-processing. 6. Join citizen science missions: contribute to real research with NASA and SETI—track asteroids, detect exoplanets, and more.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | CosmoCalc | Unistellar |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (4 ratings) — better | 3.8 (101 ratings) |
| Positive reviews | 100.0% of reviews — better | 44.3% of reviews |
| Number of ratings | 4 | 101 — better |
| Update frequency | Every 6 months | Every 5 weeks — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPod | iPhone, iPad |
| Requires iOS | 9.0 — better | 18.0 |
| Further details — not scored | ||
| Size | 1 MB | 524 MB |
| Age rating | 4+ | 4+ |
| Developer | Eli Rykoff | Unistellar |
Customer experience
CosmoCalc
Unistellar
In-app purchases
CosmoCalc
No in-app purchases
Unistellar
No in-app purchases
Questions
Is CosmoCalc free?
Is Unistellar free?
Which has better reviews, CosmoCalc or Unistellar?
Do CosmoCalc or Unistellar have ads?
Which is updated more often, CosmoCalc or Unistellar?
Other comparisons
