377 battery equivalents
The 377 is a 6.8 × 2.6 mm silver-oxide cell, used in small quartz watches, including many women's and dress watches. It's sold under several names: SR626SW, SR626W, 376, LR626, AG4, 177, LR66, SR66.
Equivalents
| Sold as | Type | In a watch |
|---|---|---|
| SR626SW, 377 | Silver oxide, low drain | Best for an ordinary analog quartz watch |
| SR626W, 376 | Silver oxide, high drain | Works in any watch, and suits one with a backlight, alarm or chronograph |
| LR626, AG4, 177, LR66 | Alkaline, 1.5 V | Fits, but runs down sooner and the voltage sags; use only in a pinch |
| SR66 | Older or alternative codes | Same size; check the chemistry on the pack |
Look-alikes that won't fit
These are also 6.8 mm across, so they look right in the pack, but the thickness is different. They aren't substitutes.
Never use a lithium coin cell in its place. Lithium cells run at 3 volts, twice what a silver-oxide watch movement expects.
Getting a 377 changed
Watch shops in our directory list battery changes from $4.99 to $115, with a median of $15, usually done while you wait. A shop has the tools to open a screw-down caseback without marking it, and can replace the gasket and pressure-test a water-resistant watch. 455 shops in the directory list battery replacement. To do it yourself, follow how to change a watch battery.
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Questions
- Is 377 the same as 376?
- They're the same size (6.8 × 2.6 mm) and the same silver-oxide chemistry. The 377 (SR626SW) is the low-drain version for ordinary analog watches; the 376 (SR626W) is high-drain, for watches with a light, alarm or chronograph. The 376 works in any watch that takes a 377.
- Is LR626 the same as SR626SW?
- Same size, different chemistry. LR626 (also sold as AG4) is alkaline and SR626SW is silver oxide. The alkaline cell fits, but it holds about 10–18 mAh against 24–28 mAh and its voltage drops as it drains, so a watch runs a shorter time on it.
- Can I use a 364 instead of a 377?
- No. Both are 6.8 mm across, but the 364 is 2.1 mm thick and the 377 is 2.6 mm. A thinner cell won't press against the contacts, so the watch won't run reliably.
- How long does a 377 battery last?
- In a typical analog quartz watch, two to five years. It holds about 24–28 mAh; a running chronograph, a backlight or an alarm drains it faster. Unused cells keep for several years in the pack.