The SR626SW is a small silver oxide watch battery, and its most common equivalents are 377 and 376. All three are the same 1.55-volt cell, about 6.8 mm wide and 2.6 mm thick. Its international (IEC) code is SR66. Energizer lists its 377 battery as a replacement for 376/377, 377BP, D377, SB-AW, SR626SW and SR66.
This guide uses Energizer’s data sheets to show the size, voltage and capacity of the cell, explains what all the different names mean, and covers the one equivalent to be careful with: alkaline versions like AG4 and LR626.
| Detail | SR626SW / 377 / 376 |
|---|---|
| Chemistry | Silver oxide (Zn/Ag2O) |
| Nominal voltage | 1.55 V |
| Diameter | 6.6-6.8 mm (about 0.27 in) |
| Height | 2.4-2.6 mm (about 0.10 in) |
| Typical capacity | About 24-27 mAh (to 1.2 V; varies by data sheet) |
| Weight | 0.42 g |
| IEC code | SR66 |
| ANSI/NEDA code | 1176SO |
What is the equivalent of an SR626SW battery?
The 377 is the most common equivalent, and the 376 is the same size. Energizer sells a single 377/376 cell and lists its 377 as a replacement for:
- SR626SW, the common name based on the size (6.8 mm by 2.6 mm)
- SR66, the international IEC code
- 376/377, 377BP, D377 and SB-AW, other maker and retail codes
Energizer’s battery cross-reference guide lists 377, SP377, V377, 37, SR626SW, G4 and Type BA against the same 377/376 cell, for watches, digital thermometers and calculators.
What does SR626SW mean?
- S: silver oxide chemistry
- R: round
- 626: the size, roughly 6.8 mm wide (shown as “6”) and 2.6 mm thick (“26”)
- SW: a maker’s suffix. Some brands sell SW and W versions of the same size, so match the letters on your old battery if you can.
The official IEC name for the same cell is simply SR66. That is why you may see SR626SW, SR66 and 377 printed on different packs of the same battery.
Is AG4 the same as SR626SW?
It is the same size, but not always the same chemistry. AG4 is often sold as an alkaline cell, and codes that start with “L”, like LR626 or LR66, are alkaline (just as LR44 is the alkaline version of the SR44). An alkaline cell is 1.5 V instead of 1.55 V, and Energizer’s silver oxide manual says silver oxide has a flatter discharge curve than alkaline, so its voltage stays steadier as it runs down. An alkaline cell will fit, but for a watch the silver oxide SR626SW or 377 is the better match. Check the chemistry printed on the pack before you buy.
377 vs 376: what is the difference?
They are the same size and chemistry, and Energizer sells one cell labelled 377/376 with a single data sheet, so for Energizer’s cells there is no difference. If your watch maker names one number, use that one.
Where SR626SW batteries are used
Energizer sells its 377 as a watch battery and lists watches, toys, glucose monitors and calculators as typical uses; its cross-reference guide adds digital thermometers. Many small analogue watches take this size, but always check the code on the old battery or in the watch’s manual, because watch batteries come in many very similar sizes.
Button battery safety
Small button batteries are a choking and swallowing hazard for children. Keep new and used cells out of reach, and get emergency medical help straight away if you think a child has swallowed one.
Related battery guides: LR44 vs 357 vs AG13 vs SR44, CR2032 vs CR2025 vs CR2016 and AA vs AAA batteries.
Frequently asked questions
Is SR626SW the same as 377?
Yes. Energizer lists its 377 battery as a replacement for the SR626SW. Both are 1.55 V silver oxide cells of the same size.
Can I use 376 instead of 377?
Usually, yes. They are the same size and chemistry, and Energizer sells them as one cell labelled 377/376. Follow your watch maker’s advice if it names one.
What size is an SR626SW battery?
About 6.8 mm in diameter and 2.6 mm thick (6.6-6.8 mm by 2.4-2.6 mm in Energizer’s data sheet).
What voltage is an SR626SW?
1.55 volts. Alkaline versions of the same size, like AG4 or LR626, are 1.5 volts.
What is the IEC code for a 377 battery?
SR66. In the US, the ANSI/NEDA code is 1176SO.
Is AG4 a good replacement for SR626SW?
It fits, but an AG4 is often alkaline, with a slightly lower voltage that drops more as it runs down. For a watch, a silver oxide SR626SW or 377 is the better choice.
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