|Length:||2.3 miles (3.7 km)|
|Meets:||A1101, B1093, B1098|
|Route outline (key)|
The B1100 is a short B-road in the Fens.
The route starts on the A1101 in Welney, just to the north of the Old Bedford River. It then zigzags considerably in a vaguely westerly direction via Tipp's End to meet the B1093. Straightening out, the road then heads northwest past Christchurch to end on the B1098, which is running along the bank of the Sixteen Foot River.