Best Smart Thermostats Under $100

Smart thermostats have a reputation for being expensive — and the flagship models often are. The Nest Learning Thermostat and ecobee Smart Thermostat Enhanced both sit well above $100, packing adaptive learning algorithms, remote room sensors, and air quality monitoring into premium packages.4 But if your priority is reliable app control, flexible scheduling, and real energy savings without the premium price tag, three mainstream options deliver all of that for under $100.

We looked at the Amazon Smart Thermostat, the Google Nest Thermostat, and the Sensi Smart Thermostat — the only widely available smart thermostats that consistently stay under the $100 line while still offering WiFi connectivity, scheduling, and voice assistant integration. None of them include remote room sensors or learning features at this price (those are premium features reserved for $150+ models), but each one nails the fundamentals in a slightly different way.

Here's how they compare, and which one belongs on your wall.

1. Amazon Smart Thermostat — Best Overall Value

The Amazon Smart Thermostat is the cheapest mainstream smart thermostat you can buy, landing in the $60–80 price band.1 For that money you get full Alexa integration, app-based remote control, and a feature called Alexa Hunches that can automatically adjust your thermostat based on whether it thinks you've left home or gone to bed.

Installation is designed for DIY — Amazon keeps the setup process straightforward, and the thermostat works with most 24V HVAC systems. The trade-off: there's no C-wire workaround included, so if your home doesn't have a C-wire you'll need to factor in the cost of an adapter or a different pick entirely.

Best for: Alexa households who want the lowest possible price and don't need C-wire flexibility.

2. Google Nest Thermostat — Best for Google Home Users

Google's entry-level Nest Thermostat (not to be confused with the pricier Learning Thermostat) brings the clean, mirror-faced design Nest is known for at a price that stays under $100.2 It's ENERGY STAR certified, integrates with Google Assistant for voice control, and offers simple scheduling through the Google Home app.

What you don't get at this tier is the adaptive learning that made the Nest brand famous — the Learning Thermostat's ability to build a schedule automatically by observing your habits is reserved for the $150+ model.5 The entry-level Nest requires you to set your own schedule, though the app makes that process relatively painless.

Best for: Google Home ecosystem users who want polished design and Energy Star savings without learning-thermostat pricing.

3. Sensi Smart Thermostat — Best for Tricky Wiring

The Sensi Smart Thermostat's standout feature is install flexibility: it doesn't require a C-wire for many HVAC systems, which makes it the go-to choice for older homes where running new wiring isn't practical.3 Like the Nest, it's ENERGY STAR certified, and it offers flexible scheduling through the Sensi app with remote access from anywhere.

The compromise is in software polish. The Sensi app is functional but doesn't match the refined experience of the Google Home or Alexa apps. It supports both Alexa and Google Assistant for voice control, giving it broader assistant compatibility than either of the other two picks.

Best for: Homes without a C-wire, or households that use both Alexa and Google Assistant and want compatibility with both.

How They Compare

All three offer WiFi-based app control and scheduling. None include remote room sensors at this price — that's a feature you'll find on the ecobee Smart Thermostat Enhanced and Nest Learning Thermostat, both of which sit above $100.4

The bottom line: If you want the absolute lowest price and you live in an Alexa household, the Amazon Smart Thermostat is hard to beat. If you're invested in Google Home and value design polish, the Nest Thermostat is the natural fit. And if your home's wiring is the obstacle, the Sensi Smart Thermostat removes that barrier entirely.

Disclosure: We may earn a commission when you purchase through links on this page. That doesn't influence our recommendations — we call them as we see them.

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