This setting determines whether your winder does its job. It is also the one most people leave at the factory default.
What the TPD measures
TPD means turns per day. The number describes how many complete rotations the holder makes in twenty-four hours. These are not continuous: the device alternates short cycles and pauses, just as a wrist alternates movement and rest.
A winder set too low allows the watch's power reserve to run down gradually despite the device. Too high a setting does not damage it — modern slipping clutches limit mainspring tension — but makes the motor run unnecessarily.
The useful range
The majority of modern automatic calibres are between 650 and 1,000 turns per day. A few movements with a strong power reserve rise beyond.
This range is a guide, not a rule. Two watches from the same brand may use different calibres with different needs. The calibre matters, never just the name on the dial.
How to find the value of your watch
1. Identify the calibre. It often appears on the certificate, in the manual or engraved on the movement visible through a transparent caseback.
2. Look for the manufacturer's recommendation. Many manufacturers publish the recommended turns per day and winding direction for their calibres.
3. If not, ask your watchmaker. He knows the answer in seconds and it's free.
4. Do not rely on a generic chart per brand. These lists circulate everywhere and contain unreported exceptions.
The 48-hour test
Once the setting is set, the check is simple.
Set the watch using a reliable time reference, place it on the holder and let it run for forty-eight hours without touching it. Then compare the time.
If the watch is on time or very close, the setting works. If it has lost time or stopped, increase the setting by one step or switch from bidirectional mode to the single direction your calibre requires.
The direction of rotation
There are three modes: clockwise, counterclockwise and bidirectional.
Most movements wind in both directions using reversing gears. For these, bidirectional mode is the right choice because it distributes the load.
Some calibres, often older, only recharge in one direction. Leaving them in two directions divides efficiency by two: half the cycles are useless.
Several watches, several settings
This is why independent slots matter. If you alternate between three different calibres, one setting applied to all three will at best suit only one of them.
Our winders with two or more slots allow each slot to be programmed separately. See winders.
In summary
Identify the calibre, apply its recommendation, check for 48 hours, adjust if necessary. Four minutes of work for a device that then runs for years.
For the general principle of automatic winding, see our full guide.