# KalcuLytes vs FP Notebook

The clearest difference is rating: FP Notebook at 4.9 against KalcuLytes's 3.0. FP Notebook also leads on ratings volume (3.4K vs 2) and chart position (#55 vs unranked). KalcuLytes's advantage is monetization model (free with in-app purchases vs subscription) and iOS requirement (9.3 vs 15.0). On price, review sentiment, update cadence and ads there is nothing between them.

Both are free to download. KalcuLytes sells 4 one-off in-app purchases and FP Notebook sells 3 in-app purchases, starting at $1.99 per month. Whichever you choose, the download price is not the number that matters.

FP Notebook holds the better App Store score, 4.9 against 3.0. That said, the two scores are not equally well evidenced: FP Notebook has 3.4K ratings behind it against 2, so its average is the more settled of the two. Written reviews complicate that: 67% of KalcuLytes's written reviews are positive against 61% of FP Notebook's, so the app with the better star average is not the one people write more warmly about.

KalcuLytes ships an update every 3 months, FP Notebook every 2 months. The most recent releases landed on October 6, 2026 and October 26, 2026 respectively.

## The numbers

| Metric | KalcuLytes | FP Notebook |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.0 (2 ratings)](https://appshunter.io/ios/app/kalculytes-electrolyte-replacement-calculator/id704720994/reviews) | **[4.9 (3.4K ratings)](https://appshunter.io/ios/app/fp-notebook/id835973313/reviews)** |
| Number of ratings | 2 | **3.4K** |
| Positive reviews | **66.7% of reviews** | 61.1% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 2 months** |
| Monetization | **Free with in-app purchases** | Subscription |
| Best chart rank | — | **#55** |
| Size | 5 MB | 141 MB |
| Requires iOS | **9.3** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | 17+ |
| Developer | [KABBA, LLC](https://appshunter.io/developer/704720997) | [Atmosphere Apps, Inc.](https://appshunter.io/developer/334077424) |

## What reviewers say

### KalcuLytes

[App page](https://appshunter.io/ios/app/kalculytes-electrolyte-replacement-calculator/id704720994)

This medical app calculates and recommends doses for Magnesium, Phosphorus, and Potassium replacement in adult patients. It offers intravenous and oral/enteral administration routes, individualizing doses based on patient factors.

**Highlights:** Calculate Magnesium, Phosphorus, Potassium doses, Recommend mode of administration, Intravenous and oral/enteral routes, Individualized dosing based on patient data, View target electrolyte ranges

**Features:** macOS Compatibility

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlimited use of Magnesium | $2.99 | one-time |
| Unlimited use of Phosphorus | $2.99 | one-time |
| Unlimited use of Potassium | $2.99 | one-time |
| Unlimited use of All Elements | $6.99 | one-time |


### FP Notebook

[App page](https://appshunter.io/ios/app/fp-notebook/id835973313)

**Currently charting:** #55 Top Grossing · Medical (US App Store)

A comprehensive medical reference for primary care and emergency clinicians, offering rapid access to over 6100 interlinked topic pages. Content is updated monthly through literature reviews and conferences, providing up-to-date information for medical professionals.

**Highlights:** Rapid access medical reference, Over 6100 interlinked topic pages, Content updated monthly, 31 specialty books, 700+ chapters, Point-of-care tool

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Subscription | $1.99 | per month |
| Annual Subscription | $19.99 | per year |
| Annual Sub | $24.99 | per year |

**What reviewers like**

- 🌟 Excellent, comprehensive medical reference
- ⚡️ Efficient, concise, and easy to use
- 🧠 Invaluable for medical students, residents, and practitioners
- 🤝 Highly recommended by users
- 🕰️ Frequently used and relied upon for years

**What reviewers complain about**

- 💰 Subscription model frustrates some users who previously had free access
- 🐞 Occasional app freezing or crashing issues reported
- 🔍 Built-in search function could be improved

**Reported bugs**

- App freezing or crashing on certain devices
- Subscription issues or unexpected charges

**Requested features**

- Ability to earn continuing education credits through the app
- Improved search functionality


## Frequently asked questions

### Is KalcuLytes free?

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

### Is FP Notebook free?

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

### Which has better reviews, KalcuLytes or FP Notebook?

FP Notebook is rated higher. KalcuLytes averages 3.0 out of 5 from 2 ratings, while FP Notebook averages 4.9 from 3.4K ratings.

### Do KalcuLytes or FP Notebook have ads?

Neither KalcuLytes nor FP Notebook shows ads.

### Which is updated more often, KalcuLytes or FP Notebook?

KalcuLytes ships an update every 3 months, and FP Notebook every 2 months. Most recently, KalcuLytes was updated on October 6, 2026 and FP Notebook on October 26, 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.*