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Comparison

Size 312 (brown) vs Size 13 (orange)

Sizes 312 and 13 are both 1.45 volt zinc-air hearing aid batteries with the same 7.9 mm diameter; the difference is height. The 312 (brown tab) is 3.6 mm tall with 160 to 180 mAh; the 13 (orange tab) is 5.4 mm with 280 to 310 mAh. Each aid is built for exactly one.

Size 312 (brown) and Size 13 (orange) drawn side by side at the same scale: Size 312 (brown) is 7.9 mm across, 3.6 mm thick; Size 13 (orange) is 7.9 mm across, 5.4 mm thickSize 312 (brown)Size 13 (orange) Size 312 ⌀ 7.9 mm 3.6 mm Size 13 ⌀ 7.9 mm 5.4 mm
Size 312 (brown) vs Size 13 (orange) at the same scale: 7.9 mm across, 3.6 mm thick against 7.9 mm across, 5.4 mm thick.
Size 312 (brown)Size 13 (orange)
ChemistryZinc-airZinc-air
Voltage1.45 V1.45 V
Diameter7.9 mm7.9 mm
Height3.6 mm5.4 mm
Capacity160-180 mAh280-310 mAh
Also sold asPR41, ZA312, 312A, DA312PR48, ZA13, 13A, DA13

The two sizes exist because hearing aid design trades battery life against device size. Slim receiver-in-canal aids, the most fitted style today, chose the thinner 312 and accept three to ten days per cell. Fuller behind-the-ear housings take the 13 and stretch six to fourteen days. The shared diameter means the battery doors look similar, but a 312 in a size-13 door leaves a 1.8 mm gap and no reliable contact, while a 13 will not let a 312 door close.

The universal color code settles any doubt at the shelf: brown always means 312, orange always means 13, across every brand and country. Match the tab color to the color printed on your aid's battery door or in its manual.

Usage tips apply equally to both: peel the tab, wait about a minute for the zinc-air chemistry to wake before closing the door, keep cells dry, and never peel tabs in advance since activation starts the clock whether or not the cell is used.

All about Size 312 (brown) All about Size 13 (orange)

Frequently asked questions

Can I use a size 13 in an aid that takes 312?
No. The 13 is 1.8 mm taller and the battery door will not close over it. The reverse fails too, with the short 312 losing contact in a 13-sized bay. The shared diameter tempts people to try; the height difference makes it pointless.
Which lasts longer, 312 or 13?
The 13, holding roughly 300 mAh against the 312's 170. In practice size-13 aids run six to fourteen days per cell versus three to ten for a 312. But the comparison is academic when replacing: your aid dictates the size, and streaming habits move the numbers more than brand choice.
Why does my 312 die faster than the box promises?
Bluetooth streaming is the usual culprit, cutting life by a third or more. Humidity extremes, high altitude, and severe-loss amplification settings also drain cells faster. If fresh branded cells still underperform, ask your audiologist to check the aid's current draw.

⚠️ Keep away from children. Swallowed button batteries, especially 20 mm lithium coins, cause severe injury within hours. If a child swallows one, call the 24/7 National Battery Ingestion Hotline (US) at 800-498-8666 or poison control at 800-222-1222 immediately. What every parent should know.