# Decay calc vs LDM Valves

The clearest difference is in-app purchases: LDM Valves at none against Decay calc's 1. 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. LDM Valves asks for nothing beyond the download.

Decay calc ships an update every 3 months, LDM Valves every 5 months. The most recent releases landed on October 8, 2026 and October 17, 2026 respectively.

## The numbers

| Metric | Decay calc | LDM Valves |
| --- | --- | --- |
| 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 5 months |
| Monetization | Free with in-app purchases | — |
| Size | 27 MB | 37 MB |
| Requires iOS | **15.2** | 15.3 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | 4+ |
| Developer | [Alexey Baranov](https://appshunter.io/developer/1479526734) | [LDM, spol. s r.o.](https://appshunter.io/developer/1807390383) |

## 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 |


### LDM Valves

[App page](https://appshunter.io/ios/app/ldm-valves/id6744373442)

**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 LDM Valves free?

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

### Do Decay calc or LDM Valves have ads?

Neither Decay calc nor LDM Valves shows ads.

### Which is updated more often, Decay calc or LDM Valves?

Decay calc ships an update every 3 months, and LDM Valves every 5 months. Most recently, Decay calc was updated on October 8, 2026 and LDM Valves on October 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.*