# Hello Sun vs Prism

The clearest difference is iOS requirement: Hello Sun at 13.0 against Prism's 26.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Hello Sun sells 2 in-app purchases, starting at $3.99 per month and Prism sells 1 in-app purchase, starting at $1.99 per month. Whichever you choose, the download price is not the number that matters.

Hello Sun ships an update weekly, Prism every 11 days. The most recent releases landed on October 24, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | Hello Sun | Prism |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/hello-sun-vitamin-d-tracker/id6756599125/reviews)** | — |
| Number of ratings | **1** | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Weekly** | Every 11 days |
| Monetization | Freemium | — |
| Size | 62 MB | 3 MB |
| Requires iOS | **13.0** | 26.0 |
| Devices | iPhone, iPod | **iPhone, iPad, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [Kyle Brammer](https://appshunter.io/developer/1861694771) | [剑炜 陈](https://appshunter.io/developer/1868267178) |

## What reviewers say

### Hello Sun

[App page](https://appshunter.io/ios/app/hello-sun-vitamin-d-tracker/id6756599125)

Track vitamin D intake from sunlight and supplements with safe, burn-aware timers. Offers personalized estimates and weekly progress tracking, adapting to your skin and location for optimal sun exposure.

**Highlights:** Safe sun session timers, Vitamin D IU estimates, Log supplements and sun, Adaptive acclimation, Weekly progress tracking, UV forecast planning, Winter Mode support

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Hello Sun Plus Monthly Subscription | $3.99 | per month |
| Hello Sun Plus Yearly Subscription | $29.99 | per year |


### Prism

[App page](https://appshunter.io/ios/app/prism-sunlight-tracker/id6758259341)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Prism Premium (Monthly) | $1.99 | per month |


## Frequently asked questions

### Is Hello Sun free?

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

### Is Prism free?

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

### Do Hello Sun or Prism have ads?

Neither Hello Sun nor Prism shows ads.

### Which is updated more often, Hello Sun or Prism?

Hello Sun ships an update weekly, and Prism every 11 days. Most recently, Hello Sun was updated on October 24, 2026 and Prism on October 28, 2026.

---

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