A high-end replica Patek Philippe perpetual calendar 3940 should copy the original 36mm Calatrava case, the center date hand, and the day and month subdials at 3 and 9 o'clock. Many copies use a basic triple-calendar module that cannot handle 30-day months. Test the date change on March 1, measure the case, and inspect the moonphase before you pay.

What Does the Genuine 3940 Chronometer Contain?

The Patek Philippe 3940 is a perpetual calendar watch with a moonphase and a 48-month program. It ran from about 1985 through the mid-2000s, powered by the self-winding caliber 240Q.

The 240Q movement is only about 3.9mm thick, which is why the watch case stays around 36mm wide and under 10mm thick. The dial has a long center hand that points to a date ring around the edge. Day and month sit in two subdials. The moonphase aperture is above the six o'clock marker.

What Are the Common Movement Platforms in a Replica 3940?

No affordable replica uses a true clone of the 240Q. Instead, manufacturers take a standard automatic movement and bolt on a calendar module.

• Miyota 9015 with a day, date, and month module, common in mid-tier replicas.
• Asian 2892 clone with an add-on perpetual module, seen in higher-grade pieces.
• Seagull manual wind movement in a few rare no-autowind versions.

Ask the seller exactly which movement sits inside. If they say only "automatic," that is a red flag. The movement base determines how accurately the calendar shifts.

How Do You Test a Replica 3940 Perpetual Calendar?

Set the watch to March 1 and wait for the date change. A real perpetual calendar moves to March 1 after February 28, and to February 29 in a leap year. Many replicas change on a fixed 31-day cycle, so they show 31 on 30-day months.

Turn the crown to set the date hand backward. On a genuine 3940, the calendar mechanism tolerates backward setting. On a low-grade copy, forcing the date backward can strip the gear and leave the date hand floppy.

Dial Check: Day, Month, and Date Hand Placement

The genuine 3940 places the day register at 9 o'clock and the month at 3 o'clock. The date scale runs along the flange, and the central date hand reaches every numeral without bending.

Look at the subdial hands. Genuine examples have thin hands that point to the full printed index. Replica dials often show fat hands that stop short of the track, which makes the watch look clumsy. Check for open gap between the registers and the minute track too.

What Are the Biggest Moonphase Mistakes?

Moonphase is the easiest tell on a replica 3940. The genuine moonphase disk has a starry upper half and a gold moon that crosses a clean horizon. Many replica disks are flat prints that look like a yellow sticker.

Set the crown to the moonphase adjustment position and click it forward. The moon on a real 3940 moves in small incremental steps. A replica that jumps in large increments or moves two moons at once points to a cheap calendar module.

How Do You Judge the Case Size and Crown Quality?

Measure the case width. The reference 3940 is around 36mm, and that short lug-to-lug distance lets it slide under a dress cuff. A replica that measures 40mm or 42mm uses the wrong case geometry.

Check the crown when you wind it. A smooth mainspring feels consistent and silent. A rough or gritty winding feel, or a crown that wobbles, indicates a generic stem and a low-end movement.

Strap, Lugs, and Clasp Checks

Most 3940 watches come on a leather strap with a deployant clasp. The lug width on the genuine model is 18mm. If the replica strap is 20mm wide, the case is a modified 5227 or 5140 case, not a real 3940 form.

Use a loupe to inspect the engraving on the clasp. Genuine Patek Philippe deployment buckles carry crisp lettering with a defined cross. On replicas, the engraving may have shallow edges or a rougher background.

How Much Does a Good Replica 3940 Cost?

A working 3940 replica with a reliable Miyota or Asian 2892 movement sells for $300 to $700. Under $200, you get bad dial spacing, a short calendar life, and a wobbly crown.

Some niche suppliers ask more than $800 for a 3940 with a decorated movement. Those rare versions try to imitate the Geneva stripes on the 240Q. Still, no copy below $1,500 gives you a real 48-month program.

Is the Replica 3940 Worth Buying for a First Perpetual Calendar?

A replica 3940 works well if you want the vintage Calatrava look and the center date hand. It does not work as a true perpetual calendar. Most copies only shift the date and moonphase for 31 days, then you reset them.

For a first Patek replica, a 3940 with a simple calendar module teaches you how these watches feel on the wrist. Just know the limitation: you can buy a perpetual calendar look, but you are not getting the leap-year brain.

Frequently Asked Questions about the Replica Patek 3940

Does the 3940 replica have a leap-year indicator?

The genuine 3940 has a small four-cycle year window somewhere on the dial, often near the six o'clock subdial. Many replicas skip this indicator or print it as decoration. Press the month corrector and watch whether the year wheel advances at the end of each cycle. If it does not move, the watch is not a real perpetual calendar.

What is the difference between the 3940 and the 5140 replica?

The 5140 replaced the 3940 in the Patek catalog with a slightly larger 37mm case. Replicas of the 5140 are more common and have more factory support. The 3940 replica usually comes from smaller workshops, so inspect every part with extra care.

Can you swim with a replica 3940?

No. The genuine vintage 3940 is not a dive watch and has limited water resistance. A replica with the case back pressed in and the crown pushed in may survive a splash, but use it as a dress piece only.