We have found Mini Boden trousers sizing to be a bit erratic. On average, they tend to size small in the leg length but occasionally you get a pair that size long so always best to check with your seller for the measurements. We buy a LOT of Boden items as the quality is fantastic but you do have to be a bit savvy on the trouser length.
We have found the sweatpants and the velvet bootlegs to be very prone to shrinking so we never tumble dry ours. If buying second hand, always check with the seller for the leg length. Cords and jeans don't shrink but our daughter often wears two different sizes at the same time!
Dresses tend to come in short length (mid thigh) or below the knee, and many skirts sit just above the knee but a few are designed to be quite short so don't ever be afraid to ask your seller for those important mesurements. You can tell a lot about your seller from their response as well.
Up to a 2 - 3 tends to have elasticated waist and then from 3 - 4 tends to have adjustable waist bands, via internal elastics. Baggies and sweatpants normally only have elasticated waists.
Anyway this is Boden's size guides:
BODEN SIZE GUIDE
Age Height Chest* Waist* Hip
2 - 3 90 - 98cm 54cm 50cm
3 - 4 98 - 104cm 56cm 52cm
4 - 5 104 - 110cm 58cm 53.5cm
5 - 6 110 - 116cm 60cm 55cm
7 - 8 116 - 128cm 64cm 58cm
9 - 10 128 - 140cm 69cm 62cm 76cm