The fastest way to find your watch battery size
The easiest method is to open the watch case back and look at the battery itself—the size code is printed directly on it. If the battery is still inside, you will see a number like SR626, SR927, or LR44 stamped on the metal surface. Write down that exact code and you have everything you need to buy a replacement.
If the case back is sealed or you cannot open it without tools, check the watch manual or the original packaging—most include the battery type. If you no longer have those, the watch brand's website often lists battery sizes by model number, which you can usually find on the case back or dial.
Key Takeaways
- The battery code is printed directly on the battery itself and is the most reliable way to identify the correct size.
- Watch manuals, original boxes, and manufacturer websites all list battery sizes by model number if you cannot open the case.
- Battery codes like SR626 or LR44 tell you both the chemistry (silver oxide or alkaline) and the physical dimensions.
- Taking the watch to a jeweler or watch repair shop costs nothing and takes five minutes if you want someone else to identify it.
Opening the case back to read the battery code
Most watches have a removable case back held on by small screws or a snap fit. Use a case back opener tool (available at hardware stores for a few dollars) or a thin flathead screwdriver to gently pry the back off. Work slowly around the edge so you do not strip the grooves.
Once the back is open, you will see the battery sitting in a small metal holder. The code is stamped on top of the battery in white or black lettering. Common codes include SR626 (silver oxide, 1.55 volts), SR927 (silver oxide, 1.55 volts), LR44 (alkaline, 1.5 volts), and CR2032 (lithium, 3 volts). Write down the exact code—do not guess or round it.
If the battery is corroded or the lettering is worn away, you may need to remove it to read the code clearly. Gently lift the battery out with a plastic tool or wooden stick (metal can scratch it). Once you have the code, you can close the case back and order a replacement online or at a pharmacy.
Using the watch model number to find battery information
If you cannot open the case or the battery code is unreadable, locate the model number on the watch itself. This is usually printed on the case back, the dial, or inside the band. It looks like a string of letters and numbers—for example, "Timex T2N291" or "Citizen BM8180-03E".
Go to the manufacturer's website and search for your model number in their support or product section. Most brands list the battery type in the specifications or manual read. If the website does not have it, try searching "[brand name] [model number] battery" in a search engine—watch forums and retailer pages often have this information.
Write down the battery code exactly as it appears. Do not assume two watches from the same brand use the same battery, because they often do not.
What the battery code letters and numbers mean
Watch battery codes follow a standard format that tells you the chemistry and size. The first letters indicate the type: SR means silver oxide (most common, 1.55 volts), LR means alkaline (1.5 volts), and CR means lithium (3 volts). The numbers that follow describe the physical dimensions in millimeters.
For example, SR626 is a silver oxide battery 6.8 millimeters in diameter and 2.6 millimeters thick. SR927 is the same chemistry but 9.5 millimeters in diameter and 2.7 millimeters thick. These small differences matter—putting an SR927 in a watch designed for an SR626 will not fit, and using the wrong voltage can damage the watch's circuit.
When you order a replacement, match the code exactly. Do not buy a battery that is "similar" or "compatible"—the code exists so you get the right one.
Asking a jeweler or watch repair shop
If you do not want to open the watch yourself or cannot find the information online, take it to a jewelry store or watch repair shop. They can identify the battery size in seconds by looking at the case back or opening it for you. Most shops will tell you the size for free, even if you do not buy the battery from them.
This is also a good option if the case back is glued shut or if you are worried about damaging the watch. A professional can open it safely and may even replace the battery while you wait for a small fee.
Common battery sizes and what watches use them
| Battery Code | Chemistry | Voltage | Common Uses |
|---|---|---|---|
| SR626 | Silver oxide | 1.55V | Small dress watches, digital watches |
| SR927 | Silver oxide | 1.55V | Larger dress watches, some sports watches |
| LR44 | Alkaline | 1.5V | Cheap digital watches, some calculators |
| CR2032 | Lithium | 3V | Smartwatches, some digital watches |
| SR516 | Silver oxide | 1.55V | Very thin watches, some vintage models |
Silver oxide batteries (SR codes) last longer and are more stable than alkaline (LR codes), so they cost a bit more but are worth it for watches you wear regularly. Lithium batteries (CR codes) are used in devices that need higher voltage, like some smartwatches and digital sports watches.
Frequently Asked Questions
Can I use a different battery code if it is the same voltage?
No. Voltage is only one part of the equation—the physical size and thickness must match exactly. A battery that is too thick will not fit in the case, and one that is too thin will rattle and lose contact with the terminals. Always use the exact code printed on the old battery.
What if I lost the old battery and cannot find the model number?
Take the watch to a jeweler or repair shop and they will identify it by opening the case. You can also try searching for the brand and any visible text on the dial or case back in a search engine—watch enthusiast forums often have detailed specifications for older or less common models.
Does it matter if I buy a silver oxide or alkaline battery if they are the same size?
Yes, it matters. Silver oxide and alkaline batteries have different voltages and discharge rates. Using the wrong type can cause the watch to run fast or slow, or damage the circuit over time. Always match the chemistry code (SR, LR, or CR) as well as the numbers.
How do I know if the case back is screwed or snapped on?
Look at the edge of the case back. If you see small notches or grooves all the way around, it is screwed on and you need a case back opener tool. If the edge is smooth, it is likely a snap fit and you can gently pry it open with a flathead screwdriver. Work slowly and test gently—if it does not budge, stop and take it to a professional.
Can I order a watch battery online if I have the code?
Yes. Search for the battery code on any pharmacy, electronics retailer, or online marketplace. Prices are usually between one and five dollars per battery. Make sure the listing shows the exact code you need—do not buy based on a photo alone, because similar-looking batteries can have different codes.