Six months is not 180 days

Plenty of tools quietly convert "6 months" into "180 days" because days are easier to compute with. That conversion is wrong every single time, and it is wrong by up to four days.

Why the numbers differ

A calendar month is not 30 days. Six consecutive calendar months contain between 181 and 184 days, depending on which months they are and whether a February falls inside.

Worked examples:

Treating any of those as 180 days makes you leave early — annoying but safe. The danger is the reverse: a tool that tells you a six-month permission is "180 days" and then counts 180 days from a later entry date can push your calculated departure past the real one.

Which permissions are actually in months

The UK Standard Visitor is the clearest case. A visitor may usually stay for up to 6 months from the date of entry. The source expresses it as a calendar period, so that is how DAYOZA stores it — in months, not flattened into days.

Canada's visitor allowance is likewise usually 6 months from the day of entry.

Australia's eVisitor works the same way: 3 months per entry, not 90 days.

How DAYOZA handles it

Rules keep whichever unit their source actually uses. A rule written in months is computed in months; a rule written in days is computed in days. Nothing is silently converted, because the conversion is the bug.

You can see this on the Visa Stay Calculator: enter a month-based allowance and the result lands on the calendar date the period actually ends, not on entry-plus-180.

The caveat that matters more than the arithmetic

"Up to six months" is a maximum, not an entitlement. A shorter period may be granted at the border, and where a specific date has been written into your permission, that date governs — not the six months, and not anything a calculator tells you. Always work from the date you were actually given.

Sources: GOV.UK — Visit the UK as a Standard Visitor; IRCC — How long can I stay in Canada?.