We’ve heard the rumors that the new iPhone will be 7.6mm thick, but what does that actually mean? Obviously, it will be thinner than the outgoing iPhone 4S, but exactly how thin will it be?

Is there anything that we can use to get a good picture of how thin the new iPhone will be, before it’s officially unveiled in September? Well, actually, yes. And the good news is that you probably already have one in your possession.

The iPhone 4, without its back cover, just happens to be really close to 7.6mm. I removed the back cover of my iPhone 4 and compared it with the current-gen iPhone, tested how it felt in my hand, and measured it with a tape measure.

You might be surprised, but shaving off the back cover makes a significant difference when it comes to thinness. The iPhone 4 and iPhone 4S are already really thin devices, but this is on a whole new level. Couple this in with the fact that the new iPhone will have a 4″ screen, and you have a device that’s bound to feel quite different than its predecessor.

If the 7.6mm rumors prove to be true, then we can all once again marvel at Apple’s engineering efforts. The way they’re able to include even more features like an LTE radio, all while making it thinner and presumably preserving similar battery life, is some accomplishment.

If you have an iPhone 4 handy, then I advise you to look at the device and just imagine it without its back cover. If these rumors are true, then that’s a decent indication as to how thin the device will be.

If you want to go the extra mile and remove your back cover, then you’ll also be able to tell how the device might feel in hand. Granted, the missing back cover does make the iPhone 4 a smidgen lighter, but the removed width makes an obvious difference that you can feel for yourself.

What do you think about the rumors surrounding a thinner phone? It’s pretty much a given that the device will be thinner, but having actual numbers gives us a better indication as to what we can expect prior to its unveiling.