Why Battery Size Matters
Every quartz watch runs on a small coin-shaped battery. The wrong size will not fit the battery compartment, and even if it does, it may deliver the wrong voltage and damage the movement. Getting the right battery is not difficult - you just need to know how to read the code.
At Iglisi Watch we replace watch batteries every day. We stock the most common sizes and can identify the correct one for almost any watch in seconds. If you bring your watch in, we will replace it in under two minutes. But if you want to understand the system, or you need to buy a battery yourself, this guide has everything you need.
How to Read a Watch Battery Code
The code on a watch battery follows the IEC 60086 standard. The format looks intimidating, but the parts are logical:
- First letters (SR / CR / LR) - the battery chemistry. SR = silver oxide, CR = lithium, LR = alkaline.
- The number - encodes the size. The first one or two digits are the diameter in tenths of a millimetre; the last two are the height. So SR626 = 6.8mm diameter, 2.6mm height.
- Last letters (SW / W) - drain rate. SW (slow drain/watch) is optimised for the tiny, steady current a quartz movement draws. W is the same cell without the specialised separator.
Most batteries also have a numeric equivalent code (the ANSI or "button cell number"). SR626SW = 377. SR920SW = 371. These codes are interchangeable - the same cell, different naming system.
Silver oxide vs lithium: Silver oxide (SR) batteries deliver very stable voltage right until the end of their life, which is ideal for quartz movements. Lithium (CR) batteries hold more energy and work better at low temperatures - they are used in watches with alarms, backlights, GPS or solar-backup. Never substitute one chemistry for the other without checking the manufacturer specification.
The Most Common Watch Battery Sizes
These are the batteries we replace most often at Iglisi Watch, covering the large majority of quartz watches on the market:
| IEC Code | ANSI / Common # | Diameter | Height | Typical use |
|---|---|---|---|---|
| SR626SW | 377 | 6.8 mm | 2.6 mm | Casio MTP, Citizen dress, many fashion watches |
| SR621SW | 364 | 6.8 mm | 2.1 mm | Swatch, Tissot, slim quartz watches |
| SR920SW | 371 | 9.5 mm | 2.1 mm | Seiko 5 quartz, mid-size dress watches |
| SR927SW | 395 / 399 | 9.5 mm | 2.7 mm | Casio G-Shock base, sport watches |
| SR1130SW | 391 | 11.6 mm | 3.0 mm | Larger dress watches, some Seiko / Orient |
| SR44SW | 357 | 11.6 mm | 5.4 mm | Watches with backlights, dive watches |
| CR2032 | 2032 | 20.0 mm | 3.2 mm | Smart watches, GPS, large digital watches |
| CR2016 | 2016 | 20.0 mm | 1.6 mm | Thin digital watches, Casio digital slim |
| CR1616 | 1616 | 16.0 mm | 1.6 mm | Small digital watches, key fobs |
Common Batteries by Brand
Different brands tend to favour particular battery families. This is a general reference - always verify against your specific model number:
| Brand / Model Family | Typical Battery | Notes |
|---|---|---|
| Casio MTP-VD01 | SR626SW (377) | We stock this model; battery in 2 min |
| Casio G-Shock (basic) | CR2032 | Lithium - longer life with alarms/backlight |
| Casio F-91W / A168 | CR2016 | Slim lithium, 7-year rated life |
| Citizen Quartz Gold | SR626SW (377) | We stock this model; battery in 2 min |
| Citizen Eco-Drive | No battery (solar) | Uses rechargeable cell, not standard battery |
| Seiko 5 (quartz) | SR920SW (371) | Many Seiko 5 automatics need no battery at all |
| Swatch Irony / Skin | SR621SW (364) | Slim profile = thin cell |
| Tissot T-Classic | SR626SW (377) | Most common Tissot dress battery |
| Rolex Oyster Quartz | SR927SW (395) | Rare model; must use original cell |
Do not use an alkaline button cell (LR) in a watch. Alkaline batteries have unstable voltage that drops as the cell drains, causing the watch to run slower and slower rather than suddenly stopping. Alkaline cells also leak more readily. Always use silver oxide (SR) for standard quartz watches unless the manual specifies lithium (CR).
How to Find Your Watch’s Battery Size
There are four reliable methods:
- Look at the old battery. Open the caseback and read the code printed on the flat side of the old battery. This is the most accurate method because it is the exact cell the manufacturer fitted.
- Check the owner’s manual. Every quartz watch manual lists the battery reference. If you no longer have the paper manual, most manufacturers publish PDFs online - search your model number + "instruction manual."
- Look up your model number. The model number is usually engraved on the caseback (e.g. MTP-VD01D-1A for the Casio we stock). Type it into the manufacturer’s website or a watch database and the battery size will be listed in the specifications.
- Bring it in. At Iglisi Watch we identify the correct battery from the model in seconds and replace it immediately. No appointment needed - walk in during opening hours.
Workshop tip: If you are replacing the battery yourself, make a note of the code on the old cell before you buy the replacement. Photograph it with your phone. This takes five seconds and removes all guesswork at the shop.
How Long Do Watch Batteries Last?
Battery life depends on the watch’s features and the size of the cell:
- Basic quartz (time and date only): 3–5 years with a standard SR cell
- Chronograph / stopwatch function: 1–2 years if used regularly
- Backlight, alarm, or dual time: 2–3 years, depending on usage
- Casio F-91W (CR2016 lithium): rated 7 years by Casio
- G-Shock with Tough Solar: effectively unlimited with normal light exposure
The watch will usually show signs before it completely stops: running a few seconds slow per day, losing time noticeably over a week, or a “low battery indicator” hand sweep if the watch has that feature. Replace the battery as soon as you notice these signs - a depleted battery left in the case can leak and corrode the movement.
Can I Replace a Watch Battery Myself?
It is possible on many watches, but there are real risks if you do not have the right tools. The caseback requires a proper opener - using coins or knives can scratch the case or leave marks on the caseback seal. The battery must be handled without touching the cell face (skin oils affect performance). The seal must be correctly reseated to maintain water resistance. For dive watches or any watch rated above 30 metres, we strongly recommend professional replacement, as the gasket must be tested after reassembly.
At Iglisi Watch we replace batteries in under two minutes using proper tools. The cost is minimal and the result is correct. If you value your watch’s water resistance, bring it in.
Battery Replaced in Under 2 Minutes
Bring your watch to our Durrës workshop. We identify the correct battery, replace it with professional tools, and test the watch - all while you wait. No appointment needed.
Rruga Aleksander Goga · Durrës 2001 · Albania · +355 67 636 0510
Published by Iglisi Watch · Durrës, Albania · May 2026.