Dates & time

Moon phase calculator

The Moon's phase and illumination on any date, with the next full and new moons.

Embed this calculator on your website

Copy this code and paste it into your page (WordPress, Wix, Webflow, HTML…). It's free: please keep the link to HOD Calc.

<iframe src="https://calc.hod-group.com/embed/?hodtool=moon&amp;hodlang=en" title="Moon phase calculator" loading="lazy" style="width:100%;max-width:720px;height:560px;border:0;border-radius:12px" data-hodcalc></iframe>
<p style="font:13px sans-serif;margin:6px 0 0">Calculator by <a href="https://calc.hod-group.com/en/moon-phase-calculator/">HOD Calc</a></p>
<script async src="https://calc.hod-group.com/assets/embed.js"></script>

How it works

Moon age = days since a reference new moon (6 January 2000) modulo 29.53 days (synodic month). Accuracy: about one day.

Results are for guidance only and do not replace professional advice.

Worked example

With the default values:

Date31 October 2026

you get:

PhaseWaning gibbous 🌖
Illumination71 %
Moon age20.1 days
Next full moonTuesday, 24 November 2026

Frequently asked questions

How does the “Moon phase calculator” tool work?

Moon age = days since a reference new moon (6 January 2000) modulo 29.53 days (synodic month). Accuracy: about one day.

What do I need to enter?

Just fill in: date. The result updates as you type.

Can you give an example?

Date: 31 October 2026 → Phase: Waning gibbous 🌖; Illumination: 71 %.

Is this calculator free, and is my data private?

Yes. HOD Calc is completely free with no sign-up. The calculation runs in your browser: nothing you type is sent or stored.