Calca vs Things 3
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Calca
This app is an advanced symbolic calculator and text editor. It solves equations, simplifies expressions, and allows you to explain your work alongside calculations. Calculations update instantly as you type, and all data is stored as plain text for easy sharing and device syncing.
- Symbolic calculation
- Equation solving
- Expression simplification
- Markdown text editor
- Real-time updates
- Unit and currency conversion
- Matrix operations
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Calca is a powerful symbolic calculator that gives you instant answers as you type. It solves equations and simplifies complex expressions - it's a computer algebra system in your pocket! It's also a rich Markdown text editor so that you can explain your ideas alongside your calculations. Calca is perfect for professionals and students - anyone who works with numbers and equations. Variables and functions can be created with only a few keystrokes and can be manipulated with a rich library of operators and functions. Calca updates as you type - just like a spreadsheet. You can declare variables, edit their values and watch everything update before your eyes. Since everything is calculated on the device - no network needed - you get answers instantaneously. All calculations are stored as plain text so you can easily share them with other editors and move them from device to device. Calca has been designed to work with iCloud documents so all your devices can access your calculations - you'll always have the latest files ready for viewing and editing. Calca comes with a suite of examples to help you get started covering topics from home mortgages to kinetics. All these examples are fully explained within Calca itself. Are you still using a desktop calculator? Are you using the calculator with the giant buttons that came with your OS? Computers are much more capable than doing simple one-line arithmetic - put your machine to work with Calca! Calculation Features: • Variables `x = 42` • Functions `f(c) = 9/5*c + 32` and even recursive functions • Units `42 mph in kmph` and currency `¥599 in $` • Solves equations (`x + 2x + 4x = 42`, what is x?) • Matrices with inverses so you can solve linear equations • Sum, prod, map, and reduce operations on lists, matrices, and ranges • Trigonometry and complex numbers • Derivatives of functions • Logic operations and if statements • Binary math (& and |) and support for binary and hex number (`0xA9` and `0b1010`) • Keeps track of units (m, s, m/s, m/s^2, etc.) so you can verify your equations as you compute Please visit http://calca.io to see lots of examples. Thank you for looking!
Things 3
This app helps you organize your life by planning your day, managing projects, and tracking progress toward your goals. It offers a clean interface to manage tasks, projects, and life areas, making it easy to focus on what matters.
- To-Do management
- Project organization
- Area categorization
- Daily planning
- Reminders and repeaters
- Calendar integration
- Share extension
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Get things done! The award-winning Things app helps you plan your day, manage your projects, and make real progress toward your goals. Best of all, it’s easy to use. Within the hour, you’ll have everything off your mind and neatly organized—from routine tasks to your biggest life goals—and you can start focusing on what matters today. “Things offers the best combination of design and functionality of any app we tested, with nearly all the features of other power user applications and a delightful interface that never gets in the way of your work.” —Wirecutter, The New York Times KEY FEATURES • Your To-Dos Your basic building block is the almighty To-Do—each a small step toward a great accomplishment. You can add notes, tag it, schedule it, and break it down into smaller steps. • Your Projects Create a Project for any big goal, then add the to-dos to reach it. Use headings to structure your list as you outline your plan. There’s also a place to jot down your notes, and a deadline to keep you on schedule. • Your Areas Create an Area for each sphere of your life, such as Work, Family, Finance, and so on. This keeps everything neatly organized, and helps you see the big picture as you set your plans in motion. • Your Plan Everything on your schedule is neatly laid out in the Today and Upcoming lists, which show your to-dos and calendar events. Each morning, see what you planned for Today and decide what you want to do. The rest is down to you :) MORE THINGS TO LOVE As you dive deeper, you’ll find Things packed with helpful features. Here are just a few: • Reminders — set a time and Things will remind you. • Repeaters — automatically repeat to-dos on a schedule you set. • This Evening — a special place for your evening plans. • Calendar integration — see your events and to-dos together. • Tags — categorize your to-dos and quickly filter lists. • Quick Find — instantly find to-dos or switch between lists. • Magic Plus — drag the + button to insert to-dos anywhere in a list. • Share extension — create to-dos with content from other apps. • Widgets — see lists on your home/lock screens. • Mail to Things — forward an email to Things; now it’s a to-do. • Markdown — structure & style your notes. • And much more! MADE FOR IPHONE Things is tailored to the iPhone with deep system integrations as well. A great example is the Share extension, which allows you to create to-dos with content from other apps, such as a link to a website you want to get back to. You can also enjoy a beautiful dark mode at sunset, connect your calendars, add a variety of widgets, create to-dos via Siri, import from Reminders—Things can do it all! There’s even Shortcuts integration if you want to automate your workflows. MADE FOR APPLE WATCH Things comes with a great app for Apple Watch. Just raise your wrist to glance at your Today list, mark to-dos complete as you go, and dictate new ones on the fly—all synced instantly with your iPhone, iPad, and Mac. AWARD-WINNING DESIGN Made in Stuttgart, with two Apple Design Awards to its name, Things is a fine example of German engineering: designed not only to look fantastic, but to be perfectly functional as well. Every detail is thoughtfully considered, then polished to perfection. “It’s like the unicorn of productivity tools: deep enough for serious work, surprisingly easy to use, and gorgeous enough to enjoy staring at.” —Apple GET THINGS TODAY Whatever it is you want to accomplish in life, Things can help you get there. Install the app today and see what you can do! • Things is also available for Mac, iPad, and Apple Vision Pro (sold separately). • Sync is provided for free via our Things Cloud service. • A free trial is available for Mac: www.things.app If you have any questions, please get in touch. We provide professional support and will be glad to help you!
Screenshots
Verdict
The clearest difference is in-app purchases: Things 3 at none against Calca's 2. Things 3 also leads on update cadence (fortnightly vs every 5 months) and ratings volume (28K vs 153). On price, review sentiment, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Calca costs $9.99 and Things 3 $9.99 up front. Calca sells 2 one-off in-app purchases. Things 3 asks for nothing beyond the download.
Things 3 holds the better App Store score, 4.8 against 4.5. That said, the two scores are not equally well evidenced: Things 3 has 28K ratings behind it against 153, so its average is the more settled of the two. Written reviews split almost evenly too, at 76% and 76% positive.
Calca ships an update every 5 months, Things 3 fortnightly. Both last shipped on September 25, 2026.
| Parameter | Calca | Things 3 |
|---|---|---|
| Price | $9.99 | $9.99 |
| Rating | 4.5 (153 ratings) | 4.8 (28K ratings) — better |
| Positive reviews | 76.5% of reviews — better | 76.3% of reviews |
| Number of ratings | 153 | 28K — better |
| Update frequency | Every 5 months | Fortnightly — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases — better | Paid |
| Best chart rank | — | #3 — better |
| Devices | iPhone, iPad, iPod — better | iPhone, Apple Watch |
| Requires iOS | 15.0 — better | 16.4 |
| Further details — not scored | ||
| Size | 78 MB | 118 MB |
| Age rating | 4+ | 4+ |
| Developer | Krueger Systems, Inc. | Cultured Code GmbH & Co. KG |
Customer experience
Calca
Things 3
User reviews
Calca
From 153 App Store ratingsWhat we love
- 💡 Unique blend of text editor and calculator
- 📝 Markdown support for documentation
- 🔄 Dynamic recalculation of all values
- ⚙️ Powerful mathematical and algebraic capabilities
- 📊 Unit conversion and unit-aware calculations
Room to improve
- 🐛 Magic Keyboard input bugs on iPad
- ⚠️ Appears abandoned or poorly maintained
- 🐛 Text selection issues with external keyboards
- 📱 iPad landscape mode problems
- 🐛 Cursor jumping and screen jumping during editing
Things 3
From 28K App Store ratingsWhat we love
- 🚀 Smooth and fast
- 👍 Elegant and intuitive design
- 🔒 Secure and private
- 💡 Powerful organization features
- 🗓️ Great calendar integration
Room to improve
- 💰 Expensive for multiple devices
- 🌐 Lack of web/Windows app
- 🔀 Difficulty with task reordering
- 🔔 Lacking persistent notifications
- 📁 No file attachments
Bugs and requests
Calca
Reported bugs
12 issues- Magic Keyboard causes number input to overwrite instead of append
- Text selection before numbers triggers increment/decrement instead of selecting
- Cursor jumps forward and backward with external keyboards
- iPad Pro keyboard truncation in portrait mode
- Arrow key (=>) doesn't work in landscape mode
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- App crashes on startup on some devices
- File saving is temperamental and causes data loss
- Folders don't persist unless calculations created within them
- Large number calculations lose precision (10^100 + 1 - 10^100 returns 0 instead of 1)
- Keyboard focus issues on iPad with Magic Keyboard
- iOS 13+ button adaptation issues
- Spinning beach ball on very large calculations
Requested features
15 requests- Files app and document browser integration
- Dropbox and Google Drive support
- Date calculation functionality
- Looping and iteration support
- User-defined function storage in separate files
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- Temperature unit support (Celsius, Fahrenheit)
- Logarithmic and non-proportional unit definitions
- Multiple parametric plots simultaneously
- Landscape mode optimization
- Tabular data and multi-row markdown table support
- Dark mode (now implemented)
- Subscription model option for ongoing development
- Decimal place formatting control
- Charting and financial functions
- Better document management interface
Things 3
Reported bugs
2 issues- Sync issues between devices
- Occasional crashes or freezes
Requested features
5 requests- Ability to collapse headings and projects
- Location-based reminders
- Two-way calendar sync
- Shared task lists
- Customizable alert sounds
In-app purchases
Calca
- 6-Month Optional Patronage$4.99
- 12-Month Optional Patronage$7.99
Things 3
No in-app purchases









