# Prime Factors vs PFD Calc

The clearest difference is price: PFD Calc at Free against Prime Factors's $0.99. PFD Calc also leads on update cadence (every 5 weeks vs every 21 months) and iOS requirement (15.0 vs 18.0). Prime Factors's advantage is ads (none vs shown). On in-app purchases and device support there is nothing between them.

PFD Calc is free to download; Prime Factors costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Prime Factors ships an update every 21 months, PFD Calc every 5 weeks. The most recent releases landed on September 10, 2026 and September 17, 2026 respectively.

## The numbers

| Metric | Prime Factors | PFD Calc |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | **[3.9 (24 ratings)](https://appshunter.io/ios/app/prime-factors/id741746948/reviews)** | — |
| Number of ratings | **24** | — |
| Positive reviews | 78.6% of reviews | — |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 21 months | **Every 5 weeks** |
| Monetization | Free | — |
| Size | 1 MB | 14 MB |
| Requires iOS | 18.0 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Paul Hangas](https://appshunter.io/developer/433121902) | [Kazuhisa Kobayashi](https://appshunter.io/developer/1580882000) |

## What reviewers say

### Prime Factors

[App page](https://appshunter.io/ios/app/prime-factors/id741746948)

Explore numbers up to one trillion, with primes clearly marked. Tap any number to reveal its prime factors. Easily navigate to specific numbers using the search function and adjust the display with pinch-to-zoom gestures.

**Highlights:** View numbers up to 1 trillion, Prime numbers highlighted, Tap for prime factors, Search for specific numbers, Pinch and zoom display

**Features:** macOS Compatibility

**In-app purchases:** none


### PFD Calc

[App page](https://appshunter.io/ios/app/pfd-calc-prime-factorization/id6737405828)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Prime Factors free?

Prime Factors costs $0.99, with no in-app purchases.

### Is PFD Calc free?

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

### Do Prime Factors or PFD Calc have ads?

PFD Calc shows ads; Prime Factors does not.

### Which is updated more often, Prime Factors or PFD Calc?

Prime Factors ships an update every 21 months, and PFD Calc every 5 weeks. Most recently, Prime Factors was updated on September 10, 2026 and PFD Calc on September 17, 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.*