If you want to be well-dressed, nothing looks better than a properly cut suit. Suits should be flattering and sophisticated, giving you a sense of keen professionalism and style. Taking the time to measure yourself for the best fitting suit before purchasing it will save you time and money, as well as ensure you get the appropriate size. You can learn to measure the jacket, the trousers, and some tips to help you make sure the suit fits properly.
Part 1 of 3: Measuring the Jacket
1. Measure your total height and weight. Anytime you're buying a suit, whatever the style and the size, it's a good idea to take a recent measurement of your height and weight to provide. While the individual measurements associated with the suit are also important to get the right fit, basic height and weight are good ways to get in the ballpark.
· This is especially important if you're going to have your suit tailored, because height and weight helps tailors determine your “drop” of the suit, which is the difference between the size of the pants and jacket. It'll help the suit be tailored more quickly.
2. Wear a dress shirt when measuring for a suit. It's important to be wearing the type of shirt you might be wearing under a suit while you're taking measurements for a suit. The shoulder seam in the shirt can serve as a vantage point when measuring the width of your shoulders or your arm length, and the bulk of the shirt will help ensure that your jacket isn't too snug.
3. Measure your over-arm shoulder width. The over-arm measurement will help to create the width of the entire jacket, from shoulder-to-shoulder. Start your tape measure at the back corner of one shoulder, just below where you clavicle ends. Run it across the top of your shoulders, behind your neck and to the back corner of the other shoulder.
When determining measurements, don't pull the tape measure tight. Instead, make sure it fits snugly around the body part(s) you're measuring. Pulling the tape measure too tight will result in a suit that is too tight.
4. Measure your chest. The chest is an essential measurement to get the right body-fit and flattering cut for the jacket. To take it, raise both arms and run the tape measure around the fullest part of your chest, underneath both your arms. Lower your arms to record the measurement once the tape measure is in place.
Don't flex your chest muscles when figuring out your chest measurement. Flexing your muscles could result in overinflated chest measurements and your suit will not fit well.
5. Measure your arms. Start your tape measure from the same point on your shoulder where you measured your shoulder width. Slide your tape measure down your arm to your wrist.
You also may need to provide your coat in-sleeve measurement, while wearing a jacket. Put the tape measure on the inside of your arm, slightly below your wrist. Pull the tape up into your underarm for the complete measurement.
6. Measure your neck. If you're going to also buy or rent a dress shirt, it's also important to take a neck measurement. Wrap the tape measure around the bottom of your neck, just above your collar bone, where your collar would be normally. This will help you find a shirt that fits properly.
Part 2 of 3: Measuring the Pants
1. Always wear shoes when measuring for pants.
Because dress shoes change the way you stand slightly, as well as giving you a little extra added height, it's important to wear dress shoes, the type of which you may wear with the suit, while you're measuring for the pants, to help you take accurate measurements.
2. Measure your hips.
To get the right waist size of the pants, measure the widest part of your hip bones. Wrap the tape measure all the way around the points of your hips, generally where your pants normally sit.
Measure your waist as well. Depending on the style of the pants, you may or may not need to take your waist measurement, so it's a good idea to bring it along to the store anyway. Find a starting point slightly above either hip bone along your waistline. Loop the tape measure around your waist and back to your starting point to help get an accurate measurement for the waist of the suit pants.
3. Measure your outseam.
The outseam is the measurement of the outer-most leg of your pants, trailing down from your hip to your ankle. To take the measurement, stand with your back as straight as possible and measure from your belt-line to the side of your foot in shoes.
4. Measure your inseam.
While wearing appropriate shoes, begin the measurement at the top, inside part of your leg where your leg meets your groin. Run the tape measure down the inside of the leg to a point near the middle of your foot.
It's also possible to take this measurement on a pair of pants that you already have that fit you well. Lay the pants out on a flat surface, hip side down. Fold one pant leg out of the way and measure down the entire length of the inseam.
Source : http://www.wikihow.com/Measure-for-a-Suit