# CalmTide vs Isla

The clearest difference is device support: CalmTide at 3 against Isla's 1. CalmTide also leads on iOS requirement (18.6 vs 26.0). On price, ads and in-app purchases there is nothing between them.

Both are free to download. CalmTide sells 3 in-app purchases, starting at $4.99 per month and Isla sells 2 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

## The numbers

| Metric | CalmTide | Isla |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 10 days | — |
| Size | 9 MB | 2 MB |
| Requires iOS | **18.6** | 26.0 |
| Devices | **iPhone, iPad, Apple Watch** | iPhone |
| Age rating | 12+ | 4+ |
| Developer | [Michael Smith](https://appshunter.io/developer/1893971383) | [Markus Vaha](https://appshunter.io/developer/1706287937) |

## What reviewers say

### CalmTide

[App page](https://appshunter.io/ios/app/calmtide-cortisol-tracker/id6776101012)

**Features:** Apple Watch app

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $4.99 | per month |
| Annual | $29.99 | per year |
| Lifetime | $59.99 | one-time |


### Isla

[App page](https://appshunter.io/ios/app/isla-nervous-system-reset/id6784335577)

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Isla Premium — Monthly | $4.99 | per month |
| Isla Premium — Yearly | $29.99 | per year |


## Frequently asked questions

### Is CalmTide free?

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

### Is Isla free?

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

### Do CalmTide or Isla have ads?

Neither CalmTide nor Isla shows ads.

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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.*