A method for automatic wire size modification comprising the steps of routing a wire to a source; detecting a first size differential between the wire and the source by calculating a first width difference between a length of the wire and a width of the source, and dividing the first width difference by the width of the source; detecting a second size differential between the wire and the source if the first size differential is less than a maximum length percentage by calculating a second width difference between the width of the source and a width of the wire, and dividing the second width difference by the width of the source; and modifying a size of the wire if the second size differential is less than a maximum width percentage.