# Is it Prime? vs Kalc

The clearest difference is rating: Kalc at 4.7 against Is it Prime?'s 3.2. Kalc also leads on update cadence (every 9 days vs every 74 months) and review sentiment (96% vs 71%). On price, ratings volume, ads and in-app purchases there is nothing between them.

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

Kalc holds the better App Store score, 4.7 against 3.2. Both are backed by a comparable volume of ratings — 5 and 3 respectively. Written reviews point the same way: 71% of Is it Prime?'s written reviews are positive against 96% of Kalc's.

Is it Prime? ships an update every 74 months, Kalc every 9 days. Both last shipped on October 23, 2026.

## The numbers

| Metric | Is it Prime? | Kalc |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.2 (5 ratings)](https://appshunter.io/ios/app/is-it-prime/id326095651/reviews) | **[4.7 (3 ratings)](https://appshunter.io/ios/app/kalc/id610991936/reviews)** |
| Number of ratings | **5** | 3 |
| Positive reviews | 71.4% of reviews | **96.2% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 74 months | **Every 9 days** |
| Monetization | Free | Free |
| Size | 1 MB | 24 MB |
| Requires iOS | 15.0 | **13.4** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Wismar](https://appshunter.io/developer/307757950) | [YUTA OKAJIMA](https://appshunter.io/developer/610991939) |

## What reviewers say

### Is it Prime?

[App page](https://appshunter.io/ios/app/is-it-prime/id326095651)

Enter any number to instantly determine if it is a prime number or not. This straightforward utility provides a quick answer to your mathematical curiosity.

**Highlights:** Prime number identification, Simple number input, Instant yes/no results

**Features:** macOS Compatibility

**In-app purchases:** none


### Kalc

[App page](https://appshunter.io/ios/app/kalc/id610991936)

This utility app offers a unit converter, calculator, and world clock. Its user-friendly interface is designed for quick access to everyday calculations and conversions.

**Highlights:** Unit converter, Calculator, World clock, Simple UI, Quick results

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Is it Prime? free?

Is it Prime? is free to download, with no in-app purchases.

### Is Kalc free?

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

### Which has better reviews, Is it Prime? or Kalc?

Kalc is rated higher. Is it Prime? averages 3.2 out of 5 from 5 ratings, while Kalc averages 4.7 from 3 ratings.

### Do Is it Prime? or Kalc have ads?

Neither Is it Prime? nor Kalc shows ads.

### Which is updated more often, Is it Prime? or Kalc?

Is it Prime? ships an update every 74 months, and Kalc every 9 days. Most recently, Is it Prime? was updated on October 23, 2026 and Kalc on October 23, 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.*