A waterproof fitness band with incredible battery life, an integrated heart-rate sensor and sleep tracking, it's difficult to see how Huami might improve on the £26.99 Mi Band 3, which is sold within Xiaomi's huge ecosystem of third-party products.

But improve on it Huami will, the company's Chief Financial Officer David Cui has confirmed during an earnings call transcribed by Motley Fool. "Each generation we learn something, we always do better,” Cui said.

When is the Mi Band 4 release date?

Mi Band 3 was announced in China in June 2018, and officially made its way to the UK in November. We'd expect to see a summer launch for Mi Band 4, which Cui claims won't be here in March or April but it will be announced this year.

How much will Mi Band 4 cost?

Pricing is typically kept constant with Xiaomi products, at least as much as is possible. We would be surprised if they Mi Band 4 cost anything more than £30 in the UK, and more likely it will retain the current £26.99 price.

What new features can we expect in Mi Band 4?

The original Mi Band went on sale in summer 2014, a basic sleep- and fitness tracker with standout battery life and a cheap price. In each new generation since it has improved, with Mi Band 1S adding a heart-rate sensor, Mi Band 2 adding an OLED screen with basic notifications, and Mi Band 3 increasing the size of that display and adding the ability to read messages onscreen. The most recent generation also improved waterproofing, allowed the tracking of specific activities, and swapped in a higher-capacity battery. So what's left to add in Mi Band 4? Here's our wish list.

Swim tracking

Though Huami added the ability to track certain activities in Mi Band 3, a glaring omission given its now proper waterproofing is swimming. It's often overlooked in cheap fitness trackers, but if Huami were to add the feature it would significantly add appeal.

An improved wrist band

Huami has used the same hypoallergenic wristband since gen 1 for Mi Band. It's simple and it does the job, but over time it becomes loose and there's nothing to stop the tracking module itself from falling out the band and being misplaced. We'd like to see some improvements here.

Wireless charging

Xiaomi is beginning to include support for wireless charging in some of its phones (Mi Mix 2S, Mi Mix 3 and Mi 9), and Mi Band would benefit greatly from the addition. The current band uses a proprietary charger, which requires you to first remove it from the wrist band and then plug it in via a USB port.

Colour display

In the past two revisions Huami has first added a display and then improved it, but it could be better still with a splash of colour.

ECG sensor

It's possible we'll never see this feature in Mi Band given its low price, but electrocardiagram is a more accurate type of heart-rate sensor than the optical scanner found in Mi Band 3 and other fitness trackers. That means it can also provide better insights into your health.

Improved Mi Fit app

An obvious difference between Mi Band and rivals such as Fitbit is the quality of the mobile companion app. We'd like to see more competitive and social features, and the ability to earn motivational badges.

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