# Diesel CO2 vs CalcFast

The clearest difference is update cadence: CalcFast at every 2 months against Diesel CO2's every 10 months. Diesel CO2's advantage is iOS requirement (15.6 vs 27.1). On price, ads, in-app purchases and device support there is nothing between them.

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

Diesel CO2 ships an update every 10 months, CalcFast every 2 months. The most recent releases landed on October 15, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Diesel CO2 | CalcFast |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.2 (21 ratings)](https://appshunter.io/ios/app/calcfast/id876781417/reviews)** |
| Number of ratings | — | **21** |
| Positive reviews | — | 78.3% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 10 months | **Every 2 months** |
| Monetization | — | Free |
| Size | 2 MB | 6 MB |
| Requires iOS | **15.6** | 27.1 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Addison Mai](https://appshunter.io/developer/391450820) | [Hannes Sverrisson](https://appshunter.io/developer/428851947) |

## What reviewers say

### Diesel CO2

[App page](https://appshunter.io/ios/app/diesel-co2/id471325738)

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

**In-app purchases:** none


### CalcFast

[App page](https://appshunter.io/ios/app/calcfast/id876781417)

A fast and elegant calculator for Apple devices that displays your calculation history. It offers a Today Extension for quick access and supports Apple Watch, external keyboards, and VoiceOver.

**Highlights:** Calculation history display, Today Extension for quick calculations, Apple Watch app, Dark/light mode selection, External keyboard support, VoiceOver support

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

**In-app purchases:** none


## Frequently asked questions

### Is Diesel CO2 free?

Diesel CO2 is free to download, with no in-app purchases.

### Is CalcFast free?

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

### Do Diesel CO2 or CalcFast have ads?

Neither Diesel CO2 nor CalcFast shows ads.

### Which is updated more often, Diesel CO2 or CalcFast?

Diesel CO2 ships an update every 10 months, and CalcFast every 2 months. Most recently, Diesel CO2 was updated on October 15, 2026 and CalcFast on October 30, 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.*