# Interval Flow vs Watch Hydration

The clearest difference is in-app purchases: Watch Hydration at none against Interval Flow's 1. Interval Flow's advantage is iOS requirement (15.6 vs 17.6). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Interval Flow sells 1 one-off in-app purchase. Watch Hydration asks for nothing beyond the download.

Interval Flow ships an update every 2 weeks, Watch Hydration every 3 weeks. The most recent releases landed on September 8, 2026 and September 19, 2026 respectively.

## The numbers

| Metric | Interval Flow | Watch Hydration |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 2 weeks** | Every 3 weeks |
| Size | 8 MB | 2 MB |
| Requires iOS | **15.6** | 17.6 |
| Devices | **iPhone, iPod, Apple Watch** | iPhone, Apple Watch |
| Age rating | 4+ | 4+ |
| Developer | [Tegyaan](https://appshunter.io/developer/1711584632) | [Thomas Chatting](https://appshunter.io/developer/1811425476) |

## What reviewers say

### Interval Flow

[App page](https://appshunter.io/ios/app/interval-flow/id6469113776)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Multiple Programs | $3.99 | one-time |


### Watch Hydration

[App page](https://appshunter.io/ios/app/watch-hydration/id6745416167)

**Features:** Apple Watch app

**In-app purchases:** none


## Frequently asked questions

### Is Interval Flow free?

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

### Is Watch Hydration free?

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

### Do Interval Flow or Watch Hydration have ads?

Neither Interval Flow nor Watch Hydration shows ads.

### Which is updated more often, Interval Flow or Watch Hydration?

Interval Flow ships an update every 2 weeks, and Watch Hydration every 3 weeks. Most recently, Interval Flow was updated on September 8, 2026 and Watch Hydration on September 19, 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.*