Angry Fitbit users are suing the smart watch company for allegedly displaying wrong and potentially harmful data.

The fitness tracker, which costs upwards of $100, displays a wearer’s heart rate, steps taken and calories burned.

But a growing number of users are claiming the data offered is often wildly inaccurate.

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One complainant told US TV show Today she had noticed her heart rate numbers were way off.

“I like to work out. I like to be fit,” Kate McLellan said.

“My Fitbit was saying that [my heart rate] was at 114, which is really, really low.”

The company indicated it would fight the allegations in a statement.

“We do not believe this case has merit,” a spokesperson said.

“Fitbit stands behind our heart-rate technology and strongly disagrees with the statements made in the complaint and plans to vigorously defend the lawsuit.”

Users also complained about their Fitbits would not tell the time unless they registered their device on the company’s website – a process which involves agreeing to terms which deem a user cannot take certain legal action against the company.

Fitbit responded to these concerns by saying users had 30 days to opt out of the non-arbitration agreement.

This isn’t the first time the fitness tracker has been sued by unhappy customers.

In 2015, a class action was filed against Fitbit claiming the device had caused skin rashes to develop on users’ wrists.

The company reacted by telling people to give the device “a rest” every now and then.