The back contains 5 scales of the following types:
| Type (click to view scale details) |
Range & Units | Numbered | Geometry | Location |
|---|---|---|---|---|
| Zodiacal signs | Zodiacal sign | Circular, concentric | The entire outer circle on the back of an astrolabe. | |
| Calendar | Days of year | days | Circular, concentric | Circular scale immediately inside the outer scale - refers to the full circle |
| Equal hours | 1/12 of daylight | hours | Angle | Upper left quadrant of outer circular on back of instrument. |
| Equal hours | Times of day | hours | Angle | Lower left quadrant of outer circular on back of instrument. |
| Shadow square | 0 - 12, Fingers | Every 3 fingers | Box | Left hand vertical 'face' of the shadow square (in LL) |
| Shadow square | 0 - 12, Fingers | Every 3 fingers | Box | Left hand bottom face of the shadow square (in LL) |
| Shadow square | 0 - 12, Fingers | Every 3 fingers | Box | Right hand bottom face of the shadow square (in LR) |
| Shadow square | 0 - 12, Fingers | Every 3 fingers | Box | Right hand vertical face of the shadow square (in LR) |