Free time tools: dates, world clock and timers

How to, step by step

• Why online timers drift in background tabs

  Browsers slow down pages in background tabs, so a timer that counts ticks loses time. How the KeepSimp Timer keeps exact time instead.

• Stopwatch laps vs splits, and how precise timing is

  What the lap and split buttons record, how to read fastest and slowest laps, and why your reaction time matters more than hundredths.

• The Pomodoro Technique: lengths, breaks and rules

  The Pomodoro Technique as Francesco Cirillo wrote it: 25 minutes of work, short breaks, a long break after four, and why an interrupted one is void.

• Visual timer for classrooms and kids, free

  Why a visual timer helps children see time passing, how to show one full screen on a board, and how to choose a gentle sound at the end.

• Tabata timer: 20 seconds on, 10 off, 8 rounds

  What a Tabata is, where the 20 and 10 seconds come from, and how to set your own rounds of work and rest on an interval timer with pips.

• How to set a countdown timer online

  How to set a countdown for any length up to a day, add a minute while it runs, choose its sound, and know it ended even if you looked away.

• 5 minute timer: what to do in five minutes

  A five-minute timer for a short break, a stretch or a quick task, with a sound at the end and a minute added at a press. Ready to start in your browser.

• 10 minute timer: quick tasks, quizzes and calm

  A ten-minute timer for a quick tidy, a short meditation or a timed quiz, with a sound at the end. Ready to start in your browser, nothing sent.

• 15 minute timer for study sprints and lessons

  A fifteen-minute timer for a study sprint or a classroom activity, shown as digits or a ring that empties, with a sound at the end. Ready to start.

• How long should a power nap be? A 20 minute timer

  The Sleep Foundation puts the ideal nap at 20 to 30 minutes. A twenty-minute timer for a nap or a short workout, with a gentle bell at the end.

• 30 minute timer for workouts, meetings and reading

  A thirty-minute timer for a workout, a focused meeting or reading time, with the time left in the tab's title and a sound at the end. Ready to start.

• 1 hour timer for study, exams and baking

  A one-hour timer for a study block, a practice exam paper or something in the oven, keeping exact time in the background. Ready to start, nothing sent.

• How to count days between two dates (with or without the end)

  Counting days between dates gives a different answer depending on whether the last day counts. How the Date calculator counts, in days, weeks and months.

• What is 31 January plus one month? Adding months to dates

  Adding a month to 31 January cannot land on 31 February. How the Date calculator adds days, weeks, months and years, and what it does at a month's end.

• How to calculate exact age in years, months and days

  Age in years, months and days, counted from the last birthday, with the rule for a 29 February birthday in common years and a few fun facts.

• How to count business days between dates, with holidays

  Working days leave out weekend days and public holidays, which differ by country and region. How the Date calculator counts them for 250 countries.

• What week number is it? ISO and US week numbers

  ISO weeks start on Monday and week 1 holds the year's first Thursday, so early January can be week 52 or 53. How it differs from the US way.

• How many days until a date? A countdown you can share

  Type an event or a date and see the days left, a live countdown and a calendar entry, with the rule each holiday's date follows. Nothing is sent.

• How many sleeps until Christmas? The countdown explained

  The days, weeks and hours left until Christmas Day on 25 December, with a live countdown you can share and add to your calendar.

• How many days are left in the year?

  The days, weeks and hours until 1 January, with a live countdown to midnight, a link to share and a calendar entry. Worked out in your browser.

• When is Halloween this year, and how long is left?

  The days and weeks until Halloween on 31 October, with a live countdown, a link to share and a calendar entry. Nothing you type is sent.

• When is Diwali this year? The date and the countdown

  The days until Diwali, whose date follows the Hindu lunar calendar, from python-holidays' list for India, with a live countdown and a calendar entry.

• How time zones and daylight saving time work

  Why some places are half an hour apart, why the gap between two cities changes twice a year, and how the World clock shows each place's time and daylight.

• How to convert time zones: 3pm EST to IST and others

  Type a time and places to convert it, with the day it falls on there and what abbreviations like EST, IST and CST were taken to mean.

• How to find a good meeting time across time zones

  See each place's working, waking and sleeping hours side by side, with its own weekend, and the best time said in words. Share it as a link or a calendar file.

• Is EST one hour ahead of CST?

  US Central Time is one hour behind Eastern Time all year, since both change their clocks on the same days. Convert a CST time to EST, with the day.

• How many hours behind UTC is Eastern Time?

  New York is five hours behind UTC in winter and four in summer. Convert a UTC time to Eastern Time with the day, and see when the gap changes.

• What time is it in India when it is 9am in New York?

  India is 10½ hours ahead of New York in winter and 9½ in summer, since India keeps one time all year. Convert EST to IST with the day it lands on.

• How far behind London is New York?

  New York is five hours behind GMT, and London keeps BST in summer. Convert GMT or London time to Eastern Time, with the weeks when the gap is four hours.