What is a notepad calculator?
Written by Adrian Viziteu, who makes Ratio, one of the apps below.
A notepad calculator is a text editor that does maths. You write each step of a calculation as a line of text, in words if you like, and the result appears beside the line as you type. Every line stays editable, so changing one number updates everything that depends on it.
What it looks like
| # Weekend in Lisbon | |
| flights = 2 * 189 usd | $378 |
| hotel = 3 * 92 eur | €276 |
| sum in usd | $688.14 |
| prev / 2 | $344.07 |
Results above were calculated on 18 October 2026 and follow the exchange rate.
How it differs from other calculators
- A keypad calculator shows one number at a time. Once you press a key, the steps are gone.
- A spreadsheet keeps the steps, but in cells and formulas you have to set up first.
- A notepad calculator keeps the steps as readable text, with names instead of cell addresses, and needs no setup.
What it is good for
Short calculations with a few connected steps: a budget, a quote or invoice, splitting a bill, a trip in another currency, a deadline in working days, a unit conversion in the middle of a recipe. For big tables of data, a spreadsheet is still the better tool (see Ratio vs a spreadsheet).
What most notepad calculators understand
- Arithmetic and percentages in words:
20% of 150,150 + 20% - Variables and references to earlier lines:
price = 1200,prev / 4,sum - Units and currencies:
5 km in mi,100 usd in eur - Dates and times:
today + 2 weeks,3pm London in Tokyo
Notepad calculators you can use
Soulver (Mac, iPhone, iPad) made the idea popular on the Mac. Numi (Mac, Windows, Linux), Calca (Mac, iPhone, iPad, Windows) and Ratio (Mac, Windows, Linux) work the same way. They differ in price, platforms and what they understand. The comparison of notepad calculators lists them side by side.
Try Ratio free for 7 days · $9.99 once, on Mac, Windows and Linux
Questions
What is a notepad calculator? A text editor that calculates. You write each step as a line, in plain words, and the answer appears next to the line as you type. Lines stay editable, so a change updates everything below.
Is a notepad calculator the same as a text calculator? Yes. Notepad calculator, text calculator and natural-language calculator all describe the same kind of app.
Which notepad calculators are there? The best known are Soulver, Numi, Calca and Ratio. Ratio runs on Mac, Windows and Linux.