How it works
Enter the requested values, review the input assumptions, and calculate the result. This is an approximation based on a simplified model. Real-world conditions, location, health, policy or source data can change the result.
Moon Phase Calculator
Estimate the moon phase, illumination, and upcoming major phases for any date.
Interactive calculator
This calculator becomes interactive when JavaScript is available. The page still provides its method, limits and related tools without JavaScript.
Result classification
Approximate. This is an approximation based on a simplified model. Real-world conditions, location, health, policy or source data can change the result.
Limitations
Treat the result as guidance, not a precise observation or professional assessment.
Frequently asked questions
How does this tool work?
This is an approximation based on a simplified model. Real-world conditions, location, health, policy or source data can change the result.
What should I verify?
Treat the result as guidance, not a precise observation or professional assessment.
Practical guide
Reviewed 27 July 2026How to use the Moon Phase Calculator
- Enter the known values.Use the date, time, place or duration requested above.
- Check the assumptions.Confirm time zone, weekend, inclusion and rounding choices when shown.
- Read and reuse the result.Copy, share or continue to a related tool without retyping unnecessary information.
Common uses
The Moon Phase Calculator is useful for outdoor planning, photography, calendars and observing the sky.
Edge cases to check
Pay particular attention to high latitudes, atmospheric refraction, terrain, weather and official religious announcements.