utility · 3W typical
Running a doorbell transformer costs about $0.36/month.
That's the typical doorbell transformer at 3W, run 24 hours a day at the US-average rate of 16.5¢/kWh. Change any of those and the number moves — use the calculator below to see yours.
Estimated cost
Full-power draw for 24 hours at 16.5¢/kWh.
How you use it
Cost shifts with how long it's on.
The same doorbell transformer can cost very different amounts depending on usage patterns. Three common scenarios, at the US-average rate.
always-on
$0.36
per month
continuous powered
Where you live
$0.65 spread between the cheapest and priciest states.
Same appliance, same hours of use, different zip code — the monthly cost varies this much.
| State | Rate | Monthly | Yearly |
|---|---|---|---|
| Hawaii | 41.2¢ | $0.89 | $10.83 |
| California | 31.4¢ | $0.68 | $8.25 |
| Massachusetts | 30.8¢ | $0.67 | $8.09 |
| Connecticut | 28.7¢ | $0.62 | $7.54 |
| Rhode Island | 27.9¢ | $0.60 | $7.33 |
| New Hampshire | 24.6¢ | $0.53 | $6.46 |
| Alaska | 24.3¢ | $0.52 | $6.39 |
| New York | 22.3¢ | $0.48 | $5.86 |
| Maine | 22.1¢ | $0.48 | $5.81 |
| Vermont | 21.5¢ | $0.46 | $5.65 |
| Michigan | 19.3¢ | $0.42 | $5.07 |
| New Jersey | 19.1¢ | $0.41 | $5.02 |
| Maryland | 18.4¢ | $0.40 | $4.84 |
| Pennsylvania | 18.1¢ | $0.39 | $4.76 |
| District of Columbia | 17.8¢ | $0.38 | $4.68 |
| Wisconsin | 17.4¢ | $0.38 | $4.57 |
| Delaware | 17.2¢ | $0.37 | $4.52 |
| Illinois | 16.9¢ | $0.37 | $4.44 |
| Ohio | 16.6¢ | $0.36 | $4.36 |
| Nevada | 16.3¢ | $0.35 | $4.28 |
| Indiana | 15.8¢ | $0.34 | $4.15 |
| Virginia | 15.7¢ | $0.34 | $4.13 |
| Minnesota | 15.6¢ | $0.34 | $4.10 |
| Colorado | 15.4¢ | $0.33 | $4.05 |
| Alabama | 15.2¢ | $0.33 | $3.99 |
| West Virginia | 15.2¢ | $0.33 | $3.99 |
| Florida | 15.1¢ | $0.33 | $3.97 |
| New Mexico | 14.8¢ | $0.32 | $3.89 |
| Texas | 14.8¢ | $0.32 | $3.89 |
| Arizona | 14.7¢ | $0.32 | $3.86 |
| South Carolina | 14.7¢ | $0.32 | $3.86 |
| Kansas | 14.6¢ | $0.32 | $3.84 |
| Georgia | 14.2¢ | $0.31 | $3.73 |
| Iowa | 14.1¢ | $0.30 | $3.71 |
| North Carolina | 13.9¢ | $0.30 | $3.65 |
| Missouri | 13.6¢ | $0.29 | $3.57 |
| Oregon | 13.4¢ | $0.29 | $3.52 |
| Tennessee | 13.3¢ | $0.29 | $3.50 |
| Kentucky | 13.2¢ | $0.29 | $3.47 |
| Mississippi | 13.1¢ | $0.28 | $3.44 |
| Oklahoma | 13.1¢ | $0.28 | $3.44 |
| South Dakota | 12.7¢ | $0.27 | $3.34 |
| Montana | 12.4¢ | $0.27 | $3.26 |
| Nebraska | 12.2¢ | $0.26 | $3.21 |
| Arkansas | 12.1¢ | $0.26 | $3.18 |
| Washington | 12.1¢ | $0.26 | $3.18 |
| Louisiana | 11.9¢ | $0.26 | $3.13 |
| Wyoming | 11.6¢ | $0.25 | $3.05 |
| North Dakota | 11.5¢ | $0.25 | $3.02 |
| Utah | 11.4¢ | $0.25 | $3.00 |
| Idaho | 11.3¢ | $0.24 | $2.97 |
Efficient vs. inefficient
A $10.12/year difference across the wattage range.
Swapping a high-draw model for an efficient one pays for itself. Here's what that looks like annually at typical usage.
Most efficient
1W
$0.12 per month
$1.45 per year
Typical
3W
$0.36 per month
$4.34 per year
High draw
8W
$0.95 per month
$11.56 per year
When it hits hardest
year-round peak
24/7 always-on.
Ways to cut the cost
- 1
Replace pre-2000 transformers — old cores leak 3-5W continuously
Saves 25-45 kWh/year
- 2
Upgrade to 16V 30VA for video doorbell compatibility
Right-sized transformer runs more efficiently
- 3
Remove transformer entirely if using battery video doorbell
Eliminates small but constant load
Real-world wattages
Pulled from actual spec sheets.
| Brand | Model | Watts |
|---|---|---|
| Honeywell | RCT7 16V 10VA | 2W |
| GE | 18003 Chime Transformer | 3W |
| Heath Zenith | HT-4000-A Transformer | 3W |
Picks that actually move the needle
Three products worth comparing if you're thinking about upgrading or supplementing what you have.
Some links below are affiliate links. If you buy, we may earn a small commission — it never changes the price you pay, and we only recommend picks we would stand behind.
See also
Related appliances
Sources: www.energy.gov · www.energystar.gov
Last updated: 2026-04-13