Free · Plan around useful outdoor light

Civil Twilight Planner

Find the morning and evening civil-twilight windows around sunrise and sunset.

  • SunCalc 2 astronomy
  • Private in your browser
  • JSON and CSV downloads

Plan civil twilight

Use the sample place or enter coordinates. All times use the chosen time zone.

1
Choose place and timeCoordinates stay on this device
2
Read the sky planToronto · America/Toronto
Your local result will appear hereUse the sample place, then press the gold button.

Three simple steps

How to use it

  1. Choose a place and date.
  2. Read both civil-light windows.
  3. Allow for clouds and blocked horizons.

Your place stays on this device

SunCalc does the sky math inside this browser tab. Bookify does not upload or save coordinates, dates, or times. Results assume a clear, level horizon; terrain, weather, and buildings can change what you see.