When the gap between your calf and boot is too large, snow and rain seep in and drench your socks. When boots are too big around the calves, the boots that won't stay up. Avoid these hassles and get a perfect pair of boots for your skinny calves.
Find a thin belt with a buckle or a sturdy piece of string in the same color and material as your boot.
Place the center of the belt or string at the lowest point on the back of your boot (while you're wearing them).
Bring the right side over to meet the left and cross the left side over the top so that it's now on the right. Repeat this criss-cross pattern carefully all the way up your boot.
Tie the end off in a bow, or secure the buckle as tight as possible, and test out the fit of your boots.
Search for a professional cobbler near you.
Bring your boots to the cobbler and obtain an estimate for resizing.
Wear the same socks you plan to wear with your boots and have the cobbler take measurements with your pant legs tucked-in. This will ensure that the boots are not sized down too much -- it's always better to have a bit of breathing room than end up with boots that pinch.