Calorie miscount Fitness devices are the oft-bullied members of the wearable world: They can't seem to get their numbers straight. And now a new study from Stanford University School of Medicine says that fitness trackers are almost universally reading how many calories you've burned incorrectly.

Of the seven devices followed by researchers at Stanford, including Apple Watch, Samsung Gear 2, Basis Peak, Fitbit Surge, Microsoft Bank, Mio Alpha2 and PulseOn, the best performing tracker in terms of calorie expenditures was off by an average of 27 percent—the worst gave readings that were 93 percent wrong. Consumers rely on their trackers for information from how much time they've spend exercising, the distance they've walked or run, and also calories burned. For those trying to maintain or lose weight, this information can be key.

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But as Stanford says, fitness devices aren't medical devices. And consumers should use them cautiously when depending on them for certain data. One area where the wearables did shine? In measuring heart rate—here the devices worked pretty accurately. Medical researchers are investing heavily on whether wearables can help wearers keep track of their heart rates, with the Apple Watch and the Cardiogram app getting high marks on their ability to detect heart irregularities including arrhythmia.

Ikea smart lightsIkea's smart home product line is going to work with Amazon Alexa, Apple HomeKit and Google Assistant, says the company. Those who buy Ikea's line of smart lights will be able to run them with voice commands through Alexa, Google Assistant and by using Apple's Home app and then Siri. The feature is expected to go live this summer or early fall.

We want a Spark DJI dropped details about its newest—and smallest—drone, the Spark at an event at Grand Central Station in New York today. The tin can-sized drone has the potential to change everything we think of in terms of selfies with its ability to shoot short video streams that mirror movie angles. More here, including how to pre-order the $499 device.