But we've got a trick that's never failed us: When you're seated or standing in the position you'd use the desk, rest your arms at your sides, keeping your elbow at a 90 degree angle and your upper arms in line with your torso. If the desk is the right height, your hands should rest comfortable on the desk.
If it's not just right, you're signing yourself up for a lifetime of back, neck and shoulder strain. Better to get the right desk now than regret it as you're cursing your sore shoulders later.
But if you're finding that your desk at home doesn't fit the bill, don't stress. If you can't change your desk, change your chair. Mess with your desk chair's adjustments or shop around for a new one that puts you at the right height for your office.