Trousers Waist Measurement - the measure is taken across trousers waist, you can also measure your favourite trousers waistband. The measure taken on body should be equal to the waistband from center to center / button closed. 

Hip Measurement - the measure is taken across hips over two fingers.

Trousers Outside Leg - the measure is taken alongside sideseam of your favourite length trousers including waistband.

Trousers 1/2 foot - the measure is the desired with of the trousers, you can compare the measure with your favourite trousers foot width.