Along with a 7-inch Kindle Fire HD refresh, Amazon has unveiled a new range of Kindles in the form of the Fire HDX, which will come in 7-inch and 8.9-inch varieties.

Stronger contenders against the iPad, iPad mini and the new Nexus 7, the Kindle Fire HDX family shows a bit more power inside and out.

And at those prices, Amazon sure is promising a lot, with the new models coming preloaded with the new Fire OS 3.0 "Mojito", which includes the helpful, but slightly scary Mayday button.

"It's been just two years since we introduced the first Kindle Fire, and the team is innovating at an unbelievable speed," said Jeff Bezos, Amazon.com Founder and CEO.

"We've worked hard to pack this much hardware, innovation, and customer obsession into these prices."

HDX display ppi beats your ppi

Amazon is introducing Retina display-beating "HDX displays" in this new range, with the 7-inch variety boasting 323 ppi in its 1920 x 1200 resolution screen and the 8.9-inch tablet touting 339 ppi in its 2560 x 1600 resolution screen.

For pixel-peepers, comparatively, the iPad with Retina display sports a 1536 x 2048 resolution 9.7-inch screen with 264 ppi, while the new Nexus 7 has a 1920 x 1200 resolution screen with 323 ppi.

Amazon is claiming that its HDX display also has perfect colour accuracy (or 100% sRGB), as well as "dynamic image contrast", which adjusts pixel colours depending on the ambient lighting.

To power this screen, both HDX models sport quad-core 2.2 HGz processors with 2GB RAM and Ardeno 330 graphics for gaming.

Both models have HD front-facing cameras, but the 8.9-inch model also sports an 8MP rear-facing camera too.

The 8.9-inch models battery rates at 12 hours mixed use and 18 hours reading, according to Amazon, while the 7-inch model rates at 11 hours for mixed use and 17 hours for reading.

HDX varieties

Coming in 16GB, 32GB and 64GB, with Wi-Fi only or 4G-enabled, there are a variety of flavours to choose from.

Pricing for the 7-inch HDX will start at US$229 (about £143, AUD$244) for the 16GB Wi-Fi only option with Special Offers, while the 8.9 HDX will start at $379 (about £237, AUD$404) for the same configuration.

Pre-order for both models start today, with the 7-inch Fire HDX Wi-Fi variant due to start shipping on October 18 and the 7-inch 4G-capable variant shipping from November 14.

The 8.9-inch Wi-fi variant will begin shipping November 7, while the 4G-enable model is due to begin shipments on December 10.

  • Check out the details for Amazon's new Fire OS 3.0, which they're calling Mojito.