Write it down.
It adds up.

A notepad that calculates as you type. Currencies, units, dates and time zones, answered instantly.

Try it free Buy for $14.99

Free for 7 days · No account, no card

Try me

160+ currencies

Crypto

150+ units

Time zones

Terminal

Works offline

Private by design

Write it the way
you would say it

Splitting the bill, checking a quote, planning a trip. Write a line and the answer appears beside it.

Every currency. Always current.

More than 160 currencies and the major cryptos, with rates that refresh on their own. Mix dollars, euros and pounds in one line.

Any unit. Any time zone.

Kilometers to miles, Fahrenheit to Celsius. Ask what 3pm is in Tokyo, or how many days are left until the deadline.

Change one number. Everything follows.

Name a value or point to a line with L3. Fix the price at the top, and every line below updates on its own.

Split the bill by name.

Put @names after what each person had and type split. Ratio shows who owes what, ready to paste into the group chat.

Notch

A calculator in the notch

Opens when the pointer rests on the notch
Or press ⌥⇧Space from any app
Pin any line to the menu bar

Widgets

Your numbers, on the desktop

“Days until payday” as a ring on your desktop
The rate you check every day, with its last days as a chart
What you pay each month, split by service

Money

Salary, mortgage and pension, worked out

Take-home pay for Romania, Germany, the UK and the US
Loans, savings, ROI and your FIRE number
Invoices, VAT and working days

See the money syntax

Math

Homework, solved

Equations, integrals and derivatives
Exact answers like 2√2
Constants, units, statistics and primes built in

Read the syntax

Developers

Subnets, hashes and the cloud bill

CIDR ranges, masks and subnets
Base64, SHA-256 and UUIDs
Hex, binary and bit shifts

MCP

Claude asks, Ratio works it out

Works with Claude, Cursor and VS Code
Today's exchange rates, stocks and working days
Set up with one command

Set it up

Split 184 euros between 3 people, in dollars.

ratio calculate 184 eur / 3 in usd $68.55

That's $68.55 each, at today's rate of 1 EUR = 1.12 USD.

Same dinner bill.
Only one shows its work.

Drag the handle to compare a regular calculator with Ratio.

Calculator

One number, no history

Ratio

Dinner

# dinner for 4

bill = 120 eur€120

tip = 10%10%

total = bill + tip€132

each = total / 4€33

each in usd$36.96

Every step kept, change any line

Private by design

Your numbers stay yours.

Ratio does every calculation on your computer. Nothing you type is sent anywhere, and it works offline.

Nothing leaves your computer.

Buy it once.
It's yours.

One version, with everything included. Use it free for 7 days. If you love it, buy it once and keep it for good.

1 computer

For your Mac or PC.

$14.99once

Buy for $14.99

Updates included
14-day refund

2 computersPopular

$12.50 each. Your laptop and your desktop.

$24.99once

Buy for $24.99

Any mix of Mac, Windows, Linux
Move it between computers anytime

3 computersSave 22%

$11.66 each. Enough for the whole household.

$34.99once

Buy for $34.99

Any mix of Mac, Windows, Linux
Move it between computers anytime

Everything included, on every plan

160+ currencies
Crypto
150+ units
Time zones
Live countdowns
Line references
Lists and plots
Salary and loans
Ask AI on your Mac
Calculator in the notch
In your Terminal
MCP for Claude
14 themes
iCloud sync
Works offline

“Ratio makes everyday math feel effortless: just write things down and get clear, live answers instantly—no spreadsheets, no fuss. It handles currencies, units, dates, and more, all in one simple, private notepad. Loved it so much went back and got a couple more copies.”

Terry CarsonDeveloper

“I like how Ratio makes everyday calculations feel as simple as writing notes, especially the instant answers, live currency conversions, and ability to reuse results without opening a spreadsheet.”

AlaladeRatio user

Student or teacher? Half price. Write to us from your school email and we'll send you a code.

Questions

Ask AI about Ratio: ChatGPT Claude Perplexity

What is Ratio?

Ratio is a notepad calculator for Mac, Windows and Linux. You type calculations as plain text, like "dinner 84 eur / 3", and the answer appears beside each line as you type. It understands currencies, crypto, units, dates and time zones.

Does Ratio run on Windows and Linux?

Yes. Ratio runs on Windows 10 and 11 (64-bit) and on 64-bit Linux (Ubuntu 22.04 or newer, Debian, Fedora and others, as an AppImage or a .deb). It uses the same engine as on the Mac, so every line gives the same answer. The trial and the license work the same way everywhere, and a 2- or 3-computer license can mix a Mac, a PC and a Linux machine. iCloud sync, Liquid Glass and the Terminal command are Mac only for now.

Can Claude or other AI assistants use Ratio?

Yes, on the Mac. Ratio comes with an MCP server, so Claude, Cursor and VS Code can work out currencies, stock prices, units, dates and VAT with Ratio instead of guessing. How to set it up

Does Ratio work offline?

Yes. Every calculation happens on your computer. Exchange rates need a connection to refresh, and while you're offline, Ratio uses the last rates it downloaded.

Do I really pay only once?

Yes. You pay once, and that's it. Updates are included.

Is there a free trial?

Yes. Ratio is free for 7 days, with no account and no card. If you buy it and it isn't for you, email us within 14 days and we'll refund it.

How do I move my license to another computer?

In the app, open Ratio Pro and click “Deactivate this Mac” (or “Deactivate this PC” on Windows and Linux). Then enter the same key on the new computer, whether it's a Mac, a PC or a Linux machine.

See how it
all adds up

Try it free for 7 days. No account needed.

Download for Mac

Write it down.It adds up.

Write it the wayyou would say it