Amazon's best-selling item, the Kindle, combines the enjoyment of reading with the convenience of a portable and lightweight e-reader. The ultra-thin device holds up to 3,500 books and offers such enhanced options as a dictionary and note feature. Three models of the Kindle are available — the Kindle Wi-Fi, Kindle 3G + Wi-Fi and the Kindle DX. Although they share many features, they differ in a few key areas.
The Kindle Wi-Fi and 3G W-Fi both offer the option of a lower price in exchange for receiving what Amazon calls “Special Offers.” This basically means that in order to save some money, you agree to receive ads and other special offers in the form of sponsored screen savers. These ads range from gift card offers to special deals for additional Amazon purchases.
Both the Wi-Fi and 3G Wi-Fi offer free wireless Internet coverage, utilized on home wireless networks and Wi-Fi “hot spots” in public, but the DX does not. By contrast the 3G Wi-Fi and DX versions offer additional, global wireless coverage, which means that you have a wireless signal for your Kindle wherever a cellphone signal exists. This allows for maximum versatility and downloading capabilities while you're out and about and away from home or other publicly offered Wi-Fi locations.
The Kindle Wi-Fi and 3G Wi-Fi are the same size, measuring 7.5-by-4.8 inches and a slim 0.335-inches thick. They weigh in at 8.5 oz. and 8.7 oz., respectively. The DX is larger at 10.4-by-7.2 inches, and is only slightly thicker at 0.38 inches. It weighs twice what the other two do, but at 18.9 oz., still offers great portability.
Battery life is where the three Kindle models differ the greatest, due mostly to their connectivity options. With the wireless option turned off, the Wi-Fi and 3G Wi-Fi batteries last for two months, based upon a half-hour of daily reading time, and the DX lasts for two or three weeks, Amazon says. With the wireless turned on, the Wi-Fi version lasts the longest at three weeks, with the 3G Wi-Fi version lasting for a comparably short 10 days. The DX battery runs for seven days between charges.
Because the Wi-Fi and 3G Wi-Fi are essentially the same unit, just different wireless capabilities, their screen sizes are identical at 6 inches. The DX, being larger overall, contains a much larger screen at 9.7 inches. All three contain the glare-free, E Ink Pearl display, making for easier reading and contrast even in bright sunlight.