How is the quarter calculated?

For calendar quarters the year is split into four three-month blocks: Q1 is Jan–Mar, Q2 Apr–Jun, Q3 Jul–Sep, Q4 Oct–Dec. The quarter is found from the month index using floor(monthIndex / 3) + 1.

What is a fiscal quarter?

A fiscal quarter follows a fiscal year that may not start in January. If your fiscal year starts in April, then April–June becomes fiscal Q1, July–September Q2, and so on. The tool shifts the month before grouping so the quarters align to your chosen start month.

Which quarter does a date on a quarter boundary belong to?

Quarters are inclusive of their first and last day. For calendar quarters, 31 March is the last day of Q1 and 1 April is the first day of Q2, with no gap or overlap between them.

Why might my fiscal quarter cross a calendar year?

When the fiscal year starts after January, later fiscal quarters fall in the next calendar year. For example, with an April start, fiscal Q4 covers January to March of the following calendar year.

Is any data uploaded?

No. The calculation is pure date arithmetic that runs entirely in your browser. The date you enter never leaves your device.

Quarter of Year Calculator

The quarter of year calculator tells you which three-month quarter a date belongs to — either the standard calendar quarter or a fiscal quarter aligned to a custom year-start month. It is useful for reporting, accounting, planning, and tagging records by period.

How it works

A year has twelve months grouped into four quarters of three months each. For calendar quarters, the quarter is computed directly from the month: with months numbered 0–11, the quarter is floor(month / 3) + 1. That gives Q1 = Jan–Mar, Q2 = Apr–Jun, Q3 = Jul–Sep, Q4 = Oct–Dec.

For a fiscal year that starts in a month other than January, the tool first shifts the month so the fiscal start becomes month 0:

shifted = (month - fiscalStartMonth + 12) % 12
fiscalQuarter = floor(shifted / 3) + 1

It then computes the first and last calendar dates of that quarter, which may roll into the next calendar year when the fiscal year does not start in January.

Example

With a fiscal year starting in April:

April, May, June → fiscal Q1
July, August, September → fiscal Q2
A date in February falls in fiscal Q4, and that quarter’s range runs January–March of the following calendar year.

All arithmetic is local to your browser — nothing is sent anywhere.