1. Rules come from official sources
Every calculator is built from the rules and guidance published by the authority that applies them: the European Commission (Schengen), USCIS and the IRS (United States), the Home Office and HMRC (United Kingdom), IRCC (Canada), the Department of Home Affairs (Australia), and Immigration New Zealand and the Department of Internal Affairs (New Zealand). Each page lists the official sources it relies on, so you can check them yourself.
Where official guidance is unclear, or sources disagree, we say so on the page and choose the more cautious reading. For example, the British citizenship calculator asks you to confirm you were in the UK on two possible start dates, because guidance differs on which one applies.
2. Days are counted the way each authority counts them
Rules differ on whether the day you leave and the day you arrive count, and whether limits apply per calendar year or in any rolling period. Each calculator uses the method of the authority behind it:
- Stays (Schengen, the US substantial presence test, the 183-day counter): entry and exit days both count as days present.
- Absences (US, UK, Canadian, Australian and New Zealand residence rules): only full days abroad count. Departure and return days count as days in the country.
- UK statutory residence test: a day counts if you are in the UK at midnight.
- Rolling limits ("any 12 months", "any 180 days") are checked for every possible window, day by day, not just calendar years.
See how each country counts travel days for a side-by-side comparison.
3. The maths is tested
The counting engine behind all 16 calculators is a set of plain functions with automated tests. The tests cover exact limit boundaries (such as 180 days allowed but 181 not), leap years, trips that cross New Year, overlapping trips, and worked examples checked by hand. The rolling-window engine is also checked against a brute-force count on randomly generated travel patterns. Every change to the site must pass these tests before it is published.
4. Rules are reviewed and dated
Each calculator shows the date its rules were last checked against official sources (currently 29 September 2026). When a rule changes, or a significant change is announced but not yet in force (such as the UK's proposed "earned settlement" reforms), we update the page and say clearly which rules the calculator applies.
5. Your data stays with you
The calculators run entirely in your browser. The dates you enter are saved only on your device and are never sent to us. See our privacy policy.
6. What the calculators don't do
They estimate whether you meet the time-based parts of a rule from the dates you enter. They don't assess discretion, exceptions, good character, language tests, tax treaties or anything else outside the dates. They are not legal or tax advice. For a decision that matters, check the official guidance or speak to a qualified adviser.
7. Corrections
If you think a calculation or a rule is wrong, please email hello@abroaddays.com with the page and, if you can, the dates you used (the "Export CSV" button helps). We review every report, fix confirmed errors promptly, and update the "rules checked" date when we do.