Moon Phase Calculator
Result
Calculated result
0.7642926731
Based on the values entered.
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Moon Phase Calculator — free online calculator.
Formula
Moon age = (date − reference new moon) mod 29.53 days; illumination = (1 − cos(2π × age/29.53)) ÷ 2
- Moon Phase Calculator calculates its result from Age. It uses the formula Moon age = (date − reference new moon) mod 29.53 days; illumination = (1 − cos(2π × age/29.53)) ÷ 2. Change any input to recalculate the result instantly.
- The main inputs are Age. Enter them in the units and format shown in the calculator.
- Use the units, labels and assumptions shown beside each input so the formula is applied consistently.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Moon Phase
Inputs
- Age: 10
Using Age = 10, the calculated result is 0.7642926731.
Sample result: Calculating…
Frequently asked questions
What does the Moon Phase calculate?
Moon Phase Calculator — free online calculator.
Which values should I enter?
Enter Age using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Moon age = (date − reference new moon) mod 29.53 days; illumination = (1 − cos(2π × age/29.53)) ÷ 2.
Why might my result differ from another source?
Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.