# Timer 555 Calculator Pro vs Red stone diamond

The clearest difference is price: Red stone diamond at Free against Timer 555 Calculator Pro's $0.99. Red stone diamond also leads on update cadence (every 6 weeks vs every 3 months). Timer 555 Calculator Pro's advantage is iOS requirement (13.2 vs 15.6). On ads, in-app purchases and device support there is nothing between them.

Red stone diamond is free to download; Timer 555 Calculator Pro costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Timer 555 Calculator Pro ships an update every 3 months, Red stone diamond every 6 weeks. The most recent releases landed on October 23, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | Timer 555 Calculator Pro | Red stone diamond |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | **[4.7 (3 ratings)](https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125/reviews)** | — |
| Number of ratings | **3** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 6 weeks** |
| Monetization | Paid | — |
| Size | 3 MB | 59 MB |
| Requires iOS | **13.2** | 15.6 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [ATAL PRAKASH SHAH](https://appshunter.io/developer/1799118811) |

## What reviewers say

### Timer 555 Calculator Pro

[App page](https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125)

Calculate parameters for monostable and astable circuits. Find component combinations for desired pulse width or frequency. Share circuit files via iCloud Drive or AirDrop.

**Highlights:** Calculate monostable pulse width, Calculate astable frequency, Find component combinations, Adjust component tolerance, Unlimited combinations (Pro), Share circuit files

**In-app purchases:** none


### Red stone diamond

[App page](https://appshunter.io/ios/app/red-stone-diamond/id6742638456)

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

**In-app purchases:** none


## Frequently asked questions

### Is Timer 555 Calculator Pro free?

Timer 555 Calculator Pro costs $0.99, with no in-app purchases.

### Is Red stone diamond free?

Red stone diamond is free to download, with no in-app purchases.

### Do Timer 555 Calculator Pro or Red stone diamond have ads?

Neither Timer 555 Calculator Pro nor Red stone diamond shows ads.

### Which is updated more often, Timer 555 Calculator Pro or Red stone diamond?

Timer 555 Calculator Pro ships an update every 3 months, and Red stone diamond every 6 weeks. Most recently, Timer 555 Calculator Pro was updated on October 23, 2026 and Red stone diamond on October 28, 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.*