Free Tool

Real Estate Twilight Calculator

What the times mean

Every time on the plan is a height of the sun, worked out for that spot and date:

• Sunset is when the top of the sun drops below a flat horizon (0.833° below, which allows for the atmosphere bending the light), the same definition the US Naval Observatory uses.
• The blue hour is when the sun is 4° to 6° below the horizon, the common photographers' definition. The sky is at its deepest even blue and the lit windows balance against it.
• Civil dusk is when the sun reaches 6° below. After that the sky goes dark quickly, and an exterior starts to look like a night shot instead of a twilight one.

The plan then works back from sunset: arrive an hour before to scout the angle and set up, have every light on 15 minutes before sunset, and start the twilight frames about 10 minutes after it. Those offsets are the ones in our twilight photography guide. The times were within 2 minutes of the US Naval Observatory's for Denver, Miami, Seattle and Anchorage, the places we checked.

How long is the twilight window?

It depends on where you are and the time of year, which is why a fixed "15 minutes after sunset" rule lands differently in Miami and Seattle. Closer to the equator the sun drops more steeply and twilight is short; further north it slides down at an angle and lasts longer, most of all in summer. It's shortest around the spring and fall equinoxes. Minutes from sunset to civil dusk, from the calculator:

The blue hour itself is shorter than its name: 9 to 16 minutes in those four lower-48 cities. In Miami in September you have about 13 minutes of twilight frames after the first 10; in Seattle in June, about 31. On the shortest evenings, have the angle composed and the brackets set before sunset, so the window goes on shooting, not setup. In Anchorage in June the sun never gets 6° below the horizon, so twilight lasts until dawn; the calculator says so when that happens.

Which way the house faces changes the twilight sky

You shoot the front of the house, so you're facing the opposite way from the front. If the front faces east, you're looking west, toward where the sun went down: the brightest, warmest part of the sky is behind the roof. That's the most colorful frame, but early in the window the sky can be far brighter than the house, so it often works best a few minutes later than you'd think. If the front faces west, you're looking east, into the darker side of the sky, which turns deep blue sooner and makes the lit windows stand out. Neither is wrong. The calculator tells you which one you have, and where the sun sets, so you know before you arrive.

When is the sun on the front?

The same position math shows the daytime light. Pick the direction the front faces and the calculator lists when the sun is up and on the front of the house, and when it is also at least 15° up and within 60° of straight on. That second window is our rule of thumb for good front light: high enough to clear most trees and light the facade, and square enough not to rake across it. It matches the advice in our guide to the best time of day for real estate photography: book an east-facing front in the morning and a west-facing one in the afternoon. A front that faces north in the northern US gets no direct sun at all for much of the year, which means even, soft light at any hour.

Finding the coordinates

The calculator needs the house's latitude and longitude, not the address. The math runs in your browser, so the location isn't sent anywhere. In Google Maps on a computer, right-click the house: the first line of the menu is the coordinates, and clicking it copies them. On a phone, press and hold the house to drop a pin; the coordinates show in the search box. You can also paste the link from the address bar while Google Maps shows the house (shortened share links don't include the location). On site, Use my location reads your phone's position. Within a few miles is close enough: in the middle of the US the times shift by about a minute for every 13 miles east or west.