Day Counter — Count the Days and Weeks Between Two Dates

Calculate the exact number of days, weeks, months, and years between any two dates — instantly and for free. Use it to find how many days since a date, how many days until your birthday or Christmas, or what date falls 30, 60, 90, or 180 days from today.

It also counts business days: Saturdays and Sundays are removed automatically, and you can enter how many public holidays fall inside the range, since those differ by country. That is the figure contracts, notice periods and delivery windows are usually written in.

Created by Ashar PervaizLast updated 31 October 2026

Three Different Questions, One Calculator

People arrive at a date calculator wanting one of three things, and although they all involve counting days, they are not the same calculation.

The third is the one people most often work out by hand and get wrong, because it requires stepping across month boundaries of unequal length. Counting forward 90 days from a date in August lands in November, and getting there mentally means knowing whether each intervening month has 30 or 31 days.

What Date Falls 30, 60, 90 or 180 Days From Today?

These are the counts that appear most often in notice periods, refund windows and probation terms. The table recalculates against the current date every time the page loads, so the answers below are for today rather than for whenever this was written.

For any other interval, enter today as the start date above and the target date as the end date.

How Many Weeks Between Two Dates

Pregnancy, notice periods, course lengths and project sprints are all counted in weeks rather than days, and the weeks between two dates is the one piece of date arithmetic that is genuinely simple: divide the days by seven. The remainder is what people get wrong, because they round it away.

Sixty days is eight weeks and four days, not "about two months". Ninety days is twelve weeks and six days. The calculator above gives both the whole weeks and the days left over, because a notice period that ends mid-week ends on a specific day and that day is usually the thing being argued about.

A full year is 52 weeks and one day — two days in a leap year — which is why a date does not fall on the same weekday next year, and why anything scheduled "every 52 weeks" drifts backwards through the calendar one day at a time.

The Off-by-One Problem

Ask how many days there are between 1 March and 8 March and you can justify two answers. The difference is seven days. The number of dates in the range, counting both ends, is eight. Neither is wrong; they answer different questions.

Difference between the dates = 7
Days in the range including both ends = 8
Days in the range including one end = 7

This matters far more than it sounds, because the convention differs by context and money often depends on it.

When a deadline matters, the safest habit is to state the end date explicitly rather than the number of days. "Due by 30 September" cannot be misread; "due in 30 days" depends on whether today counts.

Calendar Days Are Not Working Days

A great many delivery promises, refund windows and legal deadlines are quoted in working days, which do not map onto calendar days at any fixed ratio.

Five working days from a Monday is the following Monday — seven calendar days. Five working days from a Thursday is the Thursday after next — eleven calendar days, because two weekends fall inside it. The same promise means different things depending on the day it was made, which is why a refund quoted as five working days can arrive anywhere from a week to a fortnight later.

Public holidays extend it further and are not consistent between countries or even between regions of one country. Any working-day calculation that crosses a holiday period needs the specific calendar for the specific place, which no general tool can supply.

Days Are Exact. Months and Years Are Not.

A day is a fixed unit, so a count of days between two dates is an exact answer. Convert that to months or years and it stops being exact, because those units vary in length.

• Months run from 28 to 31 days. There is no fixed number of days in a month, so "three months" and "90 days" are different periods that happen to be close.
• Years run to 365 or 366 days, so any conversion using 365 drifts by a day every four years.
• Weeks are the only larger unit that is exact, at precisely seven days, which is why week counts never disagree.

The practical consequence appears in contracts. A payment term of 30 days from 31 January falls on 2 March in a normal year. A term of one month from the same date falls on 28 February. Those are different dates from what looks like the same instruction, and which applies depends on the wording.

Month-end arithmetic has a second trap. Adding one month to 31 January has no exact answer, because 31 February does not exist. Different systems resolve it differently — some clamp to the last day of the target month, others roll into March. If a schedule depends on month-end dates, spell out which rule applies rather than assuming.

Leap Years, and the Rule Most People Half-Know

The familiar version is that every fourth year has an extra day. The full rule has two exceptions, and it exists because a solar year is slightly less than 365.25 days.

Divisible by 4 → leap year
unless divisible by 100 → not a leap year
unless also divisible by 400 → leap year after all

So 1900 was not a leap year and 2000 was, which is the case that catches people and caught a great deal of software. The next century year to break the pattern is 2100, which will not be a leap year despite being divisible by four.

For everyday spans this matters in one specific way: any period crossing 29 February contains one more day than the same span in an ordinary year. Counting days between two dates handles this automatically. Estimating by multiplying years by 365 does not.

Where Date Arithmetic Quietly Goes Wrong

• Ambiguous formats. 03/04/2026 is 3 April in most of the world and 4 March in the United States. When a date crosses borders, write the month as a word or use the year-month-day order.
• Time zones. A deadline at midnight is a different moment in different places, and a date recorded in one zone can shift by a day when read in another. Deadlines that matter should name a time zone.
• Daylight saving. Two days a year are not 24 hours long. This does not affect whole-day counts, and it does affect anything measured in hours across the changeover.
• Two-digit years. Still common in handwritten and legacy records, and still ambiguous about the century.
• Estimating rather than counting. Multiplying years by 365 to get a day count ignores leap days, so the error grows by one day roughly every four years.

For an exact age in years, months and days rather than a raw day count, use the age calculator. For durations measured in hours and minutes instead of dates, the time calculator handles that arithmetic, and our guide to calculating exact age works through the borrowing rules step by step.

Counting in weeks rather than days is the common case for notice periods and pregnancies, and the calculator above gives both. For the things a date arithmetic question usually leads to, the age calculator handles birthdays properly, including the leap-year edge case.

Date Counting Questions