Free Online Date & Time Tools
Convert timestamps, calculate ages and date differences, plan workdays, find countdowns, convert time zones, and track hours between any two moments — 56 free tools, all instant, all private in your browser.
Online Date & Time Tools — Free, Fast & 100% In-Browser
Every tool on this page runs entirely in your browser. No data is ever sent to a server. Convert Unix timestamps to human-readable dates, calculate the exact difference between any two dates in days, weeks, months or years, find the number of business days between dates, figure out the next leap year, calculate precise ages in any unit, convert time zones, plan countdowns, and track work hours — all with no account, no subscription, and no limits.
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Unix Timestamp Converter
Convert Unix epoch timestamps (seconds or milliseconds) to human-readable dates and times, and back. Supports any timezone.
Unix Time to Date
Paste any Unix timestamp and instantly see the full date, time, day name, week number, and ISO 8601 string in any timezone.
Milliseconds to Date
Convert a JavaScript epoch value (milliseconds since 1970-01-01) to a readable date and time, or convert a date back to milliseconds.
Excel Date to Normal Date
Convert Excel or Google Sheets serial date numbers (like 45123) to a human-readable date. Supports both Windows and Mac Excel epochs.
Normal Date to Excel Date
Enter any calendar date and get the Excel/Google Sheets serial number. Useful for spreadsheet formulas, VLOOKUP, and date calculations.
Decimal Hours to Time
Convert decimal hours (e.g. 2.5 → 2:30, 1.75 → 1:45) to hours and minutes format. Essential for timesheets and billing.
Time to Decimal Hours
Convert hours and minutes (e.g. 2:30 → 2.5, 1:45 → 1.75) to a decimal number. Perfect for payroll, billing, and timesheet entry.
Hours to Days Converter
Convert any number of hours to days, hours, and minutes. Works with decimals — e.g. 50 hours = 2 days 2 hours.
Days to Hours Converter
Convert days to total hours. Handles fractional days and lets you include or exclude weekends for work-hour estimates.
Date Difference Calculator
Find the exact number of days, weeks, months, and years between any two dates. Shows total days, business days, and weekends separately.
Business Days Calculator
Count working days between two dates, excluding weekends. Add custom public holidays. Calculate delivery dates, deadlines, and project timelines.
Countdown Timer
Count down to any future date and time — events, birthdays, deadlines, launches. Displays live days, hours, minutes, and seconds remaining.
Days Until Calculator
How many days until a specific date? Enter any future date and get the exact countdown in days — great for planning events and deadlines.
Days Since
How many days have passed since a specific date? Enter any past date and instantly see elapsed days, weeks, months, and the exact duration.
Time Since (Past Date)
Calculate exactly how long ago a date was — down to years, months, days, hours, minutes, and seconds. Great for milestones and anniversaries.
Date Add / Subtract
Add or subtract any number of days, weeks, months, or years to a date. Find out what date it will be 90 days from today, or 6 months ago.
Week Number Calculator
Find the ISO week number of any date, or find what dates fall in a given week number. Supports both ISO 8601 (Monday start) and US (Sunday start) conventions.
Calendar Week Calculator
Calculate the calendar week (CW) number of any date in ISO or regional formats. Widely used in Germany, EU scheduling, and supply chain planning.
Calendar Generator
Generate a visual monthly calendar for any month and year. View all dates, day names, week numbers, and print-ready layout.
Day Number of Year
Find the ordinal day number of any date within the year (e.g. Feb 15 = Day 46). Also shows days remaining in the year. Supports leap years.
Days Left in Year
How many days are left in the current year? See today's day number, days elapsed, days remaining, and the year progress percentage.
Year Progress Percentage
See exactly what percentage of the year has passed. Shows a live progress bar, days elapsed vs remaining, and the precise completion percentage.
Next Leap Year
Find the next (and previous) leap year from any date. See all leap years in a range, and check if any specific year is a leap year with explanation.
Date to Day Name
What day of the week was any date? Enter any date and instantly see the day name (Monday, Tuesday…). Also shows the week number and day of year.
Quarter Calculator
Find which quarter (Q1–Q4) any date falls in for standard calendar or custom fiscal year. Shows quarter start/end dates and days elapsed in the quarter.
Age Calculator
Calculate your exact age in years, months, and days from your date of birth. See your next birthday countdown and total age in days, hours, and minutes.
Age in Months
Calculate someone's exact age in total months. Particularly useful for pediatric healthcare, baby development tracking, and infant milestones.
Age in Weeks
Calculate your exact age in total weeks. Useful for pregnancy tracking, gestational age, newborn development, and precise duration tracking.
Age in Days
Find out exactly how many days old you are. See milestone days (1,000th day, 10,000th day, etc.) and when your next round-number day falls.
Age in Hours
Calculate how many hours old you are. A fun and educational tool that puts your age in a surprisingly large number of hours.
Days Until Birthday
How many days until your next birthday? Enter a birth date and get the exact countdown, the day of the week your birthday falls on, and the upcoming age.
Date Difference in Months
Calculate the precise number of months between two dates. Shows full months, remaining days, and the breakdown — useful for loan terms and project durations.
Date Difference in Years
Find the number of complete years between two dates, with the remaining months and days. Useful for anniversaries, experience calculations, and legal age checks.
Weeks Between Dates
Calculate the number of complete weeks between any two dates. Useful for sprint planning, gestation tracking, and long-range scheduling.
Months Between Dates (Precise)
Calculate the precise number of months (including fractional months) between two dates. Ideal for subscription billing, mortgage amortization, and financial planning.
How Many Fridays Until
Count how many Fridays (or any weekday) remain until a future date. Lists each occurrence date — great for event planning and payroll cycles.
Weekday Counter
Count how many times a specific day of the week (e.g. Mondays) occurs between two dates. Lists all dates and the total count.
Hours Between Two Times
Calculate the exact hours and minutes between any two times on the same or different days. Handles overnight shifts and shows decimal hours too.
Minutes Between Dates
Calculate the total number of minutes between any two date-times. Useful for SLA tracking, meeting durations, and precise interval measurements.
Workweek Calculator
Calculate working days in a custom workweek. Set your schedule (Mon-Fri, Mon-Sat, custom) and count working days in any date range.
Work Hours Remaining Today
Enter your shift end time and see exactly how many hours, minutes, and seconds remain in your workday — with a live countdown bar.
Payroll Hours Calculator
Calculate total worked hours across multiple shifts, subtracting break and lunch times. Shows regular vs overtime hours and estimated pay.
Overtime Calculator
Calculate overtime pay for hours worked beyond your standard weekly hours. Set your regular rate, overtime multiplier (1.5×, 2×), and get a full pay breakdown.
Time Until Break
Set your next break or lunch time and get a live countdown. Supports recurring break intervals (e.g. every 90 minutes) to help structure your workday.
Time Until
Live countdown to any time of day — meetings, deadlines, end of shift. Shows hours, minutes, and seconds remaining with a progress bar.
Seconds Countdown
Set any number of seconds and start a countdown timer. Plays an alert when done. Useful for presentations, cooking, and timed exercises.
Fiscal Year Calculator
Determine the fiscal year, quarter, and period for any date. Supports US (Oct–Sep), UK (Apr–Mar), Australia (Jul–Jun), and custom fiscal year start months.
Timezone Converter
Convert any date and time between any two time zones. Supports all IANA time zones — great for scheduling international meetings and calls.
Time Zone World Clock
View the current time in multiple cities and time zones simultaneously. Add up to 10 locations, compare UTC offsets, and see DST status for each.
Time Zone Offset Calculator
Calculate the UTC offset and the hour difference between any two time zones. Accounts for daylight saving time changes and shows current and next DST transitions.
Alarm Duration Calculator
Set a future alarm time and see exactly how long until it goes off in hours, minutes, and seconds. Useful for planning sleep and timed activities.
Time Since Event (Any TZ)
Calculate how long ago a global event happened in any time zone. Enter date, time, and timezone and get elapsed time from that exact moment worldwide.
Bedtime Calculator
Enter your wake-up time and get the ideal bedtimes based on 90-minute sleep cycles. Wake up between cycles to feel refreshed — not groggy.
Nap Length Calculator
Find the optimal nap duration — 10, 20, or 90 minutes — based on your available time. Shows wake-up time and the type of sleep benefit you'll get.
Sleep Countdown
Set your bedtime and get a live countdown showing exactly how long until you should sleep. Includes a sleep quality reminder and screen-time wind-down alert.
Hours Awake Calculator
Calculate how many hours you've been awake since your wake-up time, and how many hours of sleep you'll get if you sleep now until your alarm.
Why use LazyTools for date & time calculations?
100% Private & In-Browser
Every calculation happens locally in your browser using JavaScript. No dates, times, or personal data are ever sent to a server. Nothing is stored unless you save it yourself.
Instant — No Waiting
All 51 tools give real-time results as you type. No form submission, no page reload, no loading spinners. Date calculations, time zone conversions, and countdowns update live.
Built for Real Workflows
From Unix timestamps used by developers, to payroll hours for HR, to sleep cycle bedtimes for everyday use — each tool was designed around actual use cases, not generic demo features.