Moon Phase Calculator
Calculate the current or any date's moon phase.
What is Moon Phase?
A moon phase calculator based on the synodic month. Pick a date and see the phase name, illumination, and days into the cycle.
How it works
The phase is derived from the date's position in the 29.53-day synodic cycle, referenced to a known new moon epoch.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Phase on a given night
See the moon phase for any date — New, First Quarter, Full, Last Quarter with illumination percentage — for stargazing or photography planning.
Common mistakes
Phase names vs illumination
Waxing and waning describe the trend, not the amount. 50% illumination can be either First or Last Quarter depending on the direction.
Frequently asked questions
Is the phase the same everywhere on Earth?
Essentially yes — the phase is a global event; only the local clock time of moonrise differs by location.
What do waxing and waning mean?
Waxing means the illuminated portion is growing toward Full; waning means it is shrinking after Full.
Can I find the next full moon?
Yes — the tool lists upcoming full and new moon dates from any starting date.