In unveiling the new PlayStation 4 and its DualShock 4 controller tonight, Sony notably neglected to include any information about the precise size of that new touchpad sitting front and center on the face of the redesigned controller. But we didn't let that stop us. Using publicly available information and press photos of the controller, Ars has been able to generate an estimate of that touchpad's size: 52-54mm (2.04"-2.12") across and 23-29mm (0.9"-1.14") high.

Here's how we did it (if you want to check our math, feel free):

We started with the high-quality front-facing image of the controller posted by Sony on its Flickr stream (and shown above). The controller portion of this photo is approximately 1428 x 898 pixels.

We know from press materials released by Sony tonight that the DualShock 4 currently measures 162mm x 98mm (with a depth of 52mm). Using a little math, we can figure out that one pixel in this image is anywhere from .1091 (based on the widths) to .1134 millimeters (based on the heights). This means the height/width ratios in the controller and our cropped image don't match precisely, but they're close enough for government work.

Tracing out the precise touchpad area on the image was a little tricky, because it's not totally clear where the touchpad ends on any side. As you can see in the image above, there's a small bezel on the sides and bottom of the touchpad area that may or may not be touch-sensitive. On the top edge, it's also not entirely clear where the touch sensitive area ends and the LED "light" area begins. A series of faint dots on the touchpad suggests a natural border, but we can't be sure that the touch-sensitive material doesn't extend any higher.

Taking all of that into account, we traced two rectangles on the original image: one outlining what seemed to be the minimum possible touchpad area and another tracing its potential maximum. These rectangles measured 460 x 210 pixels and 478 x 265 pixels, respectively.

Using our per-pixel conversions from the first two steps, we get these estimated touchpad size ranges (all rounded to the nearest millimeter for simplicity): 52mm x 23mm (2.04" x 0.9") for the small box and 54mm x 29mm (2.12" x 1.14") for the big box. The diagonal "screen size" of the touchpad is 57mm (2.24") for the small box and 61mm (2.4") for the big box. The surface area of the touchpad is 1196mm 2 (1.84in 2 ) for the small box and 1566mm 2 (2.42in 2 ) for the big box.

For simplicity, none of these measurements take into account the small "rounded corners" at the bottom of the touchpad area or the curved back top of the "big box." Calculating these effects is left as an exercise for the reader.

Sony has made it clear that the specs for all of the PS4 hardware are subject to change at any time, so this information might not even be valid by the time the PS4 launches. There's also some margin of error here, of course, owing to the vagaries of estimating sizes based on photos and accurate cropping.

Still, it gives a good rough idea of the usable area we're talking about here, which is a decent bit smaller than most smartphone touchscreens (which range from a 3.5" diagonal for the iPhone 4S to a 6.1" diagonal for one of Huawei's "phablets"). It's also much smaller than the 5" or so diagonal trackpad on the 13" Macbook Air, and obviously much smaller that the Wii U's 6.2" diagonal GamePad screen (which is an entirely different animal, to be sure). Keep these numbers in mind the next time you imagine playing Angry Birds on your super-high-powered, next-generation living room console.