Money, dates, units, totals, charts, and an assistant that writes the page for you. No formulas, no buttons, no grid. Every example below runs in the editor above, so try one.
Write in plain words, one line at a time. Every line shows its result on the right and updates the moment you change a number. Name a value once and reuse it anywhere below.
Mix dollars, euros, yen and more. Convert with "in EUR" using the daily European Central Bank rates, no setup needed. Plain numbers join in and take the right currency automatically.
Measure the gap between two dates, count down to a deadline, or do clock and duration math. Write it the way you say it: "next friday", "days until dec 25", "9:45am + 3h 15min".
Distance, time, speed, data, weight and more. Convert with "to" or "in", and OtterCalc keeps the units straight, so incompatible math is a clear error instead of a wrong answer.
Type "subtotal" or "total" to sum a section, or "pie", "bar" or "line" to turn the values above into a chart, right inside your notes. It redraws as you edit.
Describe the problem in words and Otto writes the page: every line is a live calculation the engine has checked, so you can edit any number or drag it after. Otto asks back when only you know the answer, and never invents your salary.
Yes. OtterCalc is free to use, and no account is required.
No. There are no accounts. Start typing right away and, when you want, save a calculation to get a shareable link.
Your draft stays in your browser and never leaves it until you choose to save. Saved calculations are stored so their link can reproduce them. Read the privacy page.
A calculator forgets the last step and has no words; a spreadsheet needs a grid and formulas. OtterCalc keeps the whole train of thought in plain sentences you can read back, edit, and share, so it fits the quick, one-off math you do every day.