# Decay calc vs AutoZHEN

The clearest difference is in-app purchases: AutoZHEN at none against Decay calc's 1. AutoZHEN also leads on iOS requirement (13.0 vs 15.2). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Decay calc sells 1 one-off in-app purchase. AutoZHEN asks for nothing beyond the download.

Decay calc ships an update every 3 months, AutoZHEN every 2 months. The most recent releases landed on October 8, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | Decay calc | AutoZHEN |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[1.0 (1 ratings)](https://appshunter.io/ios/app/decay-calc/id1479526735/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 2 months** |
| Monetization | Free with in-app purchases | — |
| Size | 27 MB | 28 MB |
| Requires iOS | 15.2 | **13.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | 17+ |
| Developer | [Alexey Baranov](https://appshunter.io/developer/1479526734) | [深圳市易车合创科技有限公司](https://appshunter.io/developer/1022244877) |

## What reviewers say

### Decay calc

[App page](https://appshunter.io/ios/app/decay-calc/id1479526735)

This tool calculates the decay of radioactive isotopes over time, considering half-life for accurate activity predictions. It's useful in nuclear medicine, environmental monitoring, and radiation safety for handling and disposal of materials.

**Highlights:** Radioactive isotope decay calculation, Half-life integration, Activity prediction, Decay constant determination, Radiation dose calculation

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Radio calc | $0.99 | one-time |


### AutoZHEN

[App page](https://appshunter.io/ios/app/autozhen/id6648759620)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Decay calc free?

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

### Is AutoZHEN free?

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

### Do Decay calc or AutoZHEN have ads?

Neither Decay calc nor AutoZHEN shows ads.

### Which is updated more often, Decay calc or AutoZHEN?

Decay calc ships an update every 3 months, and AutoZHEN every 2 months. Most recently, Decay calc was updated on October 8, 2026 and AutoZHEN 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.*