You may want to measure your biceps for one of two reasons: either you’re measuring the size of your muscles for body building, or being fitted for a dress shirt. If you’re measuring to see the circumference of your muscle, you should either measure alone or ask a friend (or gym buddy) to assist. If you’re being fitted for a shirt, you’ll need to be measured by a tailor, or at least have a friend help you. For either type of measurement, you’ll need a tailor tape measure.

Method 1
Method 1 of 2:

Measuring Your Bicep for Muscle Size

  1. 1
    Measure before you weight lift. If you’ve exercised your arms right before you measure your bicep size, you won’t get an accurate bicep measurement. Working out forces blood into your muscles, which temporarily inflates the size of your biceps and triceps.[1]
    • If you’re planning to measure your arms and work out in the same day, always take the measurements first.
  2. 2
    Measure at the thickest part of both biceps. Wrap a tape measure around both your biceps at their thickest point, near your armpit. Measure one arm after the other. Measuring both biceps will help you compare your arms against each other, and figure out if you need to work one more than the other.[2]
    • Ideally, both biceps should be the same size.
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  3. 3
    Hold the measuring tape flat against your skin. For accurate, consistent measurements, make sure that the material of the tape measure is flat against your skin. Don’t pull or distort the tape, or you’ll risk stretching it and distorting your measurement. Make sure that there are no twists or bumps in the tape when you’re measuring.[3]
    • You should also never measure your bicep through a shirt. If you’re wearing a t-shirt, roll the sleeves up. Otherwise, remove your shirt so that you’re measuring directly against the skin of your arm.
  4. 4
    Do not flex your biceps while measuring. You’ll get reliable and consistent measurements if you measure your bicep when it’s relaxed. Let your arm hang down beside your body, and keep your muscles relaxed while measuring them.[4]
    • Consistency is the most important part of measuring any body part for bodybuilding, and it’s easier to get consistent measurements if you don’t flex.
    • Your muscles will flex different amounts from day to day, so measuring the relaxed muscles will provide the most accurate results.
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Method 2
Method 2 of 2:

Measuring the Bicep for a Shirt Fitting

  1. 1
    Wear a light shirt. It’s fine to have your bicep measured in a t-shirt or other thin material that won’t add to the measured circumference of your bicep.[5] If you wear a heavy-weight fabric, it will distort the measurement.
    • If you’re measuring in an informal setting with a friend, you could take off your shirt altogether. This would be too informal for a tailor shop or a department store, though.
  2. 2
    Stand with your arms hanging by your sides. When having your bicep measured, your arms should be completely relaxed and hanging loose by your sides. Keep your upper body as relaxed as possible while being measured.[6]
    • If the tailor requests, you may need to extend your arm out to the side so that they can fit the tape measure around them. Return your arm to your side once the tape measure is around it, though.
  3. 3
    Measure the bicep at the fullest point. To ensure that your shirt fits properly, the bicep measurement should be taken around the thickest part of your bicep. This point will probably be high up on your arm, only about 2 inches (5.1 cm) below the armpit. Use a soft tailor tape measure to take the measurement.[7]
    • This is where any tailor will measure your bicep. If you’re being measured by a friend who hasn’t measured someone’s arm before, make sure to specify where your bicep should be measured.
  4. 4
    Do not flex your bicep. You may be tempted to flex your bicep in order to make it appear as though you have a large-circumference arm. Resist this temptation, though—while flexing may be appropriate in some settings, it will distort the bicep measurement for your shirt.[8]
    • If you do flex while the measurement is being taken, you’ll end up with a shirt with awkwardly roomy, baggy sleeves.
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About This Article

wikiHow Staff
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This article was co-authored by wikiHow Staff. Our trained team of editors and researchers validate articles for accuracy and comprehensiveness. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. This article has been viewed 137,596 times.
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Co-authors: 5
Updated: June 8, 2020
Views: 137,596
Categories: Body Measurements
Article SummaryX

To measure your biceps, do it before you lift weights since working out temporarily inflates the size of your muscles. To get started, wrap a measuring tape around the thickest part of one of your biceps, making sure it's against your bare skin and not over your clothes. Then, holding the measuring tape flat against your skin so there are no twists or bumps, note the measurement on the measuring tape. Try to keep your biceps relaxed when you measure them, and avoid flexing since it will give you an inaccurate measurement. To learn how to measure your biceps for a shirt fitting, scroll down!

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