Disk loading ignores blade chord. It's simply the gyro's weight divided by the area swept by the blades. This area is a shallow cone in normal flight, but we approximate it to be a flat disk. Disk loading is one statistic to use in analyzing rotors. It's measured in pounds per square foot. For small gyros, disk loadings around 1.5 lb./sq. ft. seem about right.
It's pretty obvious that blade chord matters, though. Blades are wings, after all, and their area matters a whole bunch in fact -- just as much as chord matters for any other wing.
To capture the effect of chord, we use two other calculations.
One is "blade loading." This is figured in the same way as wing loading for an airplane -- aircraft weight divided by blade area. It tends to come out in the range of 40-50-60 lb./sq. ft. For example, a small, Bensen-style gyro with blades of 7" chord and 23 - foot diameter, grossing at 550 lb., would have a blade loading of 41 lb/sq. ft.
The other stat is "disk solidity." This is the ratio between blade area and disk area. Our little gyro with the 7" x 23 ft. rotor would have a solidity of 0.032.
To over-simplify: We juggle these stats in designing our rotors so that our blade tip speed is not so high that the compressibility of the air itself starts to eat too much power, and so that the blades operate at their most efficient angle of attack -- neither stalled nor down at 1-2 degrees.
Many of the heavier homebuilt gyros are under-rotored by any of these measures. They use brute horsepower to (inefficiently) batter their way through the air, gulping fuel, making a godawful racket and straining light frames that weren't intended for such use. E.g. the Air Command and Bensen-Brock frames were designed around 40-50-60 hp 2-strokes weighing about 75 lb.