Video doorbell makers quote maximum motion detection distances that vary widely. According to Engadget, Ring says its standard maximum is about 30 feet, while eufy lists 15 feet for horizontal motion and 5 feet for vertical motion. Arlo's second-generation doorbell is listed at 13 feet, its Essential models at 16 feet, and TELUS says its sensor works best within 8 feet. These maximums are not guaranteed, and being visible in live view does not mean the device will trigger a motion event.
Detection depends on more than distance. Engadget notes that passive infrared (PIR) heat sensors are more sensitive to side-to-side movement, while Pixel Difference Analysis (PDA) compares frames to spot changes. Some doorbells combine video analytics with PIR. TELUS adds that its sensor requires continuous movement for seven seconds or more to trigger a clip, even at the most sensitive setting.
More range is not always better. Busy roads, moving trees, sunlight, and shadows can cause unwanted alerts, so companies offer motion zones and sensitivity adjustments. Battery-powered models like Google's Nest Doorbell consume more power when monitoring high-traffic areas. Ring recommends mounting its doorbells 48 inches off the ground. Subscriptions can add recorded video and smart alerts, but Engadget notes that paying does not make the physical detection range larger.