About this calculator

Why does this calculator exist?

USCIS used to publish its own early filing calculator. It no longer works — the page returns a not-found error under an archived-content banner, yet it still shows up near the top of search results for people looking for exactly this tool. The alternatives that do work either charge a monthly subscription and require installing a phone app, or are generic add-and-subtract-days calculators that know nothing about how USCIS actually counts a trip.

This site is a free replacement built directly from the USCIS Policy Manual and the Code of Federal Regulations, not from a generic date calculator repurposed for immigration. Every rule it applies is listed, with its source, on the how it works page.

Who built this?

N400 Calculator is built and maintained by Tejas Kalpande, an independent software developer. It is not affiliated with USCIS or the US government, and it is not a law firm — see the terms page for what that means for you.

Why is it free?

Filing Form N-400 already costs several hundred dollars, and a wrong filing date can cost that fee again if the application gets rejected. Charging people to find out whether they're eligible to spend that money didn't seem right, so there's no subscription, no paywall, and no account to create. If the site carries ads in the future, they will not change what the calculator tells you or require reading past them to use it.

How is it built?

The calculator runs entirely in your browser. There is no server processing your dates and no database storing them — see the privacy page for the details. The source code implements the rules listed on the how it works page and nothing beyond them.