A calculator that works like a notepad. Type what you're thinking — every line gets a live answer in the right column. No buttons, no formula syntax, just text.
# Trip to Lisbon
flights $420
hotel $95 * 4 nights
food 30€ a day * 4 days and museums 25€
total → $1,066.97
5 inches in cm → 12.7 cm
100 km/h in mph → 62.14 mph
$2000 in rubles → 144,060 ₽
20% off 1500 → 1,200
today + 6 weeks → 22 July 2026
time in Tokyo → 14:25
Works in English and Russian at the same time: 5 метров в см, 20$ в евро,
сумма — no language switching.
Grab the latest Summarum_*_x64-setup.exe from Releases,
run it, done. The whole app is about 2 MB.
Requirements:
- Windows 10 (1803+) or Windows 11, 64-bit.
- WebView2 Runtime — already part of Windows 11 and most updated Windows 10 systems; if it's missing, the installer downloads it automatically.
- Internet connection is only needed for live currency rates — everything else works offline (rates fall back to a cached/bundled snapshot).
Plain math — 2 + 2, 8 / (45 - 20%), parentheses, ^, sqrt, sin,
factorials. Decimal-exact: 0.1 + 0.2 is 0.3, not 0.30000000000000004.
Words as operators — 12 plus 4, 20 divided by 4, 5 и 3. Text around
the math is ignored, so spent 20 on pizza and 5 on coffee just gives 25.
Units — length, weight, volume, area, temperature, time, angles, data
(1 GiB in MB), CSS px/em, speed, pressure, energy, power, frequency, fuel:
6 feet in meters 1 atm in mmHg 8 л/100км in mpg
2 hours 30 min in min 150 hp in kW 32 px in em
Money — ~150 currencies and the top-20 crypto with live rates
(refreshed hourly, cached for offline). $100 + 20%, 5 eth in USD,
9800 рублей в долларах.
Percents the human way — 20% of 80, 20% off 1500, 5 as a % of 25,
20% of what is 30.
Dates and time — today + 2 weeks, tomorrow - today, time in New York,
now in unix, 1750000000 as date.
Programmer stuff — 0xFF & 0x0F, 1 << 4, 255 in hex, in binary,
plus in fraction (0.75 → 3/4) and in roman (2026 → MMXXVI).
Sheets that calculate — variables (rent = $500), running totals
(sum, avg, prev), # headers, // comments. The status bar always shows
the sheet total; select a few lines to see just their sum.
- Ctrl+Alt+N (configurable — the settings field records keys you press) shows/hides the window from anywhere. Closing hides to tray.
- Click a result to copy it. Copying a line copies it with the answer
(
rent * 3 = $1,500). Ctrl+Shift+C copies the whole sheet with answers. - Drag the divider to resize the results column.
- Drop a
.numi,.sum,.txtor.mdfile into the window to open it as a sheet. - Backups are automatic: a daily snapshot of all sheets (last 14 kept), and deleted sheets sit in a bin for 14 days (configurable) — restore one by dragging the file back in. Settings → Backups opens the folder.
- Data folder is configurable — point it at OneDrive/Dropbox and your sheets follow you between machines.
- Light/dark theme, en/ru interface, configurable precision and separators.
Note: extensions run as trusted local scripts with access to your files. Only load code you wrote or fully trust.
Drop a .js file into the extensions folder (Settings → Extensions folder)
and restart. The API is compatible with Numi extensions:
numi.setVariable("vat", { double: 20 });
numi.addUnit({ id: "floor", phrases: "floor,floors", baseUnitId: "meter",
format: "fl", ratio: 3 });
numi.addFunction({ id: "hyp", phrases: "hyp" },
(v) => ({ double: Math.hypot(v[0].double, v[1].double) }));Then 5 floors in meters → 15 m and hyp(3; 4) → 5.
Open an issue. A line of text and what you expected is enough.
Engine internals, project layout and how to add units/currencies: see ARCHITECTURE.md.
npm install
npm test # engine tests
npm run tauri dev # run the app
npm run tauri build # build the installerTo build from source you need:
- Node.js 22.6 or newer (
npm run iconsrelies on Node's built-in TypeScript support) - Rust (stable, MSVC toolchain)
- Visual Studio Build Tools with the "Desktop development with C++" workload (the MSVC linker)
- See the Tauri prerequisites page if anything refuses to compile
Stack: Tauri 2 + TypeScript + CodeMirror 6.
Inspired by the excellent Numi by Dmitry Nikolaev — if you're on macOS, buy it. Summarum is an independent project, built from scratch for Windows.