9 free date and time calculators for everyday use — age, working hours, time zones, and date differences.
| You want to | Use |
|---|---|
| Work out an exact age in years, months and days | Age Calculator |
| Add or subtract days, weeks or months from a date | Date Calculator |
| Count the days between two dates | Day Counter |
| Find what date falls a set number of days ahead | Days From Today |
| Find the weekday for any date | Day of the Week |
| Add up hours and minutes | Hours Calculator |
| Work out a duration between two times | Time Duration |
| Total a week of shifts including breaks | Time Card Calculator |
| Do arithmetic on times | Time Calculator |
| Convert between time zones | Time Zone Calculator |
Dates look simple and are not. Months have different lengths, years occasionally have an extra day, and clocks jump twice a year in half the country.
"One month later" has no single answer. What is one month after 31 January? There is no 31 February. Different systems answer 28 February, 2 March, or 3 March, and all three are defensible. Our date calculator clamps to the last valid day of the target month, which is the convention most people expect and the one used in most contracts — but if a deadline matters legally, check how the agreement defines it rather than trusting any calculator.
| Trap | What happens |
|---|---|
| Leap years | Every 4 years, except century years, except those divisible by 400. 1900 was not a leap year; 2000 was |
| Month-end rollover | 31 January plus one month has no exact answer |
| Inclusive vs exclusive counting | Monday to Friday is 4 days apart but 5 days of work |
| Daylight saving | One day a year has 23 hours, another has 25 |
| Public holidays | Differ by state, and some shift when they fall on a weekend |
Inclusive counting is worth pausing on. If a task runs Monday to Friday, the difference between the dates is 4 days, but you have worked 5. Neither is wrong — they answer different questions. Leave loading, notice periods and rental agreements often specify which they mean, and the gap of one day is a common source of disputes.
Australia uses three standard time zones, which becomes five in summer because only some states observe daylight saving.
| Zone | Standard | Daylight saving | States |
|---|---|---|---|
| AEST / AEDT | UTC+10 | UTC+11 | NSW, VIC, TAS, ACT observe DST. QLD does not |
| ACST / ACDT | UTC+9:30 | UTC+10:30 | SA observes DST. NT does not |
| AWST | UTC+8 | none | WA |
In summer, Australia runs on five different times at once. Sydney and Brisbane are in the same zone for half the year and an hour apart for the other half. Perth can be three hours behind Melbourne in summer and two in winter. Adelaide's half-hour offset catches people out year-round. If you schedule meetings across states, this is the single most useful thing to know — and why a national call at 9am Perth time is midday in Sydney in winter and 1pm in summer.
Daylight saving in the observing states runs from the first Sunday in October to the first Sunday in April. Clocks go forward at 2am and back at 3am, so the changeover days are 23 and 25 hours long respectively.
Adding hours is the most common workplace use of these tools, and decimal conversion is where it usually goes wrong.
7 hours 45 minutes = 7.75 hours (45 ÷ 60 = 0.75)
not 7.45 hours
Payroll systems work in decimal hours, so 7:45 on a timesheet becomes 7.75 for pay. Reading it as 7.45 undercounts by 18 minutes a shift — around an hour and a half over a fortnight. The time card calculator handles the conversion and lets you deduct unpaid breaks.
Keep your own record. Under the Fair Work Act, employers must keep time and wage records for seven years, but discrepancies are far easier to raise when you have your own notes of what you actually worked. A timesheet total is a starting point for a conversation, not proof by itself.
How do I calculate my exact age?
Count the completed years from your birth date, then the completed months, then remaining days. The age calculator handles leap years and month lengths, which a rough subtraction of years will not.
How many working days are between two dates?
Count the total days, remove weekends, then remove public holidays. Holidays vary by state and some move when they land on a weekend, so a national figure will be wrong for at least one state.
Why is 7:45 not 7.45 hours?
Because minutes are sixtieths, not hundredths. Forty-five minutes is 45 ÷ 60 = 0.75 of an hour, so 7:45 is 7.75 decimal hours. This is the most common timesheet error and it always undercounts.
Which Australian states have daylight saving?
New South Wales, Victoria, Tasmania, South Australia and the ACT. Queensland, the Northern Territory and Western Australia do not, which is why the country runs on five different times each summer.
Fair Work Ombudsman — Hours of work and record keeping · australia.gov.au — Public holidays by state · National Measurement Institute — Australian time standards