Sizes vary from make to make. Sometimes the variations are very slight, sometimes they can be significant. Also, some brands are known as "generous" others aren't. I'm afraid you just have to get to know the different makes and their sizing.

However, most conform to the following basic measurements.

2XL 3XL 4XL 5XL 6XL 7XL 8XL 9XL Collar                 Inches 18 - 18 1/2 19 - 19 1/2 20 - 20 1/2 21 - 21 1/2 22 - 22 1/2 23 - 23 1/2 24 - 24 1/2 25 - 25 1/2 cm 46 - 47 48 - 50 51 - 52 53 - 55 56 - 57 58 - 60 61 - 62 63 - 64 Chest                 Inches 46 - 48 50 - 52 54 - 56 58 - 60 62 - 64 66 - 68 70 - 72 74 - 76 cm 117 - 122 127 - 132 137 - 142 147 - 152 157 - 163 168 - 173 178 - 183 188 - 193 Waist                 Inches 44 - 46 48 - 50 52 - 54 56 - 58 60 - 62 64 - 66 68 - 70 72 - 74 cm 112 - 117 122 - 127 132 - 137 142 - 147 152 - 157 163 - 168 173 - 178 183 - 188 UK Shoes European Shoes USA Shoes 11 45 - 46 11 1/2 12 46 - 47 12 1/2 13 47 - 48 14 14 48 - 49 15 15 49 - 50 16 16 50 - 51 17

To measure yourself accurately you will need a flexible / cloth tape measure, sometimes known as a tailors tape measure. Do not use a metal builders tape measure as the sizes wont be accurate enough. If possible get someone else to measure you, it makes the whole process much easier.

COLLAR - Place the measuring tape around the fullest part of your neck and keep the tape snug but not tight. For a comfortable fit, place 2 fingers between the tape and your neck. Round up to the next 1/2". Note down the measurement. CHEST - Take measurements the under armpits, around the fullest part of chest and shoulder blades. Allow 2" for comfort. Note down the measurement. WAIST - Measure around where you normally wear your trousers, keeping the tape measure a bit loose or putting one finger between your body and the tape measure. Note down the measurement. INSIDE LEG - You'll need a friend to measure from your crotch to where you want your trousers to end, to the top of the shoe in the front and just above the heel in the back (you'll need to be wearing shoes for this one). Note down the measurement. Easier method: Find a pair of good fitting trousers, and measure from crotch seam to bottom of the trousers. Note down the measurement.