# NFP Calendar vs Chart35

The clearest difference is update cadence: Chart35 at every 6 days against NFP Calendar's every 2 months. Chart35 also leads on rating (5.0 vs 4.7) and device support (4 vs 2). NFP Calendar's advantage is ratings volume (3 vs 1). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Chart35 holds the better App Store score, 5.0 against 4.7. Both are backed by a comparable volume of ratings — 3 and 1 respectively.

NFP Calendar ships an update every 2 months, Chart35 every 6 days. The most recent releases landed on October 22, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | NFP Calendar | Chart35 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.7 (3 ratings)](https://appshunter.io/ios/app/nfp-calendar/id6751753267/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/chart35/id6784113411/reviews)** |
| Number of ratings | **3** | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 6 days** |
| Monetization | Free | Free |
| Size | 8 MB | 5 MB |
| Requires iOS | 26.0 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod, Apple Watch** |
| Age rating | 12+ | 4+ |
| Developer | [Esteban Cervera](https://appshunter.io/developer/1209785445) | [Stephens Page LLC](https://appshunter.io/developer/6777773686) |

## What reviewers say

### NFP Calendar

[App page](https://appshunter.io/ios/app/nfp-calendar/id6751753267)

Track your fertility naturally using various methods like Creighton or Billings. Record daily observations, manage your cycle, and export data for your instructor or doctor. Designed specifically for Natural Family Planning users.

**Highlights:** Record mucus observations, Track menstrual flow, Log intercourse timing, Automatic cycle detection, Generate PDF charts, Export data as JSON, iCloud sync

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

**In-app purchases:** none


### Chart35

[App page](https://appshunter.io/ios/app/chart35/id6784113411)

This app helps users privately track their fertility observations using the Creighton Model FertilityCare System. It offers offline functionality, color-coded stamps, and various chart views. Users can securely share their data with practitioners.

**Highlights:** Creighton Model charting, Offline-first functionality, Color-coded observation stamps, Chart and calendar views, Peak day and post-peak tracking, Secure practitioner sharing

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is NFP Calendar free?

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

### Is Chart35 free?

Chart35 is free to download, with no in-app purchases.

### Which has better reviews, NFP Calendar or Chart35?

Chart35 is rated higher. NFP Calendar averages 4.7 out of 5 from 3 ratings, while Chart35 averages 5.0 from 1 ratings.

### Do NFP Calendar or Chart35 have ads?

Neither NFP Calendar nor Chart35 shows ads.

### Which is updated more often, NFP Calendar or Chart35?

NFP Calendar ships an update every 2 months, and Chart35 every 6 days. Most recently, NFP Calendar was updated on October 22, 2026 and Chart35 on October 25, 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.*