It’s minor but still important to compare sizes of the devices you maybe considering. Remember that even little differences particularly in weight can have an effect when you’re holding it or carrying it!

10" Tablets
Samsung Galaxy 10.1____ : 10.1"  x 6.9"  x 0.30" x 1.24 lbs
Apple iPad 3___________ :  9.5"  x 7.3"  x 0.37" x 1.45 lbs
Apple iPad 2___________ :  9.5"  x 7.3"  x 0.34" x 1.33 lbs
Apple iPad_____________ :  9.56" x 7.47" x 0.50" x 1.50 lbs
Lenovo Ideapad K1______ : 10.4"  x 7.4"  x 0.50" x 1.50 lbs
Asus Transformer Prime_ : 10.4"  x 7.1"  x 0.30" x 1.29 lbs
Asus Transformer_______ : 10.7"  x 6.9"  x 0.51" x 1.49 lbs
Motorola Xoom__________ :  9.8"  x 6.6"  x 0.51" x 1.61 lbs
HP Touchpad____________ :  9.45" x 7.48" x 0.54" x 1.65 lbs

7" Tablets
Kindle Fire____________ :  7.48" x 4.72" x 0.45" x 0.91 lbs
HTC EVO View 4G________ :  7.71" x 4.41" x 0.51" x 0.37 lbs
Nook Color_____________ :  8.10" x 5.00" x 0.48" x 0.99 lbs
Google Nexus 7_________ :  7.81" x 4.72" x 0.41" x 0.75 lbs

Phones
Motorola RAZR__________ :  5.15" x 2.71" x 0.28" x 4.4 oz
                           screen size: 4.3" 960x540 pixels

Samsung Galaxy S III___ :  5.38" x 2.78" x 0.34" x 4.7 oz
                           screen size: 4.0" 800x480 pixels

Apple iPhone 4S________ :  4.50" x 2.31" x 0.37" x 4.9 oz 
                           screen size: 3.5" 960x640 pixels

Apple iPhone 3GS_______ :  4.50" x 2.40" x 0.48" x 4.8 oz
                           screen size: 3.5" 480x320 pixels