The core of TA's technology is the ability to measure a true surface area of the wound, which is different from length multiplied by width. TA has published results showing that this method is significantly more accurate than the length times width estimation for area. However, if you are comparing your length and width measurements to the TA length and width measurements, and they still disagree, there are a few things that you can verify: The wound margins may be incorrect : If the wound margins are incorrect, you can retrace the wound margins. The camera is not oriented correctly and the measurements are in "Compass" mode : TA defines compass mode as measuring the wound from head-to-toe for length and side-to-side for width. This is the most popular method. However, the TA software assumes that the top of the camera screen is pointing towards the head of the patient. If this is not the case, the length and width measurements may differ from your ruler measurements using the same method.