Use the free tool below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Why the Moon matters to night photography
The Moon is the night photographer’s best friend and worst enemy, sometimes on the same night. A full moon lights landscapes almost like daylight, letting you photograph mountains, deserts, and coastlines at night with short exposures and low noise. The same full moon washes out faint stars, erases the Milky Way, and turns a dark-sky trip into a disappointment. Planning around the Moon is therefore the first step of any night shoot, before location, before weather, and before gear. This calculator tells you what the Moon will do on your date, at your location.
It uses SunCalc to compute the Moon’s illumination as a percentage, its phase name, its age in days, its rise and set times, and the number of days until the next full moon. Enter the date and your latitude and longitude, and you get the full picture in seconds. Illumination near zero means a new moon and the darkest skies. Illumination near one hundred percent means a full moon and the brightest nights. Everything in between is a trade-off, and knowing the number lets you choose deliberately instead of discovering the Moon’s plans when you arrive in the dark.
Reading the Moon’s cycle
The Moon’s cycle lasts about 29.5 days, from one new moon to the next. In the first week after new moon, a thin crescent grows in the evening sky and sets early, leaving the rest of the night dark. That is the sweet spot for star photography: a little moonlight in the early evening for foreground detail, then true darkness later. Around first quarter the Moon is half lit and stays up until midnight. Around full moon it rises near sunset and stays up all night, which is wonderful for moonlit landscapes and terrible for stars. After full moon it rises later each night, so the early evening darkens again and late-night photographers get their darkness back.
Moonrise and moonset matter as much as phase. A half moon that sets at midnight still gives you a dark second half of the night, while a half moon that rises at midnight ruins only the second half. The calculator’s rise and set times let you plan around the Moon’s schedule rather than its phase alone.
A worked example
Suppose you plan a Milky Way shoot and the calculator shows 98 percent illumination with moonrise near sunset. That night is a bad choice for stars, however clear the forecast: the Moon will flood the sky all night. Move the shoot a week later and the calculator shows a waning gibbous near 60 percent rising around midnight. The first half of the night is still moonlit, but after moonset the sky darkens, so plan your star shots for the small hours. Move two weeks from the original date and illumination drops below 10 percent near new moon: the whole night is dark, and that is the night to book.
Now suppose you want moonlit landscapes instead. The full moon night you rejected for stars becomes the perfect choice: the Moon acts as a giant soft light in the sky, shadows are gentle, and exposures stay short. Moonlit landscape photography is often easier than star photography because the light is generous and forgiving. The same calculator serves both goals; only your target changes, and the numbers tell you which nights suit which.
Planning around the Moon
For stars and the Milky Way, aim for the week around new moon, and check moonrise and moonset even then, because a crescent moon low in the sky still adds some glow near the horizon. For moonlit landscapes, aim for the days around full moon, and check that the Moon will actually be above the horizon during your shoot: a full moon below the horizon helps nobody. For moon portraits, when the Moon itself is the subject, any phase works, but the most dramatic Moon photographs come near the horizon at moonrise or moonset, when it looks huge and turns orange.
Combine the Moon forecast with the weather forecast and the dark-sky map. A new moon under cloud is useless, and a full moon in a light-polluted city is doubly bright. The best night shoots happen when all three line up: dark Moon, clear sky, dark site. Those nights are rare enough to be worth planning weeks ahead, which is exactly what this calculator is for.
Frequently asked questions
Does a crescent moon ruin star photos? Not much. A thin crescent adds little light, especially if it sets early. The damage grows with illumination, so anything under about 25 percent is usually fine for stars away from the Moon’s direction.
Why does the Moon look bigger near the horizon? That is a trick of the brain, not optics: the Moon measures the same size wherever it sits. Near the horizon it looks bigger because the brain compares it with trees and buildings, which makes it a superb photographic subject.
Can I photograph the Milky Way at full moon? Barely. The faint Milky Way drowns in moonlight, though bright star clusters and planets still show. Save Milky Way plans for dark nights and use full moons for landscapes.
Moon figures are computed, not observed: clouds, hills, and local glow change what you actually see. Use the calculator above to choose your night, then check the sky on the day.
Related calculators
- Spanish version
- Blue Hour Calculator – Twilight Window for City Lights and Deep Blue Skies
- Film Development Time Temperature Calculator – Corrected Times When Developer Runs Hot or Cold