A moonphase display shows the current shape of the moon in a small window on the dial. It runs on its own once set, but after a battery change, a few days in a drawer or a new purchase, you will need to set it. It takes about two minutes. Here is how.
What you need
- Your watch
- The date of the most recent full moon (search “moon phase today” or use any moon calendar app)
- The manual for your model. All Valuchi manuals are on our watch manuals page
Step 1: Check the time first
Look at the time on the watch. If it shows between roughly 9 pm and 3 am, move the hands to midday before you change anything. In this window the calendar wheels are already engaged for the overnight change, and forcing them can damage the mechanism. Most watchmakers call this the “danger zone”.
Step 2: Set the moon to full
Use the moonphase corrector (a small recessed pusher in the case side) or the crown position described in your manual. Advance the moon disc until the full moon sits exactly centred in the window. This is your reference point.
Step 3: Count the days since the last full moon
Look up the date of the most recent full moon and count how many days have passed since then. For example, if the last full moon was on the 5th and today is the 12th, that is 7 days.
Step 4: Advance one click per day
Press the corrector (or turn the crown) once for every day you counted. Each click moves the disc forward by roughly one day of the lunar cycle. After 7 clicks in our example, the moon will show a waning shape, matching the real sky.
Step 5: Set the date and time
Now set the date, day and time as usual. If your watch has a date, make sure it changes at midnight and not at noon: wind the hands past 12 and check whether the date jumps. If it jumps, you are in the morning; continue to the correct time.
Common mistakes
- Starting from the new moon. The new moon is shown as an empty window and is harder to judge. The full moon is centred and easy to align.
- Correcting in the danger zone. Always move the hands to midday first.
- Counting from the wrong full moon. The cycle is about 29.5 days, so if you count more than 29 days, you missed a more recent full moon.
How accurate is a moonphase?
A lunar month lasts 29 days, 12 hours and 44 minutes. Most moonphase watches use a 59-tooth disc that advances once a day and shows two moons per rotation, giving a cycle of 29.5 days. That small difference adds up to about one day of error every two and a half to three years, so an occasional single click keeps it perfect. Want the full background? Read what a moonphase watch is and how it works.
Valuchi moonphase watches
Moonphase displays appear on the Lunar Calendar and Lunar Calendar Automatic, the Dual Calendar 40mm, the square Expedition and the women’s Clouds Edition. For model-specific instructions, see the Lunar Calendar manual, Lunar Calendar Automatic manual and Dual Calendar manual.
