# SlimCal vs KnowWhen

The clearest difference is in-app purchases: KnowWhen at none against SlimCal's 2. SlimCal's advantage is iOS requirement (16.0 vs 18.0). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. SlimCal sells 2 in-app purchases, starting at $9.99 per month. KnowWhen asks for nothing beyond the download.

Both ship on a similar rhythm, roughly every 3 months. The most recent releases landed on October 4, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | SlimCal | KnowWhen |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/knowwhen/id6758948095/reviews)** |
| Number of ratings | — | **1** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 months | Every 3 months |
| Monetization | — | Free |
| Size | 48 MB | 6 MB |
| Requires iOS | **16.0** | 18.0 |
| Devices | iPhone | iPhone |
| Age rating | 12+ | 17+ |
| Developer | [Regina Rachma Agnia](https://appshunter.io/developer/1820575153) | [Launch Round](https://appshunter.io/developer/1580265297) |

## What reviewers say

### SlimCal

[App page](https://appshunter.io/ios/app/slimcal-ai-calorie-tracker/id6747279272)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Slimora Pro Monthly | $9.99 | per month |
| Slimora Pro Yearly | $49.99 | per year |


### KnowWhen

[App page](https://appshunter.io/ios/app/knowwhen/id6758948095)

This app offers simple, timely guidance for husbands based on their partner's cycle. It helps users understand when to offer support, listen, or give space, fostering better connection and reducing relationship tension.

**Highlights:** Daily simple guidance, Phase-based reminders, Private logging for patterns, Discreet data storage on device, Guidance on giving space, Guidance on offering support

**In-app purchases:** none


## Frequently asked questions

### Is SlimCal free?

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

### Is KnowWhen free?

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

### Do SlimCal or KnowWhen have ads?

Neither SlimCal nor KnowWhen shows ads.

### Which is updated more often, SlimCal or KnowWhen?

SlimCal ships an update every 3 months, and KnowWhen every 3 months. Most recently, SlimCal was updated on October 4, 2026 and KnowWhen on October 10, 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.*