The back contains 3 scales of the following types:
| Type (click to view scale details) |
Range & Units | Numbered | Geometry | Location |
|---|---|---|---|---|
| Degree | 0 - 90, Degrees | Every 10 degrees | Circular, concentric | The entire outer circle on the back of an astrolabe. |
| Unequal hours | 1/12 of daylight | Not numbered hours | Arc | Upper left quadrant (inside circular scales) |
| Unequal hours | 1/12 of daylight | Not numbered hours | Arc | Upper right quadrant (inside circular scales) |
| Shadow square | 0 - 12, Fingers | Every 3 fingers | Box | All four sides of the shadow square, commonly found in the lower half of the center of the instrument. |