Ring Window and Door Contact Sensor (2nd gen) is the top pick among smart door and window sensors under $20, rated 4.7 stars across 29,450 customer reviews.
RingWindow and Door Contact Sensor (2nd gen)
4.7(29,450)25% OFF$19.99$14.99
AqaraDoor and Window Sensor
4.4(6,095)10% OFF$17.99$16.19
SwitchBotContact Sensor
4.3(1,165)$16.99
SonoffDW2-WIFI
3.8(1,059)$12.23
HeimanWindow Door Alarm
4.0(148)$19.98
SonoffSNZB-04 ZigBee Wireless Door/Window Sensor
3.8(102)$17.99
MerossSmart Door and Window Sensor
3.0(36)18% OFF$21.99$17.99
SonoffSNZB-04P ZigBee Door/Window Sensor
3.9(12)$18.99- Price alerts
Door & Window Sensors under $20, updated as prices fall
We check the price of every Door & Window Sensor in the catalog daily, and email you the ones that drop into this range.
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Frequently asked questions
What are the best smart door and window sensors under $20?
Ring Window and Door Contact Sensor (2nd gen), Aqara Door and Window Sensor and SwitchBot Contact Sensor lead our ranking of smart door and window sensors under $20, ordered by customer rating weighted by how many reviews back it. The full list compares 8 products in this price range.
How many smart door and window sensors cost less than $20?
This page tracks 8 smart door and window sensors under $20 from 6 brands, with prices starting at $12.23.
Are these prices up to date?
Prices come from each product's Amazon listing and are re-checked continuously, so every card shows the latest price we have. A product whose price rises above $20 drops off this list on the next update.
Looking for more than $20?
See all the door & window sensors in the catalog, compared side by side on specs, price and rating.