Moon Phase Timing
Estimate the moon phase age and days to the next full or new moon.
About Moon Phase Timing
Measuring the time since a known new moon and reducing it by the synodic month gives the lunar phase age and days to key phases. Moon phase timing matters for astronomy, gardening and anyone who likes to sync activities to the lunar cycle.
Formula
Moon Phase Timing
Phase age = days since the nearest known new moon, modulo the synodic month (29.53 days)
- synodic month
- The 29.53-day cycle between new moons
Worked example
With the default values below, Moon Phase Timing returns Phase Age (Days) of 21m. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Year
- 2,025
- Monthaccepts 1–12
- 8
- Dayaccepts 1–31
- 15
Results
- Phase Age (Days)
- 21m
- Phase
- Last Quarter (approx)
- Days to Full Moon
- 23m
Step by step
- 1Values used
- 2Moon Phase Timing
- 3Phase Age (Days)= 21.49
- 4Phase= Last Quarter (approx)
- 5Days to Full Moon= 22.81
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Moon Phase Timing calculated?
Phase age = days since the nearest known new moon, modulo the synodic month (29.53 days) Measuring the time since a known new moon and reducing it by the synodic month gives the lunar phase age and days to key phases.
Why does Moon Phase Timing matter?
Moon phase timing matters for astronomy, gardening and anyone who likes to sync activities to the lunar cycle.
What values do I need to enter?
This calculator takes 3 inputs: Year, Month, Day. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.