Introduction
The Moon changes shape in the sky every night. These shapes are called moon phases, and they follow a cycle that repeats about every 29.5 days. From a New Moon you cannot see, to a bright Full Moon, and back again — this pattern has been tracked by people for thousands of years.
This Moon Phase Calculator lets you find the exact moon phase for any date between the years 1700 and 2100. Pick a date, choose your country, and the tool will show you how much of the Moon is lit, where it sits in its cycle, and what phase it is in. You will also get a step-by-step breakdown of the math, a chart of daily illumination for the whole month, a visual lunar calendar, and a list of upcoming major phases like Full Moons and New Moons.
The calculator adjusts the moon image based on your hemisphere. If you live in the Southern Hemisphere, the lit side of the Moon appears flipped compared to the Northern Hemisphere. Just select your country and the tool handles the rest.
Whether you are planning a night hike, studying astronomy, working in a garden, or just curious about tonight's Moon, this tool gives you fast and clear answers.
How to Use Our Moon Phase Calculator
Enter a date and location below to find the moon phase for any day. The calculator will show you the phase name, how much of the moon is lit, the moon's age, a step-by-step solution, a monthly illumination chart, a lunar calendar, and a list of upcoming major phases.
Month: Pick the month you want to check from the dropdown menu.
Day: Pick the day of the month. The available days will update based on the month and year you chose.
Year: Pick any year from 1700 to 2100.
Your Country / Location: Choose your country from the list. This tells the calculator whether you are in the Northern or Southern Hemisphere, which changes how the lit side of the moon appears.
Hemisphere View: Leave this set to "Auto" to let your country decide the view. You can also pick "Northern" or "Southern" manually if you prefer.
Number of Phases to Display: Type a number from 1 to 99. This sets how many upcoming major moon phases (New Moon, First Quarter, Full Moon, and Last Quarter) the results will list.
Display Format: Choose "By Date" to see upcoming phases in order by date. Choose "By Phase" to group them by phase type.
Click the Calculate button to see your results. You can also press Today to jump to the current date or January 1st to jump to the start of this year. Press Reset to return all settings to their defaults.
What Are Moon Phases?
The Moon does not make its own light. It reflects light from the Sun. As the Moon orbits Earth, we see different amounts of its lit side. These changing shapes are called moon phases. A full cycle of moon phases takes about 29.5 days. This is called a lunar cycle, and you can use a date duration calculator to see how these cycles line up across months and years.
The Eight Moon Phases
There are eight main moon phases in each lunar cycle. They always happen in the same order:
- New Moon – The Moon sits between Earth and the Sun. The lit side faces away from us, so the Moon looks dark.
- Waxing Crescent – A thin sliver of light appears on the right side (in the Northern Hemisphere).
- First Quarter – Exactly half of the Moon's face is lit. The Moon has completed one quarter of its cycle.
- Waxing Gibbous – More than half is lit, and the bright area keeps growing.
- Full Moon – The entire face of the Moon is lit by the Sun. Earth sits between the Moon and Sun.
- Waning Gibbous – The light starts to shrink after the Full Moon.
- Last Quarter – The other half of the Moon is lit. Three quarters of the cycle are done.
- Waning Crescent – Only a thin sliver remains before the next New Moon.
"Waxing" means the lit area is growing. "Waning" means it is shrinking.
Why the Moon Looks Different in Each Hemisphere
People in the Northern Hemisphere and Southern Hemisphere see the Moon flipped. In the north, the lit side of a waxing moon appears on the right. In the south, it appears on the left. The phase is the same — only the view changes based on where you stand on Earth.
How Moon Illumination Is Calculated
The percentage of the Moon's face that is lit is called illumination. At a New Moon, illumination is 0%. At a Full Moon, it is 100%. Astronomers figure this out by measuring how far the Moon has traveled through its 29.5-day cycle. The Moon's age in days tells us its position in the cycle, and a simple formula converts that position into a percentage. Behind the scenes, this calculator converts your chosen date into a Julian Date — a continuous day count used in astronomy — to perform these calculations precisely.
What Is the Moon's Zodiac Sign?
As the Moon orbits Earth, it passes through the twelve zodiac constellations. It spends roughly two to three days in each sign. The Moon's zodiac position is based on its location along the ecliptic, which is the path the Sun appears to follow across the sky. This calculator shows which zodiac sign the Moon is in on your chosen date. For a deeper look at what the Moon's sign means for you personally, try our Moon Sign Calculator. You can also explore your full birth chart or discover your Chinese Zodiac sign for additional celestial insights.