Date & Time Tools Overview

Dates and times seem easy until you really have to work with them. A meeting is set in someone else's time zone. A server log shows a long number instead of a date. A form asks for your exact age in days. Each of these is a small problem, but they show up all the time, and solving them usually means opening a new site or writing a quick script.

This page keeps the five most common jobs under one set of tabs. The first tab is a live clock with your time zone, UTC offset, current Unix timestamp, ISO week and day of the year. The other four tabs turn a timestamp into a date (and back), work out an exact age, measure the gap between two dates, and convert a time from one zone to another. There is no sign-up and no upload. Your browser's own clock and time zone data do all the work.

What Is a Unix Timestamp?

A Unix timestamp is one number that marks one moment: how many seconds have passed since 00:00:00 UTC on 1 January 1970, a point known as the Unix epoch. Early Unix developers picked it because it makes time maths trivial. Subtract one timestamp from another and the answer is a duration, with no calendar needed.

It also removes confusion. A written date like 03/04/2026 means 3 April to some people and 4 March to others, and a clock time means little without a zone. A timestamp has neither problem, because it is the same number everywhere in the world at the same instant. That is why servers, databases and log files store time this way.

Timestamps are usually in seconds (about ten digits today). JavaScript and some other systems use milliseconds (thirteen digits). The converter here reads the size of the number and picks the right unit by itself. For example, 1700000000 is 14 November 2023, 22:13:20 UTC. The result shows the moment in UTC, in your local time and in ISO 8601 form.

How Time Zones and UTC Work

UTC (Coordinated Universal Time) is the reference that every other clock is measured against. It is kept by atomic clocks and never changes for daylight saving. Every zone is described as an offset from it: India is UTC+05:30 all year, while New York is UTC−05:00 in winter and UTC−04:00 in summer. Some places even use 45-minute offsets, so code that assumes whole hours will break.

A time zone is more than an offset. It is a named region with its own history and rules, such as Asia/Kolkata or Europe/London, and the offset is simply what those rules give on a particular date. Governments can change those rules at short notice, so the result cannot be calculated from a formula. It has to be looked up in a table, the IANA time zone database. Your browser carries a copy, and this tool asks the browser to do the conversion. As your browser updates, the answers stay current.

What Is ISO 8601?

ISO 8601 is the international way to write dates and times so they cannot be misread. The biggest unit comes first: year, month, day, then a T, then hours, minutes and seconds, then Z for UTC or an offset like +05:30. So 16 October 2026 at 2:30 pm in India is 2026-10-16T14:30:00+05:30. Because the biggest unit leads, sorting such strings alphabetically also sorts them by time, which is handy for filenames and databases.

A few related forms are worth knowing. 2026-W42 means week 42 of 2026. A bare date like 2026-10-16 is valid on its own. A duration starts with P, so P3D is three days and P1Y2M10D is one year, two months and ten days. The trailing Z simply means the time is in UTC.

Date & Time Tools Features

• Live clock. Updates every second, with a 12-hour and 24-hour switch and the full written date.
• Handy details. Time zone name, UTC offset, current Unix timestamp, ISO week, day of year, days left in the year, quarter and leap year check.
• Copy timestamp. One tap copies the current Unix timestamp to your clipboard.
• Timestamp converter, both ways. Paste seconds or milliseconds to get a date, or pick a date and time to get the timestamp. Results show UTC, local time and ISO 8601.
• Automatic unit detection. The tool decides between seconds and milliseconds from the number's length.
• Exact age calculator. Years, months and days, plus total months, weeks, days and hours, the weekday of birth and days until the next birthday.
• Date difference. Years, months and days between two dates, with total days, weeks, hours and minutes, and separate weekday and weekend counts.
• Time zone converter. Moves a specific date and time between any two named zones, with daylight saving applied for that date.
• Direct links to each tool. Add /#/?tab=age to the address and the page opens on the Age tab. The other tabs are ts, diff, tz and clock.
• Nothing uploaded. Every calculation happens on your device.

Benefits of Using Online Date & Time Tools

• No manual counting. Month lengths, leap years and daylight saving are where mental maths slips. A calculator does not.
• One page, five tools. No more switching between separate sites.
• Results you can check. Zone, offset and totals are shown next to the answer.
• Daylight saving handled. Named zones follow the real rules instead of a fixed number of hours.
• Nothing to install. No app, no extension, no free-trial limit. It works on phones and computers.
• Nothing stored. No history and no profile. Close the tab and it is gone.
• Keeps working offline. After the page has loaded, the calculators do not need a connection.

Who Can Use These Date & Time Tools

Developers use the timestamp converter most. A log line reading 1792134772 is not something you read at a glance, and reproducing a bug from a specific local time means turning that time into a number the system accepts. Seeing the offset and the ISO 8601 form on the same screen saves a trip to the terminal.

Everyone else usually has a question about a date. The age calculator helps with forms, visa papers and insurance quotes that need an exact age. The difference calculator answers "how many days until" and "how many days since" for deadlines, invoices, notice periods and holidays, and the weekday count is useful when only working days matter. The time zone converter is for anyone planning a call across countries, where knowing that 3 pm in London is 7:30 pm in India avoids an awkward mix-up. Students, freelancers, project managers and travellers will all find a tab that fits.

How to Read the Current Date and Time

Open the Current Date & Time tab. The clock starts on its own. The big digits are your device's local time, the line under it is the full date, and the small pill names your time zone and its UTC offset. Press Switch to 24-hour to change the format.

The grid below the clock holds the extra details: time zone, offset, current Unix timestamp, ISO week, day of year, days left in the year, quarter and leap year status. Press Copy timestamp to put the current Unix timestamp on your clipboard.

How to Convert a Unix Timestamp

1. Open the Timestamp tab.
2. In the left box, paste the number. Seconds and milliseconds both work. Press Convert, or Use now to try the current time.
3. Read the result: seconds and milliseconds, the date in UTC, in your local time zone, and in ISO 8601.
4. To go the other way, pick a date and time in the right box and press Convert to get the timestamp. The time you enter is read in your own time zone.

How to Calculate Your Exact Age

Open the Age tab and enter a date of birth. The "Age at" box already holds today's date. Change it to find an age on another date, such as for an event next year. Press Calculate age.

The large result shows years, then months and days, the way a form usually wants it. Underneath you get total months, weeks, days and hours, the days left until the next birthday, and the weekday the person was born on. A 29 February birthday is counted on 1 March in years that have no leap day, which is how many official records treat it.

How to Find the Difference Between Two Dates

Open the Difference tab, set the From and To dates and press Calculate. The headline shows total days, with years, months and days under it, and the grid adds weeks, hours, minutes, weekdays and weekend days.

Tick Include the end date if both the first and last day should count. A project from the 1st to the 5th inclusive lasts five days, not four. Swap reverses the dates, and the tool handles a reversed order without error.

How to Convert Time Between Time Zones

Open the Time Zone tab. Enter the date and time, choose the zone it is written in under From, then choose the target zone under To. Press Convert. The list contains every zone your browser knows, so even small cities are covered.

The result shows the converted date and time, and the line below it repeats the source time so you can compare both. Swap zones flips the two and converts again, which helps when you are picking a good time for a call.

A Short Glossary of Date and Time Terms

UTC

Coordinated Universal Time, the world's reference clock. It never shifts for daylight saving.

GMT

Greenwich Mean Time. In daily use it matches UTC, but it is based on the sun rather than atomic clocks.

Unix epoch

00:00:00 UTC on 1 January 1970, the zero point for Unix timestamps.

Unix timestamp

Seconds elapsed since the Unix epoch. Also called epoch time or POSIX time.

Time zone offset

The gap between local time and UTC on a given date, such as +05:30 or −04:00.

Time zone

A named region with its own rules, like Asia/Kolkata. The offset is a result of those rules.

IANA time zone database

The shared record of every zone and every rule change. Your browser holds a copy.

Daylight saving time

Moving clocks forward for part of the year. Countries that use it do not all switch on the same day.

ISO 8601

The standard format that writes the biggest unit first, like 2026-10-16T14:30:00Z.

ISO week

A numbering where weeks start on Monday and week 1 contains the year's first Thursday.

Leap year

A 366-day year with 29 February. It divides by 4, except century years, which must divide by 400.

Leap second

A rare one-second correction to UTC. This page, like most software, ignores it.

Wall clock time

The local time a clock on a wall would show, as opposed to UTC or a timestamp.

Proleptic Gregorian calendar

The Gregorian calendar extended back before its start in 1582. Software uses it for old dates.

Common Date and Time Mistakes

• Assuming all months are equal. Adding a month to 31 January has no clear answer. Counting in days avoids the problem.
• Mixing up offset and zone. Saving +05:30 does not tell you the place or what the offset will be later. Save the zone name.
• Forgetting offsets change. A meeting at "9 am New York time" moves by an hour twice a year for people elsewhere. Named zones handle this, fixed offsets do not.
• Swapping day and month. 03/04/2026 is 3 April in India and the UK, but 4 March in the US. Write 2026-04-03 when entering data.
• Confusing seconds and milliseconds. A wrong guess lands you in 1970 or in the year 50000.
• Trusting old time zone data. Offsets from the distant past are rebuilt from records and are often approximate.
• Counting ranges the wrong way. A stay from the 1st to the 5th may be five nights of cover or four. Agree on the rule before you send the invoice.
• Trusting a wrong device clock. Everything here reads your system time, so a wrong clock makes every result wrong by the same amount.