A moon phase calculator shows which phase the moon is in for any given date. The lunar cycle lasts approximately 29.53 days, cycling through eight distinct phases from New Moon to Full Moon and back. Enter a date below to see the phase name, illumination percentage, visual moon display, and upcoming lunar events.
Select a Date
Upcoming Major Phases
Monthly Moon Calendar
How to Use the Moon Phase Calculator
The moon phase calculator lets you instantly see what phase the moon is in for any date. Whether you are planning a night photography session, scheduling a fishing trip, or simply curious about tonight's sky, this tool gives you accurate lunar data including the phase name, illumination percentage, and a visual representation of the moon.
Step 1: Select a Date
The calculator automatically shows today's moon phase when you load the page. To check a different date, use the date picker at the top. You can look up any date in the past or future. Click the "Today" button to quickly return to the current date.
Step 2: Read the Moon Phase
The large visual moon display shows a realistic representation of the moon's current illumination. Below it, you will find the phase name (such as Waxing Crescent or Full Moon) along with its emoji symbol. The stats cards show the illumination percentage, moon age in days since the last New Moon, cycle progress, and days until the next Full Moon.
Step 3: Check Upcoming Phases
The upcoming phases section shows the dates of the next four major lunar phases: New Moon, First Quarter, Full Moon, and Last Quarter. This is useful for planning activities that depend on moonlight levels, such as stargazing (best around New Moon) or outdoor photography (best around Full Moon).
Step 4: Browse the Monthly Calendar
The monthly calendar at the bottom shows a moon emoji for every day of the month. Use the arrow buttons to navigate between months. This gives you a quick overview of how the moon phase changes throughout the entire month, making it easy to spot Full Moon and New Moon dates at a glance.
Understanding the Lunar Cycle
The moon completes one full cycle approximately every 29.53 days. Starting from the New Moon (0% illumination), it waxes through Crescent and Gibbous phases to Full Moon (100% illumination), then wanes back through Gibbous and Crescent to the next New Moon. The First Quarter and Last Quarter phases occur at roughly the halfway points, when the moon appears half-lit.
Frequently Asked Questions
Is this moon phase calculator free?
Yes, the Moon Phase Calculator is completely free with no limits. Check the moon phase for any date as many times as you want. No signup, no account, and no premium features behind a paywall.
Is my data safe and private?
Absolutely. All calculations run entirely in your browser using JavaScript. No data is sent to any server, stored in any database, or shared with anyone. When you close the page, everything is gone.
How accurate is this moon phase calculator?
This calculator uses a simplified astronomical algorithm based on the known lunar cycle of 29.53 days. It is accurate enough for general reference, gardening, fishing, and casual astronomy. For precise scientific calculations, consult an ephemeris or NASA data.
What are the eight moon phases?
The eight phases are New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, and Waning Crescent. Each phase lasts roughly 3.7 days as the moon completes its 29.53-day cycle.
What does moon illumination percentage mean?
Moon illumination is the percentage of the moon's visible surface that is lit by the sun as seen from Earth. At New Moon it is 0%, at Full Moon it is 100%, and at the Quarter phases it is approximately 50%. The value changes continuously throughout the lunar cycle.
How long is a lunar cycle?
A complete lunar cycle, also called a synodic month, is approximately 29.53 days. This is the time it takes for the moon to go from one New Moon to the next. The cycle length varies slightly each month due to the moon's elliptical orbit.
Can I check the moon phase for a past or future date?
Yes. Use the date picker to select any date in the past or future. The calculator will show the moon phase, illumination percentage, moon age in days, and the nearest upcoming major phases from that date.
Why do farmers and gardeners track moon phases?
Many traditional farming and gardening practices follow lunar cycles. Some gardeners plant above-ground crops during the waxing moon and root crops during the waning moon. While scientific evidence is limited, moon phase tracking remains a popular practice for garden planning.