Moon Phase Calculator
Choose any date — past, present, or future — to see its lunar phase.
Southern Hemisphere observers see the Moon's illuminated limb on the opposite side.
Select a Date to See the Moon Phase
Choose any date using the date picker and click Calculate Phase to see the lunar phase, illumination, cycle progress, upcoming phases, and practical guidance.
How to Use the Moon Phase Calculator
Select Your Date
Click the date picker and navigate to any date — past, present, or future. The calculator works for historical dates stretching back centuries and future dates many years ahead. Today's date is pre-filled by default so you can immediately see the current lunar phase.
Choose Your Hemisphere
Select Northern or Southern Hemisphere. Observers in Australia, South America, and southern Africa see the Moon's illuminated crescent on the opposite side compared to those in North America or Europe. This toggle adjusts the moon visual accordingly while keeping the phase calculations identical.
Read Your Results
The results show the phase name with a CSS moon visual, illumination percentage donut chart, cycle progress ring, moon age in days, and the direction (waxing or waning). If the selected date is a Full Moon, you'll see its traditional folk name and any special designations like Supermoon or Harvest Moon.
Use the Practical Guidance
Scroll down to see upcoming phase dates so you can plan ahead, along with lunar gardening advice tailored to the current phase and a fishing activity rating based on gravitational tidal influence. Export your results to CSV for record-keeping or use the Print button for a clean hard copy.
Frequently Asked Questions
How accurate is this Moon Phase Calculator?
Our calculator uses the Julian Day Number method with a precise reference New Moon (January 6, 2000 at 18:14 UTC), providing phase name and moon age accuracy within a fraction of a day for dates ranging from ancient history to the distant future. For everyday purposes — gardening, photography planning, curiosity — this level of accuracy is more than sufficient. For professional-grade astronomical work requiring sub-second precision (such as eclipse prediction or satellite tracking), specialized software using the full Jean Meeus polynomial corrections or JPL ephemeris data is recommended. The illumination percentage is computed using a cosine model that closely matches observed values.
What is a Supermoon and how rare is it?
A Supermoon occurs when a Full Moon (or sometimes New Moon) coincides with the Moon being at or near perigee — its closest orbital point to Earth. At perigee, the Moon is roughly 356,500 km from Earth, compared to the average distance of 384,400 km. The result is a Full Moon that appears about 14% larger and 30% brighter than a Full Moon at apogee (farthest point). Supermoons occur roughly 3 to 4 times per year and are visible to the naked eye, though the size difference is often subtle without side-by-side comparison. The term was coined by astrologer Richard Nolle in 1979, but astronomers now use it widely. Some years bring multiple consecutive Supermoons as the perigee and full moon alignment persists for several cycles.
Why does the Southern Hemisphere see the Moon differently?
Earth's orientation means that observers in the Southern Hemisphere are looking at the Moon from the opposite direction compared to those in the Northern Hemisphere. While the phase itself — the amount of illumination — is identical worldwide, the orientation of the illuminated limb appears mirrored. In the Northern Hemisphere, the Waxing Crescent appears as a D-shape with light on the right. In the Southern Hemisphere, the same phase looks like a reverse-D or C-shape with light on the left. Similarly, the Full Moon appears 'upside down' relative to what Northern Hemisphere observers see. Our hemisphere toggle flips the moon visual (rotating it 180°) to accurately reflect the Southern Hemisphere perspective.
What are the traditional Full Moon names and where do they come from?
Traditional Full Moon names were used by Native American tribes and colonial Americans to track seasons and natural events. January's Wolf Moon references the howling wolves heard in the cold winter nights. February's Snow Moon reflects the heavy snowfalls of that month. March's Worm Moon marks the thawing ground and returning earthworms. April's Pink Moon is named after the pink wildflowers (phlox) blooming in spring. May's Flower Moon and June's Strawberry Moon continue the seasonal theme. July's Buck Moon refers to deer growing new antlers. August's Sturgeon Moon honored the abundance of that fish in the Great Lakes. September through December complete the cycle with Harvest, Hunter's, Beaver, and Cold Moons.
Does the Moon phase really affect fishing and gardening?
The Moon's gravitational influence on ocean tides is scientifically established, and the same forces affect freshwater bodies and potentially even soil moisture. Many experienced anglers report peak fish activity during Full Moon and New Moon phases when tidal forces are strongest and fish are more active feeding. Scientific studies have shown some correlation, though local conditions, temperature, and season typically outweigh lunar influence. For gardening, the biodynamic tradition (developed by Rudolf Steiner) and various folk traditions advocate planting by Moon phase, with some modern horticultural research finding modest support for root and leaf development differences between lunar planting periods. Whether scientific certainty or respected tradition, millions of gardeners worldwide plan by the Moon.
What is the difference between a synodic month and a sidereal month?
A sidereal month (27.32 days) is the time it takes the Moon to complete one orbit of Earth relative to distant background stars — a true orbital period. A synodic month (29.53 days) is the time between two consecutive identical phases, such as Full Moon to Full Moon. The synodic month is longer because while the Moon is orbiting Earth, Earth itself is moving around the Sun. By the time the Moon returns to the same position relative to the stars, Earth has moved about 27° along its orbit, so the Moon must travel that additional angular distance to again align with the Sun-Earth geometry and produce the same phase. This is why we experience 12 or 13 Full Moons per calendar year rather than the 13 complete sidereal orbits.