Linear measurement upon Barsoom has been defined, and redefined a couple of times within the Martian novels. It seems in earlier works some mistakes were made in the conversion of Barsoomian measurement into American. The following is the most 'definitive' version, as taken from the Burrough's Cyclopaedia.
A karad is a Martian unit of distance or latitude: for distance, 1 karad is 100 haads, or approximately 36.9 miles; for latitude, there are 360 karads around the circumference of Mars, permitting any location to be discerned as a number of karads east or west from a prime meridian and another number of karads north or south of the equator.
A haad is a Martian equivalent of a mile (1,949 feet), it is equal to 200 ads.
An ad is made up of 10 sofads (9.745 feet).
A sofad is the Martian equivalent of a foot, it is roughly 11.694 Earth inches and made up of 10 sofs.
A sof is a the Martian 'inch', which is approximately 1.1694 inches.
| UNIT | Sof | Sofad | Ad | Haad | Karad |
| Sof | 1 | .1 | .01 | ? | ? |
| Sofad | * | 1 | 10 | 2,000 | 200,000 |
| Ad | * | * | 1 | 200 | 2,000 |
| Haad | * | * | * | 1 | 100 |
| Karad | * | * | * | * | 1 |
Notes[]
- According to Marvel's Warlord of Mars issue 24, a sof is 1.17 inches (or 1/10th of a sofad).