Ratio

Ratio is a notepad calculator for desktop operating systems that computes equations, currency conversions, and unit transformations as text is typed.

Ratio is a notepad calculator designed for Mac, Windows, and Linux that executes mathematical operations as users type them in plain text. It automatically handles conversions for over 160 currencies, various units of measurement, dates, and time zones. Users can reference specific lines to create dynamic calculations that update when initial values change. The software supports financial tasks like salary, mortgage, and VAT estimation, alongside technical functions for subnets and file hashes. All calculations occur locally on the device to ensure privacy, and the software functions offline between data refreshes. It integrates with development tools like Claude, Cursor, and VS Code via an MCP server.

Ratio at a glance

Best for: Software engineer
Runs on: macOS, Windows, Linux
Pricing: $14.99 one-time purchase; includes updates and 7-day free trial.
Released: November 2026
Category: AI productivity tool
Website: useratio.app

Key features

Live currency and cryptocurrency conversion
Automatic unit and time zone calculation
Line referencing for dynamic updates
Local, private calculation engine
Integration with Claude, Cursor, and VS Code
Financial tools for VAT, mortgage, and salary calculation
Technical function support including UUIDs and hex conversion

Use it for

Splitting expenses and calculating debts between people
Planning travel budgets with live exchange rates
Solving academic equations and statistical problems
Managing IT tasks like CIDR calculations and file hashing

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