Calendar desk
Quarter of the Year
Find the calendar quarter containing a date.
Quarter of the Year: Place a date in its calendar quarter, from Q1 for January to March through Q4 for October to December. The result includes both the number and a Q label. It uses a January-start year and cannot infer an organisation's fiscal quarter from its reporting schedule. Runs 100% locally in your browser with zero server file uploads.
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Quarter number
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- Quarter
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Quarter = floor(month ÷ 3) + 1- Dates are calendar dates at UTC midnight; no local timezone or daylight-saving adjustment is applied.
- Results are planning utilities. Public holidays, locale-specific work rules, and company policies are not inferred.
- Quarters use calendar-year boundaries: Q1 January–March, Q2 April–June, Q3 July–September, Q4 October–December.
Quarter formula and month groups
Let M be the input's month number, with January = 1 and December = 12. Quarter Q = floor((M − 1) ÷ 3) + 1. The four groups are Q1: January, February, March; Q2: April, May, June; Q3: July, August, September; Q4: October, November, December. The day and year do not enter this formula.
For 2025-07-15, M = 7. Subtract one to obtain 6, divide by 3 to obtain 2, then add one: Q = 3. The widget returns quarter number 3 and label Q3. July's first and final dates would be classified in the same group because both have month number 7.
Calendar versus fiscal reporting
The IRS explanation of tax years (https://www.irs.gov/businesses/small-businesses-self-employed/tax-years) distinguishes a January-to-December calendar year from fiscal accounting periods. That is a useful reminder to check which year your report means; the calculator itself applies only calendar quarters.
For an April-start reporting year divided into three-month periods, April to June would be fiscal Q1 even though this page calls those dates calendar Q2. Label exported figures explicitly as calendar quarters to prevent that mismatch. A quarter number also repeats annually, so include the year when filing invoices or comparing seasonal activity. Special week-based accounting calendars need their own period boundaries.
How to use it
- Choose the date to classify.
- Calculate its calendar quarter.
- Use the number and Q label with the date's calendar year when organising records.
Privacy & limitations
Dates, times and results stay in your browser. No inputs are uploaded.
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Frequently asked questions
Can I change the year to start in April?
This tool has no fiscal-start setting. It always groups January through March as Q1. If your fiscal year begins in April, you must map the returned calendar quarter to your own reporting periods.
Does the last day of March belong to the second quarter?
No. Every March date remains in Q1. Q2 begins on 1 April, so neither the day number nor the time of day changes the classification of a March calendar date.
Are all four quarters the same length in days?
No. Each contains three months, but those months have different lengths. A leap day also changes the length of Q1. The result classifies the month; it does not calculate a quarter's duration.
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