Support
Sumico for Chrome and for Windows. Last updated 23 September 2026.
A person reads every message. Write to mak.golub@gmail.com and say which version you are on, Chrome or Windows, and what you typed when it went wrong. A copy of the line is worth more than a description of it.
Is Sumico free?
Yes. There is no account, no sign-in and no paid tier.
Where does it run?
In the Chrome side panel as an extension, and on Windows as a desktop app. Both run the same calculation engine, so a document behaves the same in either.
How do I open it?
Click the Sumico icon in the Chrome toolbar and the side panel opens. If the icon is hidden, open the puzzle-piece menu and pin it.
What can Sumico calculate?
Percentages in several plain English forms, units of length, mass, volume, data, speed, temperature and angle with SI prefixes, 160 fiat currencies and around 20 crypto tickers, dates, durations and time zones, variables, line references such as prev, sum and average, and the usual functions and number bases.
What can Sumico not do?
It does not sync between devices, it does not read the page you are on, and it does not pick numbers out of a web page. In the extension it does not import or export files; that one is a desktop feature.
Does it work offline?
Yes. Calculation is entirely local. Exchange rates are cached, and a dated snapshot of 186 rates ships inside the extension, so currency lines still resolve with no connection. When a rate is older than Sumico considers current, it marks it as stale rather than pretending otherwise.
A rate looks wrong or out of date.
Open Preferences and press Refresh rates now. If the marker stays, the source is unreachable and Sumico is falling back to the snapshot on purpose. You can switch the fiat source between ExchangeRate-API and the European Central Bank there as well.
Where are my calculations stored?
In this browser, in IndexedDB, on your own machine. Nothing is uploaded and nothing is shared between devices. See the privacy policy for what is stored and what leaves the browser.
My documents disappeared.
Sumico stores them in the browser profile it runs in, so clearing browser data for the extension, or removing and reinstalling it, removes them with it. There is no copy on a server to restore from. The desktop app can export a document to a file; the extension cannot.
Does Sumico use AI?
No. There is no model, no API key and no prompt anywhere in the calculation path.
A line will not calculate.
Sumico answers in plain English, so the message on the line is the actual reason: an unknown unit, an unknown name, a missing bracket. Unit names have to be spelled out in full, and a mixed expression like 5 feet 3 inches in cm works, while an abbreviated one does not.
I want to report a bug or ask for a feature.
Same address: mak.golub@gmail.com. Bug reports that include the exact line and the expected answer get fixed first, because they turn straight into a test.