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Doorbell transformer voltage and VA, in plain words

Updated September 19, 2026

A doorbell transformer steps household power down to a low voltage for the button and chime. Blink's support page puts that at about 10 to 24 volts. A video doorbell needs enough volts and enough VA from it. The floor on the 7 picks here is 8, 10 or 16 VAC, and every one tops out at 24.

Volts and VA

Volts is the pressure. VA, short for volt-amps, is how much power the transformer can hand over. A plain button needs almost none. A camera with WiFi and night vision needs more, all day. That is why makers give both numbers. Blink says an 8 VAC, 10 VA transformer is the smallest it recommends, and that below that its app shows "Wired power not supported" and the wall chime will not sound.

Which floor each pick has

Google's compatibility page gives the Nest Doorbell (wired, 3rd gen) 16 to 24 V AC and 10 to 40 VA in North America, and says some homes need a transformer upgrade to meet it. Arlo's page asks for 8 to 24 VAC and at least 10 VA for this Arlo model.

When a maker's own pages disagree

eufy's E340 spec page says existing wiring at 16 to 24 V and 10 VA. A general eufy support answer about its wired doorbells says 16 to 24 VAC and 30 VA or above. Those are different products, and the pages do not explain the gap. If you plan to wire an E340 and your label shows less than 30 VA, ask eufy first, or run it on the battery.

How to find your transformer

1. Look near the main electrical panel, inside the chime box, and in the garage or attic. Those are the spots Blink's page lists.
2. Read the label. You want something like "16V 10VA". Some labels say "max load" instead of VA.
3. Arlo's page says a multimeter gives the most accurate reading. If you are not used to one, skip it and call an electrician.

If your transformer is too small

You have three choices. Pick a doorbell with a lower floor. Pick a battery model and cap the wires. Or have a licensed electrician fit a larger transformer. Ring's listing also warns against halogen or garden-lighting transformers.

Safety: the transformer is fed by household mains voltage. Turn off the breaker before you touch doorbell wires, and leave replacing or adding a transformer to a licensed electrician. Ring's install pages add that local codes may require a permit or a professional.

Run your own door through the wiring checker, or compare all seven picks on the roundup page.