Convert Fortnight (fortnight) to Day (Sidereal) (d (sidereal)) instantly.
About these units
Fortnight (fortnight)
A fortnight is 14 days, a unit deeply rooted in English tradition. Its name derives from "fourteen nights," reflecting a time when day-to-day life was measured in nights rather than hours or minutes. Fortnights appear in literature, wage schedules, agricultural cycles, and even modern payroll systems in some countries. Though not part of the SI system, the fortnight persists because it occupies a natural middle ground: longer than a week, shorter than a month, yet easily divisible and memorable.
Day (Sidereal) (d (sidereal))
A sidereal day is the time Earth takes to rotate exactly 360 degrees relative to the distant stars—about 23 hours, 56 minutes, 4 seconds. In contrast, the solar day is slightly longer because Earth advances in its orbit each day and must rotate extra degrees for the Sun to appear in the same position in the sky. Sidereal days are fundamental to astronomy: telescopes use sidereal time to track stars, which appear in the same position in the sky at the same sidereal moment each night. This unit anchors astronomical observation to the cosmos rather than to the Sun.