The back contains 5 scales of the following types:
| Type (click to view scale details) |
Range & Units | Numbered | Geometry | Location |
|---|---|---|---|---|
| Altitude | 0 - 90, Degrees | Irregularly in each quadrant degrees | Circular, concentric | The entire outer circle on the back of an astrolabe. |
| Zodiacal signs | Aries - Pisces, Degrees | At 10°, 30°, 60° and 90° degrees | 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 | Last day of the month days | Circular, eccentric | Circular scale second in from the outer scale - refers to the full circle. |
| Unequal hours | 1 - 6, Times of day | Every 1 hours | Arc | The upper two quadrants of the back of the instrument |
| Shadow square | 1 - 12, Fingers | Every 4 fingers | Box | All four sides of the shadow square, commonly found in the lower half of the center of the instrument. |