Both batteries measure roughly 7.9 mm in diameter, yet their heights and capacities differ enough to make them incompatible in most devices.9 mm and look nearly identical on a pharmacy shelf. The two sizes differ in thickness by roughly 1.8 mm, which is enough to keep a size 312 from seating properly in a hearing aid built for a size 13.
Pick the wrong cell and the battery door will not close, the contacts will not meet, and the device will stay silent until you swap in the correct one.
This guide covers the real differences between size 13 and 312 hearing aid batteries, dimensions, color tabs, which devices use each, and what happens if you mix them up.
The Short Answer, and Why Getting It Right Matters
Size 13 and size 312 are distinct button cell batteries, despite their nearly identical appearance. Both share the same diameter of about 7.9 mm, which is the root of the confusion at the shelf, but size 13 stands roughly 5.4 mm tall while size 312 measures about 3.6 mm tall.
That extra thickness on the size 13 holds roughly 310 mAh of capacity versus about 180 mAh in the slimmer size 312, which is why one runs noticeably longer than the other in real-world use. Picking the wrong cell is not a minor inconvenience either. A size 312 dropped into a size 13 compartment sits loose and fails to make an electrical connection.
A size 13 forced into a size 312 door will not close and may crush the battery or warp the contacts. Either way, the hearing aid stays dead until you fit the correct replacement, and that downtime is the real cost of guessing between the two.
The confusion takes about 30 seconds to clear up. A quick check of the color tab on the packaging, the number stamped on the flat side of an old battery, or the manual that came with the device removes all doubt before you spend a cent. Orange means size 13. Brown means size 312. Either clue alone is usually enough.
How the Two Sizes Differ in Dimensions and Capacity
The numbers tell the whole story. Both batteries share a diameter of roughly 7.9 mm, which is why the two cells look interchangeable at a glance, but height is where they diverge. Size 13 measures about 5.4 mm tall while size 312 measures about 3.6 mm tall, and that 1.8 mm gap decides everything downstream.
The wider, shorter cell fits where the slimmer one does not, and each hearing aid battery compartment is machined to accept only one specific height. The extra height in size 13 carries more active zinc anode material inside the can, which translates to roughly 310 mAh of capacity versus about 180 mAh for size 312.
Higher capacity means noticeably longer runtime between battery changes for size 13, often a full extra day or two in a power-hungry BTE model. Voltage and zinc-air chemistry are identical between the two, so size alone explains every performance gap you will see on a run-time chart.
Side-by-side spec comparison
| Specification | Size 13 (PR48) | Size 312 (PR41) |
|---|---|---|
| Diameter | 7.9 mm | 7.9 mm |
| Height | 5.4 mm | 3.6 mm |
| Capacity | ~310 mAh | ~180 mAh |
| Voltage | 1.45 V | 1.45 V |
| Color tab | Orange | Brown |
| IEC code | PR48 | PR41 |
| Typical use | Larger ITE and BTE models | Mini BTE and RITE devices |
That table is the fastest reference you can carry with you. Screenshot it or memorize the color-tab rule, and the rest of the shopping trip becomes a non-event.
The Color Tab System That Solves Shelf Confusion
The hearing aid industry adopted a universal color code decades ago, and it remains the fastest way to tell the two sizes apart. Size 13 is marked with an orange tab and size 312 is marked with a brown tab by convention, and that color shows up on three places at once: the cardboard package, the foil sticker on the back of each battery, and most manufacturer inserts inside the box.
Walk up to any shelf of Rayovac, Duracell, Energizer, or Power One cells and the colors line up across every one of them. Behind the color sits a second layer of certainty in the form of IEC codes, with PR48 designating size 13 and PR41 designating size 312 under the IEC 60086 standard used across North America and Europe.
ANSI uses the same numeric naming you see printed on the can, so learning both the color and the code future-proofs you against unfamiliar store brands or imported packaging where the wording might shift but the colors and codes stay fixed.
For shoppers ordering online, the printed number on the battery itself is the most reliable check. The digits 13 or 312 are stamped directly into the flat face of every cell, usually right next to the brand logo. If the printed number matches the slot you are filling, you have the right battery regardless of how the listing photo looks.
Once the color rule is second nature, the next question is which hearing aid brands actually ship with each size.
Pro tip: Pull a used battery out of the hearing aid before you order replacements. Match that exact number and color tab against the new pack, and a wrong shipment becomes nearly impossible.
Which Hearing Aids Use Size 13 and Which Use Size 312
The two battery sizes tend to land in different categories of hearing aids, which is one reason the confusion persists across age groups. Size 13 typically powers larger in-the-ear (ITE) and behind-the-ear (BTE) models that have room for a thicker cell.
Size 312 dominates modern mini behind-the-ear and receiver-in-canal (RITE) devices where slim profiles matter. If the hearing aid is small enough to nearly disappear behind the ear, it almost always runs on 312.
Confirming which one your device takes
The manufacturer’s manual is the fastest way to confirm the right battery, and most audiologist offices print the size on the fitting paperwork handed out at delivery. The battery door itself acts as a final check, since each compartment is machined to accept only one specific height and a wrong-size cell simply will not sit flush.
When in doubt, a quick call to your audiologist’s office removes any remaining ambiguity before you commit to a pack, and most will happily confirm the size over the phone from your file.
What Happens If You Try to Force the Wrong Battery
Forcing a mismatch is tempting when a pharmacy is closing and the only pack on hand looks close enough. Resist it. A size 312 dropped into a size 13 compartment sits loose because it is about 1.8 mm too short, which means the negative terminal never reaches the contact spring and the hearing aid stays silent.
You might assume the battery is dead and toss a perfectly good cell, when the actual problem is the height mismatch. A size 13 forced into a size 312 door is where real harm can show up. The taller cell will not close properly and may crush the battery or warp the delicate contact springs inside the compartment.
Forcing either direction risks scratching those springs, which can permanently disable that battery slot and send the hearing aid in for service. Neither scenario is dangerous in a safety sense, but both leave you without functioning amplification until the device is repaired.
Returning the unused battery promptly keeps the cost of the mistake close to zero. Most pharmacies and online retailers accept unopened packs, so a wrong purchase rarely turns into lost money when you catch it within the return window.
A Three-Step Way to Pick the Correct Battery Every Time
Confirming the right battery does not require guesswork or brand loyalty. A simple three-step check works at any store, on any screen, for any hearing aid you own.
- Pull the old battery. Read the number stamped on the flat side. If it says 13, you need size 13. If it says 312, you need size 312.
- Match the color tab. Cross-check the new package against orange (size 13) or brown (size 312). The tab color appears on the box, the foil sticker, and the individual cell.
- Confirm against the manual. When the first two steps leave any doubt, glance at the hearing aid manual or your audiologist’s fitting notes for the listed battery size.
Buying in sealed packs of six keeps a spare on hand so the next replacement takes seconds instead of a pharmacy run. Storing batteries at room temperature with the tab still sealed preserves their full multi-year shelf life, since zinc air cells lose charge faster once the tab is pulled and oxygen starts flowing through the air holes on top.
Rechargeable alternatives have grown popular in recent years, but disposable zinc air cells remain the default for most prescription hearing aids. Sticking with the size printed on your device keeps the swap simple and avoids the contact damage that comes from improvising with the wrong cell.
The Bottom Line
Size 13 and size 312 hearing aid batteries share a diameter but differ in thickness, capacity, and the hearing aids they fit. Orange tab means 13, brown tab means 312, and the number stamped on an old battery settles every other question before you commit to a pack.
Match the cell to your device on the first try and your hearing aid stays powered without a wasted trip back to the pharmacy.
FAQ
Are size 13 and 312 hearing aid batteries the same size?
No. They share the same diameter of about 7.9 mm but differ in height. Size 13 measures roughly 5.4 mm tall and size 312 measures about 3.6 mm tall, so the two cannot be swapped in the same hearing aid.
What is the difference between size 13 and size 312 hearing aid batteries?
Size 13 is thicker and holds roughly 310 mAh of capacity, while size 312 is slimmer with about 180 mAh. Size 13 uses an orange color tab and the IEC code PR48, while size 312 uses a brown tab and the IEC code PR41.
Can I use a size 13 battery in a hearing aid that takes 312?
No. A size 13 cell will not seat properly in a size 312 compartment and may crush the battery or warp the contact springs. Use the size your hearing aid was built for.
Which hearing aids use size 13 vs size 312 batteries?
Size 13 typically powers larger in-the-ear and behind-the-ear models with room for a thicker cell. Size 312 is the most common choice for mini behind-the-ear and receiver-in-canal devices where a slim profile matters.
Are 312 batteries smaller than 13 batteries?
Yes. Size 312 is about 1.8 mm shorter than size 13, even though both share the same diameter. The shorter height is what gives size 312 its slimmer runtime and its place in smaller hearing aids.
How do I tell the difference between 13 and 312 hearing aid batteries?
Look at the color tab on the package or the sticker on the battery. Orange means size 13 and brown means size 312. The number stamped on the flat side of the battery gives a second confirmation.
