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Variables · Percentages · Live currencies

A notepad that calculates as you type.

Build quotes and budgets with variables, percentages and live currencies. Change one input; the answers update.

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One free note. Unlimited calculations. Lifetime adds unlimited notes and sync.

  • macOS
  • Windows
  • Linux
  • Android
  • Web
Watch the 22-second demo · with sound. Change 12 hours to 18: the total with 21% tax goes from 822.80 to 1,185.80, and the USD-to-EUR conversion updates too. Recorded in the web app on macOS. Exchange rates shown are from the recording.

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  • Free forever plan
  • Instant results as you type
  • No ads
  • Sync with Lifetime
  • 200+ live currencies

See it calculate

See what you can calculate

From a quick percentage to a reusable project note, the working and the answer stay side by side.

  • Build a quote with named values

    Use readable names with spaces, then change one value and let the whole note recalculate.

    Named variables
    NoteResult
    hours = 12 12
    hourly rate = 50 50
    design fee = 80 80
    subtotal = hours * hourly rate + design fee 680

  • Write percentages naturally

    Calculate a share, add tax, or take a discount in the same words you would say aloud.

    Quick calculations
    NoteResult
    10% of 200 20
    20% of 150 30
    200 + 15% 230
    10% off 200 180

  • Convert units in place

    Keep the question and its converted result together, including angles and areas.

    Unit conversions
    NoteResult
    60 degrees in rad 1.05 rad
    10 square km in square mile 3.86 mi²
    1 cm + 100 mm 110 mm
    10 W in kW 0.01 kW

  • Check live currencies

    Convert dollars, euros and Bitcoin directly in the note, then keep working with the answers.

    Currency conversion
    NoteResult
    $100 in euro €86.04
    100 EUR in USD $116.23
    0.01 BTC in USD $500.00
    Illustrative results; the app uses live exchange rates.

  • Plan with dates and durations

    Measure date gaps, move deadlines, and add durations without leaving the note.

    Dates and durations
    NoteResult
    12/25/2026 - 12/01/2026 24 days
    12/25/2026 + 7 days 01/01/2027
    1 hour + 30 minutes 90 minutes

  • Work across scales

    Move between data, energy, and other measurement scales without looking up factors.

    Scale conversions
    NoteResult
    2 GB in MB 2,000 MB
    3 kcal in cal 3,000 cal
    10k dyne in N 0.10 N

  • Switch number bases

    Convert and calculate with hexadecimal, binary, octal, and decimal values.

    Programmer math
    NoteResult
    255 in hex FF
    255 in binary 11111111
    0xFF + 0x10 271
    0b11010 in decimal 26

  • One tab is free. Write unlimited calculations in it. Lifetime adds unlimited tabs, with sync across signed-in devices.

  • Use it where you work. Native apps for macOS, Windows, Linux, and Android, plus the web app. iPhone is coming soon.

  • 200+ live currencies. Rates refresh every hour. Keyboard shortcuts and dark and light themes keep daily work comfortable.

How it works

From blank page to answer in seconds

No formulas. No cells. No menus. Just write — and let the calculator keep up with you.

  1. 01

    Open a fresh note

    Launch Notes Calculator on any device. No accounts, no setup — just a blinking cursor.

  2. 02

    Type math like you would write it

    Mix numbers, units, and currencies. Use variables to name values and reference them anywhere.

  3. 03

    Get answers as you type

    Results appear instantly on the right. Reference variables, change one number, and watch totals update in real time.

Built for the way you work

One calculator. Every kind of math.

From freelance quotes to student homework, Notes Calculator adapts to whatever you're working on.

Freelancers

Estimate quotes, work out hourly rates, and check invoice totals before sending.

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Students

Solve homework with variables, calculate GPAs, and convert units without leaving your notes.

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Travelers

Convert between 200+ currencies in real time. Plan trips with mixed-currency budgets.

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Developers

Convert hex, decimal, binary, and bytes. Sketch out math next to your code.

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Engineers

Convert drawings between mm and inches, sanity-check °C/°F, and stack tolerances inline.

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Business owners

Track profit margins, model budgets, and forecast compound growth in plain English.

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Everyday math

Tips, splits, percentages, and quick mental-math shortcuts — all in one place.

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Downloads

Pick your platform — get going in seconds

Native apps for desktop and Android. Or skip the install and use the web app.

macOS Universal · Apple Silicon & Intel
Windows Microsoft Store
Linux .deb installer
Linux .rpm installer
Android Google Play
Web App Runs in any browser

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Notes Calculator adds labels and inline notes that the math ignores, conditionals inside expressions, and export to Markdown, plain text, CSV, or PDF.

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Big Numbers: Type Millions to Nonillions in a Plain-Text Calculator

Big numbers get unwieldy fast: 1,000,000,000,000 or 1 quadrillion? Notes Calculator lets you type 1M or 1Q and calculate at scale without counting zeros.

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Stop fighting your calculator.

Notes Calculator is free to use, fast to learn, and ready in your browser. Upgrade later if you want sync and unlimited tabs.

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