Free Online Clock & Time Tools

Yes, completely. Once OnlineTimeZone has loaded in your browser, the alarm system runs 100% offline. All alarm sounds are synthesized locally using the Web Audio API — there are no external audio files to fetch, so even if your WiFi disconnects, your alarms will still ring on schedule.

Yes, the alarm will still trigger as long as the tab remains open in your browser. Modern browsers continue running JavaScript timers in background tabs. However, some aggressive battery-saving modes on mobile devices may throttle background tabs, so we recommend keeping the tab visible for critical wake-up alarms.

Absolutely. You can add as many alarms as you need — simply select a new time and click "Add Alarm" repeatedly. All active alarms appear in the list sorted chronologically. The browser tab title also updates to show your next upcoming alarm time so you always know what is scheduled at a glance.

When your alarm rings, you can snooze it for 1, 5, 10, 15, 30, or 60 minutes — configurable in Settings. The snooze duration shifts the alarm forward by your chosen interval and re-enables it automatically. You can change your default snooze duration at any time in the Settings panel.

OnlineTimeZone offers three synthesized alarm sounds: a soft Chime, a sharp Digital Beep, and an urgent Siren Alert. All sounds are generated in real-time by the Web Audio API — no sound files are downloaded. You can also adjust the alarm volume from 0 to 100 using the volume slider in Settings, and toggle looping so the alarm repeats until dismissed.

You can set up to 99 hours, 59 minutes, and 59 seconds — giving you a maximum countdown of nearly 100 hours. This makes it suitable for everything from quick 30-second intervals to multi-day event countdowns. Simply enter your desired hours, minutes, and seconds in the input fields and press Start.

Yes. The Start button becomes a Pause button once the timer is running. Click Pause to freeze the countdown at its current value, then click Resume to continue from exactly where it left off. The circular progress ring also pauses and resumes along with the timer, giving you a clear visual indicator of remaining time.

Yes. Click the expand icon in the top right corner of the Timer section to enter full-screen mode. The timer display scales up to fill your entire monitor — ideal for teachers managing classroom activities, gym instructors running interval sessions, or anyone presenting to an audience who needs to see the timer clearly from a distance.

Yes. When the countdown reaches zero, a modal popup appears and the alarm sound plays automatically. The sound type and volume are controlled by your Settings — choose from Chime, Digital Beep, or Siren. Click Dismiss to stop the sound. The timer resets automatically after finishing so you can start a new countdown immediately.

Absolutely. The Pomodoro technique involves 25-minute focused work intervals followed by 5-minute breaks. Set the timer to 25:00, work until it rings, then reset and set 05:00 for your break. The visual progress ring makes it easy to gauge how much of your Pomodoro session remains without having to check the exact time.

Extremely accurate. The stopwatch uses requestAnimationFrame and compares elapsed time against the system's high-resolution timestamp (Date.now()) on every frame. This means it does not rely on setInterval counting, which can drift. The result is a stopwatch with no cumulative drift error regardless of how long it runs — making it suitable for athletic timing, lab experiments, and developer benchmarking.

Click the Lap button while the stopwatch is running to record the current elapsed time as a lap. Each lap is saved and displayed in the Laps panel on the right, numbered from most recent at the top. The stopwatch continues running while you record laps — it does not reset between laps. This gives you a continuous total time alongside individual lap splits, just like a professional sports stopwatch.

There is no hard limit — you can record as many laps as needed. All laps are stored in your browser session memory and displayed in a scrollable list. Note that laps are cleared when you click Reset or refresh the page, as OnlineTimeZone does not store any data on external servers. Your data stays entirely on your device.

Yes, developers frequently use the stopwatch to measure rough execution times for processes, builds, or workflows that take several seconds or minutes. For precise microsecond-level benchmarking inside code, use the browser's built-in Performance API (performance.now()), but for timing real-world workflows and processes, this stopwatch is ideal.

Yes. The stopwatch keeps running in the background even if you switch to another tab, because it records your start timestamp and recalculates elapsed time each frame rather than relying on a counter that could be throttled. When you return to the tab, the display immediately shows the accurate elapsed time with no missed time.

There is no practical limit. You can set a countdown to an event years or even decades in the future. The countdown will accurately display the remaining days, hours, minutes, and seconds for any future date your browser's date picker supports. Popular uses include countdowns to New Year, Christmas, weddings, retirement dates, and major sporting events.

Yes. The "Event Name" field at the top is optional but lets you label your countdown with a personalised title like "My Wedding Day", "New Year 2027", or "Product Launch". This label appears prominently above the countdown numbers as it runs, making it easy to identify what you are counting down to at a glance.

When the event time arrives, all countdown values reset to zero and the display changes to a celebratory "Event Reached!" message. There is no alarm sound for the event countdown by design — keeping it clean and distraction-free for public-facing countdowns on screens. For an alarm at a specific time, use the Alarm Clock section instead.

Yes. Click the expand icon to enter full-screen mode and the countdown scales up to fill any screen. The large day, hour, minute, and second numbers are highly readable from a distance, making this ideal for event venues, conference rooms, retail countdowns, and classroom display boards showing an upcoming deadline or exam date.

The countdown uses your device's local system time and the local date and time you enter as the target. If you need to count down to an event happening in a different time zone, first convert the event's time to your local time using our Time Zone Converter tool, then enter that converted local time into the Event Countdown.

You can add any of the 400+ time zones in the full IANA timezone database, which covers every country and territory on Earth. Simply type a city name or region into the search field — for example "Tokyo", "America/Chicago", or "Europe/Paris" — and select your match from the dropdown. Add as many cities as you need to your personal world clock grid.

Yes. Every clock in your world clock grid updates every second, showing the live current time for each city. The date is also displayed below each clock, which is important for cities that are a day ahead or behind your local time — especially relevant when coordinating across regions like Australia and the United States or Asia and Europe.

The world clock starts with five major global cities: New York (Americas), London (Europe/UTC), Tokyo (East Asia), Sydney (Oceania), and Dubai (Middle East/Gulf). These five cover the main trading and business time zones across the world. You can remove any of these and replace them with the cities most relevant to your work or personal life.

Yes. All time calculations use your browser's built-in Intl (Internationalization) API with the official IANA timezone database, which includes all historical and current Daylight Saving Time rules for every region. When clocks spring forward or fall back in any country, the world clock automatically reflects the correct local time without any manual adjustment needed.

Yes. Add your team members' cities to the world clock grid, then check all the times simultaneously to identify an overlapping window that works for everyone. For example, if you need a time that works for London, Mumbai, and New York, you can see all three live times side by side and quickly spot a suitable slot. For detailed conversions, also try our dedicated Time Zone Converter tool.

Select today's date in the Start Date field, choose "Add", enter 90 in the Days field (leave Years and Months at 0), then click Calculate Date. The result instantly shows you the exact calendar date 90 days from your start date. This is commonly used to calculate delivery deadlines, contract expiry dates, payment due dates, and probation end dates.

Yes, automatically. When you add months or years to a date, the calculator correctly handles February 29th in leap years. For example, adding one year to February 29, 2024 will give you February 28, 2025 — because 2025 is not a leap year and February only has 28 days. All edge cases involving varying month lengths are handled correctly without any manual adjustment.

Yes. Select your start date, choose "Subtract", and enter the years, months, and days you want to subtract — or alternatively, think of it as finding what date falls a certain interval before your chosen date. For a direct days-between-dates calculation, subtract the earlier date from the later one using the Years/Months/Days fields to find the exact interval in calendar units.

Extensively. Common business uses include calculating contract notice periods (e.g. 30 or 90 days), project milestone deadlines, invoice payment due dates (Net 30, Net 60), subscription renewal dates, employee probation end dates, warranty expiry dates, and regulatory compliance filing deadlines. Legal professionals use it for statute of limitations calculations and court-ordered date arithmetic.

Yes. You can enter any combination of years, months, and days simultaneously and the calculator applies them all in a single operation. For example, subtracting 2 years, 3 months, and 15 days from a date gives you the precise result accounting for all calendar rules. This is useful for calculating historical dates, backdating documents, or finding dates relative to past events.

The calculator subtracts your date of birth from the target date (today by default) using proper calendar arithmetic. It first calculates full completed years, then remaining full completed months, then the leftover days. This accounts for the fact that months have different lengths (28 to 31 days) and that leap years add an extra February 29th, giving you a precisely accurate breakdown rather than an approximate one.

Yes. The "Age at Date" field lets you enter any date — past or future — to calculate how old you were or will be on that specific day. This is useful for calculating your age at historical milestones, finding out how old you will be on a future birthday or anniversary, determining age eligibility for events or services, or calculating age for legal and medical purposes.

If you were born on February 29th, the calculator treats February 28th as your birthday in non-leap years for the purpose of counting completed years. This matches the standard legal and civil convention used in most countries for leap-day birthdays. The remaining months and days in the breakdown adjust accordingly to give an accurate result every year.

Medical professionals — especially paediatricians and neonatologists — frequently need a patient's exact chronological age in months and days to assess developmental milestones, calculate medication dosages based on weight and age, and evaluate growth percentiles against standardised charts. The precise years-months-days breakdown this tool provides is more useful for clinical purposes than a simple "X years old" figure.

Yes. HR professionals and individuals commonly use this calculator to determine whether someone has reached a specific age threshold — for example, the minimum retirement age of 60 or 65 in different countries, or eligibility ages for pension schemes, senior discounts, and government benefits. Enter the person's date of birth and today's date to instantly see their exact current age in years, months, and days.

Enter your shift start time (for example, 09:00) and your end time (for example, 17:30) and click Calculate. The result will show 8 hours and 30 minutes. The calculator supports 24-hour time format. For overnight shifts where your shift starts in the evening and ends the following morning, the calculator automatically handles the midnight crossover so you always get the correct total hours.

Yes, this is one of the most important features. If your end time is before your start time — for example, a night shift from 22:00 to 06:00 — the calculator detects this and adds 24 hours to the calculation, giving you the correct result of 8 hours. Many simpler time calculators produce incorrect negative results for overnight shifts; OnlineTimeZone handles this automatically.

Freelancers enter their start and end time for each work session to get the total hours worked. Multiply the result by your hourly rate to calculate your invoice amount. For example, if you worked from 10:30 to 16:45, the calculator shows 6 hours and 15 minutes (6.25 hours). At a rate of ₹2,000 per hour, your invoice would be ₹12,500. It is the fastest way to verify timesheet entries before billing clients.

The calculator displays results in hours and minutes format (e.g., 8h 30m). To convert to decimal hours for billing or payroll purposes, divide the minutes by 60 and add to the hours. So 8h 30m becomes 8 + (30/60) = 8.5 decimal hours. Alternatively, a quick mental shortcut: 15 minutes = 0.25, 30 minutes = 0.50, 45 minutes = 0.75 of an hour.

Yes. A common approach is to calculate your total shift duration, then separately calculate your break duration (e.g., a 45-minute lunch break), and subtract manually. For example, if you work 09:00–17:45 (8h 45m total) and take a 45-minute lunch, your actual paid hours are 8h 00m. Many users run two quick calculations — total shift and break duration — to get their net billable or payroll hours quickly.

Enter the time you want to convert in the "Time in Source Zone" field, select your source time zone from the first dropdown (it auto-detects your local zone by default), then choose your target time zone from the second dropdown and click Convert. The result shows the equivalent time in your target zone, fully accounting for the UTC offset difference and any applicable Daylight Saving Time rules.

Yes, completely automatically. The converter uses the Intl.DateTimeFormat API with the full IANA timezone database, which contains all historical and current Daylight Saving Time rules for every country and region. Whether you are converting a time in summer (when many regions observe DST) or winter (when most regions revert to standard time), the correct offset is applied without any manual input from you.

All 400+ time zones in the IANA (Internet Assigned Numbers Authority) timezone database are available. This includes every country, territory, and historical time zone on Earth — from America/New_York and Europe/London to Asia/Kolkata, Pacific/Auckland, and even unusual zones like Asia/Kathmandu (UTC+5:45) and Asia/Kolkata (UTC+5:30). Simply search or scroll through the dropdown to find your zone.

Use the converter to check what your proposed meeting time looks like in each participant's time zone. For example, if you want to schedule at 10:00 AM New York time, convert it to London (typically 3:00 PM GMT) and Mumbai (typically 8:30 PM IST) to check if those times are reasonable working hours. For a visual overview of multiple cities simultaneously, use the World Clock tool to see all times side by side.

UTC (Coordinated Universal Time) is the global time standard with no offset — it is the baseline from which all other time zones are measured. GMT (Greenwich Mean Time) is historically the same as UTC and used interchangeably in everyday language. Standard time zones like EST (Eastern Standard Time) or IST (Indian Standard Time) are defined by their fixed offset from UTC — for example, IST is UTC+5:30. The IANA database used by this converter uses named zones (like Asia/Kolkata) rather than abbreviations, because abbreviations like "CST" can refer to multiple different zones worldwide.