Sub-dial
A sub-dial is a small auxiliary dial set into the main dial of a watch. It is used for chronograph counters, a running seconds display, a pointer day or date, or a second time zone. By keeping that information separate, it adds function without cluttering the main time readout.
At a glance
- Also called
- Subdial, register, counter
- Common use
- Chronograph counters, running seconds
- Typical count
- Two or three on a chronograph
A sub-dial carries its own scale without sharing the surface of the main dial. It may have a tiny hand of its own, or it may simply be a register read against printed markings. The point is to give one piece of information its own space and keep it out of the path of the main hands.
What it does
You will see it handle a few common jobs:
- Chronograph counters: they total the elapsed minutes and hours on separate registers
- Running seconds: moves the seconds hand off center onto its own small display
- Second time zone: adds an extra 12 or 24 hour scale
A chronograph usually carries two or three sub-dials, and that layout gives the face a balanced symmetry.
Where it sits in design
Sub-dials directly affect how legible the dial is. Placed well, they clarify the information; placed poorly, they crowd the main hands. For more terms on this part of the watch, see the Dial and Hands section.
To see sub-dials in practice, look at the chronograph models in our guide to the best Seiko watches.
Examples
On a blue-dial quartz chronograph, the sub-dials show the chronograph minute counter, a 24-hour indicator and running seconds on separate registers, so the main hands stay easy to read.
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Comparison
A sub-dial and an aperture solve the display differently.
| Option A | Option B | Notes |
|---|---|---|
| Sub-dial | Aperture window | A sub-dial works with its own scale and usually a small hand; an aperture shows a number or disc through a cutout in the main dial. |
Related terms
Watches that show this
Frequently asked questions
What is a sub-dial used for?
A sub-dial keeps one piece of information separate from the main dial. Its most common jobs are chronograph counters, a running seconds display, a pointer day or date, and a second time zone. This keeps the main hands clear and easy to read.
How many sub-dials does a chronograph have?
Most chronographs carry two or three sub-dials. They typically count elapsed minutes and hours, with one showing running seconds. The exact number and placement depend on the movement inside and the design choice of the watch.
Is a sub-dial the same as an aperture window?
No, they differ. A sub-dial has its own scale and usually a small hand that sweeps it. An aperture is a cutout in the dial that shows a number from a disc beneath it, as a date window does. They serve the layout in different ways.