Microsoft’s new Surface tablets have been all over the news this week, but now their lesser known details started appealing. One of them would be the price, that’s not known yet and another is the battery life that’s considered inferior to the one of the iPad, according to the estimations made by Computerworld.

Microsoft only revealed the watt-hour capacity of the batteries on the tablets, without estimations on how long they would run. As you know, battery life is critical for a portable gadget such as a tablet, so for Microsoft to leave that out was a strange move. So, moving on to determine how much battery life the Surface has, know that a 30 Wh rating means that the battery produces one watt of power for 30 hours, or 6 watts of power for 5 hours. Microsoft gave its slates a 31.4WH rating for the Windows RT version of the device and a 42 Wh rating for the more intensive Windows 8 Pro unit.

The latter runs on Intel CPU that’s certainly more power hungry than the Nvidia Tegra solution used on the other version. The current Apple iPad, offers a 42.5 Wh rating, meaning that it will last for 10 hours when browsing the web, watching movies and listening to music. To conclude the comparison, the Windows RT Surface battery is 25% less capacitous than the one of the iPad 3, so this means it will provide 7.5 hours of lifetime, a figure that even Android tablets can beat easily, either those made by Samsung or ASUS, for example.

The Surface Windows 8 Pro version will have a lifespan of 6 hours according to the analysis of the experts, so that’s a bummer too. However, you should still remember that these are merely speculations and we can’t tell till we test the product.