Date Calculators For Family Historians

The calculators and converters on this page perform several date-related functions that may be of use to family historians. They work with dates on both the Julian calendar and the Gregorian calendar, from 1200 to the present. Where applicable, the results are in either Old Style or New Style (O.S. or N.S). There may be a slight delay in displaying the results after clicking the button, however, they will appear next to the button.

More date calculators and converters are available on the Time and Date website.

Day of the Week

This calculator determines the day of the week of the date entered. It uses Zeller’s congruence for the Julian calendar and the Gregorian calendar.

The date, month and year can be typed into the form or the date can be selected by clicking the calendar icon.

Date:

Easter Day Calculator

This calculator determines the date Easter fell on in the year submitted.

Year:

CALCULATE

Old Style to New Style Converter

This converter changes a date from Old Style (O.S.) to New Style (N.S.).

The date, month and year can be typed into the form or the date can be selected by clicking the calendar icon.

Old Style Date:

Convert

Regnal Years

This tool calculates the regnal year that a calendar date falls in and the calendar dates of regnal years.