Date arithmetic looks simple, but a calendar is a fiddly thing. Months don’t all have the same number of days, leap years bend February, and what counts as a “working day” depends on which part of the United Kingdom you live in. This page explains the rules our calculators use so you know exactly what you’re reading.
The clock we use
Every countdown on Until Then is calculated against the UK time zone, Europe/London. That means it follows British Summer Time in the summer and Greenwich Mean Time in the winter, and it switches automatically on the dates set by Parliament. If you’re reading the site from another country, your countdown will still be correct for the date in the UK; it may differ by a few hours from your local clock.
The countdown timers on each page update live in your browser. The headline number (“There are 365 days until…”) is calculated server-side when the page is built, and refreshed regularly so it stays accurate as days tick over.
Days, weeks and months
- Days are full calendar days. A countdown of “5 days” means five midnights between now and the target date.
- Weeks are seven-day weeks. We round to the nearest whole week and show the leftover days separately, so “52 weeks and 1 day” is more useful than “52.14 weeks”.
- Fortnights are pairs of weeks — the way many UK pay packets and rotas are set out. We round in the same way as weeks.
- Months are approximate. Because months are different lengths, we calculate a “months remaining” figure by counting whole calendar months between the two dates. If a target date sits in the middle of a month, we round to the nearest whole month.
- Sleeps are simply nights between today and the target. They’re handy for counting down to Christmas with children.
Working days
By “working day” we mean Monday to Friday, excluding the standard public holidays. We use the official England and Wales bank holiday list as published by the UK Government at gov.uk/bank-holidays.
Bank holidays differ in Scotland and Northern Ireland. Where the difference matters — for example, the second Monday in July in Northern Ireland, or 2 January in Scotland — we add a note next to the calculator so you can see at a glance whether your local calendar is different.
Weekends
For our calculators, a weekend is Saturday and Sunday. The “weekends remaining” count is the number of complete Saturday-Sunday pairs between today and the target date. Where the target date itself falls on a Saturday or Sunday, we include that day in the count of weekend days remaining but treat the weekend pair as ending on the target.
Leap years and February 29th
Leap years follow the standard Gregorian rule used in the UK and most of the world: a year is a leap year if it’s divisible by 4, except for centuries, except again for centuries divisible by 400. So 2000 was a leap year, 1900 wasn’t, 2100 won’t be, and 2400 will be.
Our “until February 29th” page only shows a useful figure in leap years. In non-leap years it returns the next leap-year February 29th, with a note explaining why.
The UK financial year
The UK personal tax year and the public sector financial year both run from 6 April to 5 April. Where we count “weeks left in the financial year”, we mean weeks until 5 April of the current tax year.
If you need the corporate financial year for a specific company, you’ll need that company’s accounts — companies in the UK can choose their own year-end and many use a calendar year, March year-end, or another date entirely.
Accuracy and corrections
We test the calculators against a fixed set of reference dates, including known leap years and bank holiday weekends, and we re-test before each calendar-year rollover. If you spot a date that doesn’t look right — a day-of-the-week that’s wrong, a missing holiday, or a calendar that doesn’t add up — please email us at hello@untilthen.co.uk and quote the URL of the page. We’ll usually fix it within a working day.
What we don’t do
For clarity: Until Then does not run a forum, take user submissions, host downloads, sell anything directly, or ask for personal information. The site has one job — counting down to dates — and we keep it that way deliberately.