Moonrise & Moonset Calculator

This calculator finds moonrise, moonset and the moon's upper transit — the moment it stands highest in the sky — for any latitude, longitude and date, along with its phase, illuminated fraction, age and distance. Everything runs in your browser: no location data is sent anywhere, and the tool keeps working offline.

Why the moon is harder than the sun. The sun's position barely changes over a single day, so sunrise can be solved in closed form from one declination value. The moon moves about 13° a day against the stars — roughly its own diameter every hour — so no single position describes the whole day. This tool instead samples the moon's altitude across the date at five-minute intervals and narrows in on each horizon crossing by bisection, recomputing the moon's position at every step.

The horizon is not at zero degrees. A body is conventionally said to rise when its upper limb touches the horizon. For the sun that happens when its centre is 0.833° below the horizon, because atmospheric refraction lifts the image by about 0.567° and the sun's own radius adds another 0.267°. The moon is close enough to Earth that a third effect dominates: horizontal parallax. Seen from the surface rather than from the centre of the Earth, the moon sits about 0.95° lower in the sky, so it has to be higher geocentrically before it appears on your horizon. The threshold works out to roughly 0.7275 × π − 0.5667°, or about +0.125° — a positive angle. Using the sun's −0.833° instead shifts every moonrise and moonset by around half an hour.

Some dates have no moonrise, and that is normal. Because the moon rises on average about 50 minutes later each day, a moonrise occasionally falls just after midnight and the next one just after the following midnight — leaving a calendar day with no moonrise at all. The same happens with moonset. Roughly once a month each, at every latitude. When it happens this tool says so in words rather than showing a blank, because a blank reads like a bug. In New York, for instance, 4 March 2026 has no moonrise and 19 March 2026 has no moonset.

Phase, illumination and age. The phase is set by the moon's elongation — its angular distance from the sun along the ecliptic. At 0° the moon is new, at 90° at first quarter, at 180° full and at 270° at last quarter. The illuminated fraction follows from the sun–moon–Earth phase angle, and is what the disc above is drawn from; the terminator is a half-ellipse, which is why a quarter moon has a perfectly straight edge and a gibbous moon a shallow curve. Age is the number of days since the last new moon, found by searching backwards for the instant of zero elongation rather than by dividing a mean lunation, so it stays correct even though the real synodic month varies by several hours either side of its 29.53-day average.

Distance and apparent size. The moon's orbit is noticeably elliptical: it ranges from about 356,500 km at perigee to 406,700 km at apogee, which changes its apparent diameter by roughly 14%. A full moon near perigee is the one popularly called a supermoon. Both figures are shown above for the date you pick.

At high latitudes the moon can be circumpolar. The moon's declination swings between roughly ±18° and ±28° over a month, so above about 62° latitude it can spend a whole date above the horizon — or a whole date below it — without rising or setting at all. This happens in both directions every month, unlike the sun's once-a-year midnight sun and polar night. The tool labels these dates explicitly.

Accuracy. Lunar position comes from the full periodic series in chapter 47 of Jean Meeus's Astronomical Algorithms — 60 longitude terms, 60 latitude terms and the planetary corrections — good to about 10 arcseconds. Checked against the US Naval Observatory across 232 rise, set and transit events spanning six locations from Reykjavík at 64°N to Sydney at 34°S, 220 matched to the exact displayed minute and the remaining 12 were one minute earlier; nothing disagreed by more than a minute. Times assume a flat, unobstructed sea-level horizon — hills, buildings and elevation will all shift what you actually see by considerably more than that.