The ratio of the feet to the circumference of the ankles is different with everyone. Unless you have your shoes custom designed, the straps will be an average size. Depending on the fit of the shoe this might be a problem. A shoe that otherwise fits perfectly may have straps that are too short. You can extend the straps of such shoes yourself in a few steps and with the right material no one will notice the alterations.
Preparation
Measure the length of your shoe strap.
Measure the circumference of your ankle.
Add an inch to the measurement of the circumference of your ankle. This is your ideal strap length.
Subtract the length of your shoe strap from your ideal strap length. This is the ideal length of your extension.
Using the ruler and the blade cut the leather to the ideal length of your extension.
Measure the width of your shoe strap.
Cut the sides of the leather to the width of your shoe strap using the ruler and the blade.
Thread the needle.
Tie the two ends of the thread in a knot.
Assembly
Sew the extension and the strap together using the needle with the thread by starting each stitch on the extension and ending on the strap.
When you are finished stitching, cut the thread off the needle.
Put a knot at the root of the thread.
Cut the remaining part of the thread.
Put on the shoe.
Mark where there needs to be a hole on the strap.
Make a hole on the mark with the hole puncher.