The back contains 5 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 days | Circular, concentric | Circular scale second in from the outer scale - refers to the full circle. |
| Saints' Days | Days of year | At each day days | Circular, concentric | Circular scale third in from the outer scale - refers to the full circle. |
| Shadow square | 1 - 12, Feet | Every 3 feet | Box | The lower two quadrants of the back of the instrument |