Home lock calculator
Smart Lock Annual Battery Cost Calculator
Estimate annual battery spending for one or more smart locks.
Result
Annual battery cost (USD)
—
Cost per lock per year (USD)
—
Rechargeable est. saving (USD)
—
—
Formula
Calculation logicPrices are user-provided estimates, not live market data.
Smart-Lock Power, Signal, and Battery Life
Signal decides the protocol
Estimate 2.4 GHz RSSI from router distance plus 9 dB per wall. Above -65 dBm suits direct Wi-Fi; -65 to -75 is marginal; below -75, use a hub or move the access point. More than 6 Wi-Fi locks per access point needs a dedicated SSID.
Battery math
Wi-Fi drains fastest, Z-Wave/Thread slowest. Freezing weather cuts alkaline capacity first; lithium holds up. Treat the low end of the interval as the shopping trigger and keep one spare set per lock.
Verify before you buy
- Count full sets replaced per year
- Compare rechargeable payback in months
- Keep one spare set per lock