# Calculi vs Discover Douglas

The clearest difference is in-app purchases: Discover Douglas at none against Calculi's 4. Calculi's advantage is device support (4 vs 1). On price, update cadence, ads and iOS requirement there is nothing between them.

Both are free to download. Calculi sells 4 in-app purchases, starting at $2.99 per year. Discover Douglas asks for nothing beyond the download.

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on November 4, 2026 and November 8, 2026 respectively.

## The numbers

| Metric | Calculi | Discover Douglas |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.4 (383 ratings)](https://appshunter.io/ios/app/calculi-scientific-calculator/id452182503/reviews)** | — |
| Number of ratings | **383** | — |
| Positive reviews | 51.3% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 months | Every 2 months |
| Monetization | Free with in-app purchases | — |
| Size | 43 MB | 142 MB |
| Requires iOS | 17.6 | 17.6 |
| Devices | **iPhone, iPad, Apple TV, Apple Watch** | iPhone |
| Age rating | 4+ | 12+ |
| Developer | [Michael Natole, Jr.](https://appshunter.io/developer/443621043) | [City of Douglas (Wyoming)](https://appshunter.io/developer/1784817555) |

## What reviewers say

### Calculi

[App page](https://appshunter.io/ios/app/calculi-scientific-calculator/id452182503)

A smart and powerful calculator designed for ease of use, offering advanced scientific functions, unit and currency conversion, and a supercharged history tape. It adapts to various devices and supports external keyboards for enhanced functionality.

**Highlights:** Complex expression solving, Unit conversion (17 categories), Currency conversion (30+ currencies), Scientific constants, Supercharged history tape, iMessage app integration, Apple Watch app

**Features:** macOS Compatibility

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Calculi Pro | $2.99 | per year |
| Small Tip | $0.99 | one-time |
| Medium Tip | $2.99 | one-time |
| Large Tip | $4.99 | one-time |

**What reviewers like**

- 👍 Better than stock iPhone calculator
- 📈 History screen with past answers/expressions
- 🔄 Regular helpful updates
- ⌨️ Works with keyboard
- 🗂️ Works in Split Screen

**What reviewers complain about**

- ⚠️ Pop-up rating requests
- 💸 Added ads in updates
- 🎛️ Clutter of unused keys on iPad
- 🐛 Buggy history feature
- 💥 Crashes during multiplication

**Reported bugs**

- Calculation not appearing in history until app restart
- New calculation replaces previous in history tile
- Crashes when multiplying by 1.03
- Physical iPad keyboard not recognized
- App crashes/closes on iPad iOS 13

**Requested features**

- Option for Dark Mode all the time
- Option to choose icons
- Fix Slide Over functionality


### Discover Douglas

[App page](https://appshunter.io/ios/app/discover-douglas/id6739315607)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Calculi free?

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

### Is Discover Douglas free?

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

### Do Calculi or Discover Douglas have ads?

Neither Calculi nor Discover Douglas shows ads.

### Which is updated more often, Calculi or Discover Douglas?

Calculi ships an update every 2 months, and Discover Douglas every 2 months. Most recently, Calculi was updated on November 4, 2026 and Discover Douglas on November 8, 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.*