2026-09-14 9 min

Moon Phase Calculator

Find the moon phase for any date — phase name, illumination, moon age, and countdowns to the next full and new moons.

Calculator

Date

Results update automatically

Results update live as you type

Status:Full Moon100.0% litFull 2026-10-26 (0d)

Moon Summary

PhaseFull Moon (full)

Illumination100.0%

Moon age14.6 / 29.53 days

Next full / new2026-10-26 / 2026-11-09

DirectionWaxing

Lunation Progress

Illumination100.0%

Cycle position14.6 / 29.53 days

To full moon0.1 days

Breakdown

Measure	Value
Phase detail	Full Moon (full)
Next full (in)	2026-10-26 (0.1d)
Next new (in)	2026-11-09 (14.9d)
Direction	Waxing
Cycle progress	49.5%
Date checked	Monday, October 26, 2026

Results

Optimal

Moon Phase

Full Moon

One of 8 phases (full)

Illumination

100.0%

Lit fraction of the visible disc

Moon Age

14.6 days

Days since the last new moon

Direction

Waxing — growing

Toward full or toward new

Next Full Moon

2026-10-26

In 0.1 days

Next New Moon

2026-11-09

In 14.9 days

Cycle Progress

49.5%

Share of the 29.53-day lunation

Date

Monday, October 26, 2026

Checked date in long form

Synodic-month arithmetic from the Jan 6, 2000 new-moon reference. Phase and illumination within ~1 day; exact instants need ephemeris data.

Visualizations

Lunation Quarters (days)

7.4dNew→1st

7.4d1st→Full

7.4dFull→Last

7.4dLast→New

Illumination

Lit100%

Moon Age vs Lunation

Age14.6

Formula

The synodic month (new moon to new moon, 29.53 days) is the lunar clock; phase angle within it drives both the name and the lit fraction.

Age = (date − ref) mod 29.53; lit = (1−cos(2π·age/29.53))/2

Alternative Form

Phase index = floor(age/29.53 × 8 + 0.5) mod 8

Variables

Symbol	Name	Unit	Description
R	Reference new moon	UTC	Jan 6, 2000 18:14 UTC
S	Synodic month	29.53 d	New-to-new period
A	Moon age	days	Position in lunation
I	Illumination	%	Lit fraction of disc

Explanation

Sun–moon geometry repeats every synodic month (longer than the 27.3-day orbit because Earth moves too); cosine of the phase angle gives the lit share.

Derivation

A = (D−R) mod S; idx = floor(A/S×8+0.5) mod 8; I = (1−cos(2πA/S))/2; full at 14.765, new at 29.53.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Count days since the reference new moon (Jan 6, 2000).

Elapsed = (date − reference) in days

Date:2026-10-26

Intermediate: Astronomical anchor point

Result: 14.6 days into the cycle

Step 2

Wrap into one 29.53-day lunation for the moon age.

Age = elapsed mod 29.53058867

Moon Age:14.6 days

Intermediate: Position on the lunar clock

Result: Day 14.6 of 29.53

Step 3

Name the phase from eighths of the cycle.

Index = floor(age ÷ 29.53 × 8 + 0.5) mod 8

Phase:Full Moon

Intermediate: 8 named phases around the clock

Result: Full Moon

Step 4

Compute illumination from the phase angle.

Lit = (1 − cos(2π × age ÷ 29.53)) ÷ 2

Illumination:100.0%

Intermediate: 0% new, 100% full, 50% quarters

Result: 100.0% lit

Step 5

Read waxing vs waning from the half.

Waxing ⟺ age < 14.765

Direction:Waxing

Intermediate: Growing toward or shrinking from full

Result: Growing to full

Step 6

Project the next full and new moons.

Full at age 14.765; new at 29.53

Next Full:2026-10-26 (0.1d)

Next New:2026-11-09 (14.9d)

Intermediate: Within ±1 day without ephemeris

Result: Full 2026-10-26 · new 2026-11-09

Final Answer

Full Moon

Worked Examples

See how the calculator works with different scenarios.

Scenario

September 14, 2026.

Inputs

Date:2026-09-14

Calculation

Age ≈ 22.4 → Waning Crescent, ~22% lit

Result

Waning Crescent heading to new

Interpretation

Thin morning crescent — dark skies for stargazing.

Understanding Your Result

Your Result: Moon Phase: Full Moon

Typical range: Full moons recur every ~29.5 days (~12.4/year); illumination sweeps 0–100% sinusoidally.

What This Means

Phase name plus illumination describes the night sky; age positions the cycle; full/new countdowns schedule around moonlight.

Why It Matters

Launches, shoots, fishing, and festivals all ride moonlight. ±1-day accuracy suffices for every one of them.

Professional Interpretation

Photographers chase golden-plus-full alignments; astronomers avoid full weeks for deep-sky work.

Recommendations

•Plan shoots near full dates
•Stargaze on new weeks
•Verify exact instants via ephemeris
•Pair with Golden Hour for light
•Check tides near full/new

Educational Content

Introduction

The Moon Phase Calculator renders any date's lunar position: name, lit fraction, age, direction, and full/new countdowns.

Concept Explanation

Synodic-month position drives an 8-phase name and a cosine illumination curve; full sits at 14.765 days, new at 29.53.

Applications

▸Planning night photography

▸Timing launches and events

▸Predicting spring tides

▸Scheduling stargazing

▸Following cultural calendars

Benefits

•Instant any-date phases
•Countdowns to full/new
•Stargazing guidance
•Tide intuition

Limitations

•±1 day without ephemeris
•No eclipse prediction
•No moonrise times

Best Practices

•Confirm exact instants via USNO
•Shoot ±1 day around full
•Stargaze within days of new
•Pair with weather forecasts

Common Misconceptions

Myth: Full moons last all night.

Truth: Peak illumination spans ~a day; nearby nights look nearly full too.

Myth: The dark side is unlit.

Truth: The far side gets equal sun — phases are viewing geometry, not shadows.

Myth: Moon calendars predict eclipses.

Truth: Phases are necessary but not sufficient — nodes must align too.

Practical Tips

•Shoot around full ±1 day
•Stargaze near new
•Check tides at full/new
•Pair with clear skies
•Verify instants via USNO
•Track monthly rhythm
•Pair with Golden Hour

Common Mistakes

Expecting to-the-minute full

This is ±1 day — ephemerides give instants.

Ignoring weather

Clouds beat moon math every time.

Confusing waxing/waning

Waxing grows to full; waning shrinks to new.

Planning eclipses here

Phases don't predict eclipses — nodes do.

Assumptions

This calculator makes the following assumptions to provide estimates:

Synodic Clock: 29.53058867-day lunation.

Reference New: Jan 6, 2000 18:14 UTC.

UTC Dates: Whole-day positions.

±1 Day: No perturbation modelling.

Limitations

Be aware of these limitations when using this calculator:

No Ephemeris: Perturbations unmodelled.

No Eclipses: Node geometry excluded.

No Rise Times: Moonrise needs location math.

Frequently Asked Questions

Answers to common questions about this calculator.

What phase is the moon in tonight?

Enter today's date: phase name, illumination, and age describe tonight's sky within about a day.

When is the next full moon?

The countdown gives the date and days-to-full — plan shoots and tides around it ±1 day.

Why is illumination a curve, not linear?

Lit fraction follows the cosine of the sun–moon phase angle — slow near new/full, fast at quarters.

Waxing vs waning?

Waxing (age < ~14.8) grows toward full; waning shrinks toward new. Evening vs morning visibility follows.

Can it predict eclipses?

No — eclipses need lunar-node alignment beyond phase position.

How accurate are the dates?

Within about a day. For to-the-minute full/new instants consult USNO or ephemeris tables.

How accurate are these date calculations?

All math uses UTC midnight-to-midnight day arithmetic, so daylight-saving shifts never add or remove an hour from a day count. Results are exact for the Gregorian calendar for any date from 1900 through 2100.

Do leap years affect the result?

Yes, automatically. February 29 exists in leap years (divisible by 4, except centuries unless divisible by 400), and every total-days figure in this calculator counts it exactly.

Why do months give uneven results?

Months are 28 to 31 days long, so converting days to months is approximate. This calculator reports exact years, months, and days using calendar arithmetic, plus exact totals in days, weeks, and hours so nothing is hidden by rounding.

Which time zone is used?

Dates are parsed and compared in UTC to keep results identical in every time zone. Enter the calendar date as written; the exact hour of day is not modelled unless a time field is shown.

What date format should I enter?

Use the date picker or YYYY-MM-DD format, for example 2026-09-14. The calculator validates February 30 and similar impossible dates and falls back to today when a field is empty.

Can the end date be before the start date?

If the dates arrive reversed, the calculator swaps them internally and still reports a positive span, so the breakdown always describes the true distance between the two dates.

How does the Moon Phase Calculator estimate sunrise and sunset?

It combines date, latitude and longitude with solar declination and standard refraction for the visible limb. Results are good within minutes for planning; official tables govern navigation.

Why do sunrise times change with latitude and season?

Higher latitudes tilt more toward or away from the sun, stretching summer days and shrinking winter days. Near equinoxes day and night balance near 12 hours everywhere.

What are golden hour, blue hour, dawn, dusk and twilight?

Golden is warm low sun just after rise and before set, blue is indirect light when sun is 4 to 8 degrees below horizon, and dawn/dusk bookend twilight phases. Photographers plan shoots on those windows, not noon.

What is solar noon and how is it different from clock noon?

Solar noon is when the sun peaks for your longitude, which can differ an hour or more from 12:00 due to zone width and DST. The Moon Phase Calculator reports solar noon separately from civil noon.

How does daylight saving affect sunrise wall times?

DST shifts wall clocks one hour without moving actual solar events, so sunrise reads an hour later by the clock in summer. Compare solar spans for true daylight and wall times for alarms.

How accurate are moon phase and moon age estimates?

Phase from synodic 29.53-day math is accurate within a day for casual use, with full and new moons flagged to the nearest date. Telescope planning should confirm with an ephemeris for exact illumination.

What causes polar day and polar night?

Above the Arctic or below the Antarctic circle the sun can stay up or down 24 hours near solstices. The Moon Phase Calculator flags those no-rise or no-set cases instead of forcing a time.

How do equinoxes and solstices relate to daylight hours?

Equinoxes near Mar 20 and Sep 22 balance day and night, June solstice maximizes northern daylight, December minimizes it. Daylight-hours peaks and troughs align to those four dates.

Can I use the Moon Phase Calculator for any city worldwide?

Yes with latitude and longitude or city selection, because solar geometry needs position. Coastal versus mountain horizon and elevation shift visible times by minutes.

How should photographers use golden and blue windows?

Arrive 30 minutes before golden start for setup and stay through blue for city lights. The Moon Phase Calculator duration of each window guides battery, lens and permit planning.

Why do official tables sometimes differ by a few minutes?

Different refraction, horizon elevation and rounding conventions move results slightly. Treat calculator times as planning estimates and confirm critical events with the local observatory table.

How are lunar dates and religious calendars handled?

Lunar months average 29.53 days with observation and regional rules shifting start by a day. Use the Moon Phase Calculator for approximation and the authoritative religious calendar for observance.

What is the difference between next full moon and next new moon?

Full is fully lit opposite the sun, new is dark near the sun, spaced about 14.77 days apart. The countdown targets the next occurrence after today, not the current phase age.

How do clouds, elevation and horizon affect viewing?

Low horizons and altitude advance rise and delay set by minutes, while clouds can obscure short twilight windows entirely. Build a 15-minute buffer around the listed time outdoors.

How can I archive a shoot plan with sun and moon times?

Save date, location, sunrise, sunset, golden, blue and moon phase together with time zone. The crew can then verify solar noon plus half daylight equals sunset.

Is the Moon Phase Calculator free for shoot and trip planning?

Yes, free with no sign-up on any device. Bookmark locations and re-run per date for scouting without extra apps.