Moon Phase Date Calculator

Explore an approximate lunar phase from a published mean synodic-month model.

Estimated Moon Phase
First Quarter
Phase age 8.62 days
Estimated illumination 63.0%
Model period 29.530588853 days
Inputs
Enter a UTC calendar date; this simplified model is approximate.
Results & Graph
Estimated Moon Phase
First Quarter
Phase age
8.62 days
Estimated illumination
63.0%
Model period
29.530588853 days

Estimated Moon Phase Calculation

Graph 1 • Moon Phase Date • Domain Architecture & Live Telemetry Maps Date (UTC) through Calculation Method.
Moon Phase Date Calculator • Mathematical Topology (Calculation Method) targ • Date (UTC) 1 ASTROLOGY & SKY CY Phase age = modulo(day moon-phase-date-calc ESTIMATED MOON PHASE First Quarter • Phase age: 8.62 days • Estimated illumination: 63.0% • Model period: 29.530588853 da
Graph 2 • Estimated Moon Phase Across Input Sweep (40% → 160%) Evaluates Phase age = modulo(days from 2000-01-06 18:14 UTC, 29.530588853); illumi across 7 operating points (current input highlighted).
0 illumi 0.550 illumi 1.10 illumi 0 4 0 6 0 8 0 10 0 12 0 14 0 16
Graph 3 • Moon Phase Date Multi-Scenario Envelope Shows how Estimated Moon Phase responds across ±30% scenario shifts.
0 illumi 0.550 illumi 1.10 illumi 0 -30% 0 -15% 0 +0% 0 +15% 0 +30%
Summary: A mean lunar month model estimates phase age 8.62 days and illumination 63.0%. It is not an exact ephemeris.
Summary: A mean lunar month model estimates phase age 8.62 days and illumination 63.0%. It is not an exact ephemeris.
⚡ Chain Result (First Quarter) To: Personal Year & Month (Calendar Year) →
Interactive chart & math engine powered by CalculatorGraph

Formula & Mathematical Methodology: Calculation Method

Phase age = modulo(days from 2000-01-06 18:14 UTC, 29.530588853)
illumination ≈ (1−cos(2π age/period))/2.
Phase age = modulo(days from 2000-01-06 18:14 UTC, 29.530588853); illumination ≈ (1−cos(2π age/period))/2.
  • targetDate: User-entered date (utc).

Rounding: Integer digit sums are exact; lunar phase is an approximation.

Worked Example: Example: Moon Phase Date

Explore an approximate lunar phase from a published mean synodic-month model.

  1. Enter the date, name, or number shown.
  2. Review the method and its convention.
  3. Inspect the calculation steps and supporting values.
Result: Results depend on the selected tradition and should be treated as interpretive entertainment.

Frequently Asked Questions

Are these results scientifically validated predictions?

No. Numerology and astrology interpretations are cultural or spiritual practices; the tools do not validate predictions about a person or future event.

Why can results differ between calculators?

Traditions may use different letter mappings, digit-reduction order, master-number rules, date boundaries, or astronomical models. This page states its chosen convention.

Astrology & Numerology · Astrology & Sky Cycles

Moon Phase Date Calculator: inputs, method, and how to read the result

Explore an approximate lunar phase from a published mean synodic-month model.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Date (UTC): Enter a UTC calendar date; this simplified model is approximate.

What the calculation includes

With the default values shown, Estimated Moon Phase is First Quarter. The calculation follows Calculation Method; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Date (UTC) from 2026-10-20 to 2026-10-21 changes Estimated Moon Phase from First Quarter to Waxing Gibbous. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • These tools describe numerology or astrology traditions; they do not make scientifically validated predictions.
  • The mean synodic-month model is approximate and is not an ephemeris; do not use it for observation planning or exact astronomical events.

Scope: Interpretive tradition or simplified astronomical approximation; see method and limitations Check the assumptions and limitations against your situation before relying on the estimate.

More in Astrology & Numerology: Life Path Number Calculator, Name Numerology Calculator, Personal Year and Month Numerology Calculator.