Smart Plugs vs. Smart Thermostats: Where Should You Start?

If you're just starting to make your home smarter to save energy, two devices come up first: smart plugs and smart thermostats. They solve different problems, cost very different amounts, and one delivers far more savings than the other. Here's how to decide where to begin.

The Short Version#

If your goal is cutting your energy bill, start with a smart thermostat — heating and cooling is where the real money is. Smart plugs are cheaper and useful, but they target a much smaller slice of your energy use. If your goal is convenience or dipping a toe in for $15, a smart plug is a low-risk first step.

Why the Thermostat Wins on Savings#

Heating and cooling account for roughly half of a typical home's energy use — by far the largest single category. A smart thermostat targets that directly by automating temperature setbacks when you're asleep or away, using geofencing or occupancy sensing so you don't have to remember to adjust anything.

Independent testing (rather than manufacturer marketing) generally shows savings in the single digits to low-teens percent on heating and cooling for typical households — what the data actually shows — with bigger gains in more extreme climates and for households that previously did no scheduling at all. At $130–$250 for most mainstream models, plus utility rebates that are common in many states, the payback is usually reasonable.

What Smart Plugs Actually Do#

A smart plug sits between a wall outlet and a device, letting you control power remotely or on a schedule. For energy savings, their main value is tackling "phantom" or standby power — the electricity devices draw even when off or idle (TVs, game consoles, chargers, entertainment centers).

The honest caveat: for most households, phantom load is a relatively small share of the total bill. Cutting it is real, but it's measured in dollars per month, not the larger sums a thermostat can save on HVAC. Smart plugs shine more for convenience and automation (lamps on a schedule, "off" routines) than for dramatic bill reduction.

You don't have to guess at your own share. Splitting a year of bills into heating, cooling and always-on baseload shows how big your standby load actually is — and if you want it broken down device by device, that's the job a whole-home energy monitor does.

Cost and Effort Compared#

A Sensible Starting Order#

1. If you can install a thermostat easily (you have a C-wire or a compatible system): start there — it targets your biggest energy expense. Compare the three main brands before you buy.
2. If you want the cheapest possible first step: grab a smart plug or two for your worst phantom-load offenders, then move to a thermostat once you're comfortable.
3. Either way, check whether your utility offers rebates before buying — many discount smart thermostats, and some run demand-response programs that pay you small annual credits for participating.

Both devices are legitimate upgrades. The difference is scale: the thermostat plays where the big energy money is, while smart plugs are a low-cost, high-convenience entry point. Start based on which goal — maximum savings or minimum friction — matters more to you.

Worth keeping in proportion, though: a thermostat optimizes usage within the efficiency your house already has. If the house leaks heat, insulation and air sealing move the ceiling that both of these devices are working under.