Sandburg Center for Sky Awareness
A Fairfax County Public Schools Planetarium

Daylight Calculator

Use the SCSA Daylight Calculator to calculate the number of hours of daylight--also known as the Duration of Insolation (Incoming Solar Radiation)--by subtracting the time of sunrise from the time of sunset. Input times should be expressed in 24-hour format: A.M. times are in 24-hour format already; convert P.M. times by adding 12 hours. For example, 5:16 p.m. is equivalent to 17:16 hours.

Obtain the times of sunrise and sunset for your location by visiting one of the following U.S. Naval Observatory Web pages:

Sunrise time (hh:mm, 24-hour format):
Sunset time (hh:mm, 24-hour format):

© Copyright 2002-2012 Walter Sanford & Phillip Wherry. All rights reserved.

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