What size pants for a 113 lbs girl?

The below answer doesn't actually answer the question of average >> How to measure for your pants / trouser size :

Men : While standing straight, have a friend measure around your waist (W) at the top of your hip bone. Again, don't pull too tight to allow for eating and seating room. Also, if you know you have large hips in relation to your waist it may be advisable to size up as well.

Pants Length / Out-seam : While standing straight & looking forward measure from the top of the hip bone down to "approximately" the bottom of the ankle bone. We ship a vast majority of our pants unhemmed. We can alter the pants length upon special request for an additional fee. However, if we hem the pants they are no longer return/exchangeable.

Men's Adjustable Pants have a 3" range of adjustment.

Men's Adjustable

Pants Size Scale27-28-2930-31-3233-34-3536-37-3839-40-4142-43-4445-46-4748-49-5051-52-5354-55-5657-58-5960-61-62

Women : please refer to the size scale below to determine your correct pants size.

Women's pants, skirts

and shorts size scale 2= 24.5 waist -35.5 hip4= 25 waist -36 hip6= 26 waist -37 hip8= 27 waist -38 hip10= 28.5 waist -40 hip12= 30.5 waist -42 hip14= 32.5 waist -44 hip16= 34.5 waist -46 hip18= 36.5 waist -48 hip20= 38.5 waist -50 hip22= 40.5 waist -52 hip24= 43 waist -55 hip26= 45 waist -57 hip28= 47 waist -59 hip

Tip : When in doubt...Always size up.