| Code (listed equivalents) | Chemistry | Diameter × height (mm) | Voltage | Planning use |
|---|---|---|---|---|
| CR2032 (ECR2032, DL2032) | Lithium | 20.00 × 3.20 | 3 V | Fit only where the watch calls for lithium; never use it in place of a 1.5 V cell. |
| CR2025 (ECR2025, DL2025) | Lithium | 20.00 × 2.50 | 3 V | Same diameter as CR2032 but lower, so check the compartment depth before treating them as the same part. |
| SR626SW | Silver oxide | 6.80 × 2.60 | 1.55 V listed | Search equivalents under SR626SW as well, because shops use either code. |
| SR716SW (315, SR67) | Silver oxide | 7.9 × 1.6 | 1.55 V listed | A slim silver oxide cell; look for 315 when the SR code is not stocked. |
| 303 (SR44, SR1154SW) | Silver oxide | 11.60 × 5.40 | 1.55 V listed | The silver oxide choice in this size; SR44 is the same cell. |
| LR44 (A76, V13GA, KA) | Alkaline | 11.60 × 5.40 | 1.5 V | Physically matches 303/SR44, so size alone will not tell you which one belongs in the watch. |
Sizes, chemistries and equivalent codes come from the watch battery cross-reference table and the watch and coin cell sizing chart, whose 303 entry (11.6 x 5.4 mm) confirms the millimetre units.
A watch battery size chart lets you decode a button cell: the prefix letters give the chemistry, the listed diameter and height give the fit, and voltage rules out lithium substitutes for 1.5 V cells.
If the watch itself is still undecided, how to choose a watch is the broader decision. This guide handles the cell inside once you own one.
What a wrong match costs you
The costly mistake with a button cell is matching the size and ignoring the chemistry. The cross-reference table notes that lithium watch batteries are 3 volts, not 1.5 volts, and that they cannot be substituted for a 1.5 volt silver oxide or alkaline cell (watchbattery.co.uk). A lithium cell that drops neatly into a well built for a 1.5 V cell is still the wrong part.
That changes how you shop. Use these rules when the shelf offers something close but not identical:
- Treat the prefix as a gate. A CR cell is lithium and 3 V. An SR or LR cell sits in the 1.5 V class. Cross that line only if the watch maker specifies it, never because the dimensions agree.
- Stay inside the chemistry first, then the size. Look for a same-chemistry equivalent code before considering any other family. Listings often carry several codes for one cell, so a different number does not mean a different battery.
- Stop when the old cell cannot be read. If you cannot confirm the chemistry from the printed code or the watch’s documentation, a repairer can identify it. Guessing is how a 3 V cell ends up in a 1.5 V movement.
The next section shows how the letters and numbers work, so you can check a match yourself.
Decoding the battery code
A battery code is a short label for a chemistry and a size, and the table pairs them consistently. In the cross-reference table the CR2032 row is lithium, the SR626SW row is silver oxide and the LR44 row is alkaline (watchbattery.co.uk). Watch cells are button cells, so the same decoding applies to anything flat and round in the chart.
Prefix letters
- CR means lithium. CR2032 is listed at 3 V, 20.00 diameter and 3.20 height, with ECR2032 and DL2032 as equivalent codes.
- SR means silver oxide. SR626SW is listed in the cross-reference table with its diameter and height. The sizing chart puts silver oxide codes at 1.55 V, for example the SR716SW at 7.9 x 1.6 mm (lawrencesamble.co.uk).
- LR means alkaline. LR44 is listed at 11.60 by 5.40.
Equivalent codes
The same cell is sold under many names. The row for SR626SW carries several equivalent codes, so a shop that lists a different code for it still stocks your cell. The sizing chart is laid out the same way, with columns for code, equivalent codes, size and voltage. Read across a row rather than hunting for an exact string match.
Once you know the chemistry, the remaining question is usually whether a cell from a neighbouring family will do.
Choosing between LR and SR
The tables show that an LR cell and an SR cell can be the same physical size. LR44 is listed as alkaline, and code 303, with SR44 as an equivalent, is listed as silver oxide with the same dimensions (watchbattery.co.uk). The sizing chart agrees on 11.6 x 5.4 mm and lists silver oxide at 1.55 V.
So you can ask whether LR can stand in for SR, and the answer is that it fits physically but size does not settle it. Both are 1.5 V-class cells, which is why the swap is not ruled out the way a lithium swap is. The deciding factor is what the watch calls for.
- If the old cell or manual says SR, buy SR. Silver oxide is the stated chemistry, so keep it.
- If the watch was running an LR cell, an LR replacement is the like-for-like choice. Do not move to lithium to get a different performance.
- If only the other family is in stock, wait or ask. A repairer can say whether the movement accepts it. Do not improvise with a code you cannot match to a row in the chart.
Cross-referencing a worn or unfamiliar code
When the print on the old cell has rubbed off, measure it. The cross-reference table can be sorted by diameter or by height, so a measured cell leads you to candidate rows without a known code (watchbattery.co.uk). Measure both dimensions, because two lithium rows can share a diameter and differ only in height.
A measurement narrows the size, not the chemistry. After sorting, read the chemistry column for each candidate and compare it with what the watch needs. If two rows share a size, as 303 and LR44 do, the chemistry column is what separates them. The 303 and LR44 pair is the clearest case where measuring alone would leave you with two possible cells.
Replacing the cell
Open the case back only when you have the right cell in hand and a clean surface to work on. If water resistance matters to you, a watch repairer is the safer place to open it.
- Open the case back with a tool made for the style of back on your watch.
- Read and note the code on the old cell, and photograph it before removal.
- Match that code to a row in the chart, then confirm the chemistry before the size.
- Remove the old cell and note which side faces up.
- Fit the new cell the same way round and close the case back.
If the watch is the real question rather than its cell, What Watch Size Should You Wear? The Practical Guide To Case Diameter, Thickness, And Fit (2026) – Getoku covers case diameter, thickness and fit. Keep the note of your code somewhere you will find it, for instance with other small items you carry, a topic The Ultimate Guide To Different Types Of Bags: Find The Perfect One For Every Occasion – Getoku takes up.
Frequently asked questions
Is a CR2025 a drop-in replacement for a CR2032?
No. Both are lithium cells with the same listed 20.00 diameter, but the CR2025 is listed at 2.50 height against 3.20 for the CR2032 (watchbattery.co.uk). Fit the code the watch specifies, and check the compartment depth before trying the other.
Why can a GR927 not be swapped for a CR927?
The table’s note on the National GR927 says its replacement is the 399 silver oxide cell, not the CR927 3 V lithium cell (watchbattery.co.uk). Similar-looking codes can belong to different chemistries, so read the row, not just the digits.
What replaces an old mercury cell?
Mercury cells are no longer made, so the only alternative is a silver oxide cell of the same size. That raises the voltage slightly, so check that the device will not be affected by the increase (watchbattery.co.uk).