Moon Phase Calculator

Moon phase here is an astronomical cartoon from a known new-moon epoch (6 January 2000 UTC) and a 29.53058867-day synodic month. 17 September 2026 lands in a waxing-crescent sketch at about 32% illumination in this model. It is not a Panchang, not a karwa chauth timetable, and not an astrologer’s clock.

A short pause

Photographers in Leh and festival planners who only need “is it a bright night?” can use a civil phase. Vedic tithi can disagree with this western illumination model around the edges. IndiaKit says so instead of selling a muhurat.

What this widget does

Age of moon = days since the epoch modulo synodic month. Bins: new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter, waning crescent. Default date 2026-09-17.

Illumination ≈ 50 − 50 × cos(2π × age / period), as a percent sketch.

Eclipse predictions and IST festival dates need IMD / positional astronomy / an official Panchang, not this page.

17 September 2026, waxing crescent sketch

A photographer types 2026-09-17 and sees waxing crescent at about 32% illumination in the model. She still checks a sky app for moonrise in Leh because phase is not altitude.

Not indexed as the product

Approximate phase, not tithi. Not religious timing. Epoch-based, not JPL Horizons. Entertainment / planning sketch.

Common questions

Will this match my city’s Panchang tithi?

Not always. Tithi is a lunar-day in a different system. This page is illumination phase in a synodic-month model.

Can I use it for karwa chauth moonrise?

No. You need local moonrise from a proper ephemeris or an official announcement. Phase ≠ rise time.

Why 17 September 2026 as default?

It is a sample date near when this copy was written, so the screenshot of the tool had a real phase to talk about.