The back contains 7 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. |
| Zodiacal signs | 0 - 30, Zodiacal divisions, equal or unequal | Every 10 | Circular, concentric | Circular scale immediately inside the outer scale - refers to the full circle |
| Calendar | First day of month - Last day of month, Days of year | Every 10 and end of month days | Circular, concentric | None |
| Unequal hours | 0 - 12, 1/12 of daylight | Every 1 hours | Arc | The upper two quadrants of the back of the instrument |
| Equal hours | 0 - 12, Times of day | Every 1 hours | Arc | The upper two quadrants of the back of the instrument |
| Shadow square | 0 - 12, Fingers | Every 1 fingers | Box | The lower two quadrants of the back of the instrument |
| Shadow square | 0 - 60, 1/60 of quadrant radius | Every 10 | Box | The lower two quadrants of the back of the instrument |