How deep do fence posts need to be in the ground?

We recommends that your fence posts should be dug into the ground by at least two feet (600mm).
This depth is standard across the fencing industry, with some experts advising deeper for fencing over seven feet (2100mm) in height.
See the table below for recommended post sizes
Fence Height | Post Length |
3FT (900MM) Including Gravel Board | 5FT (1500MM) Post Length |
4FT (1200MM) Including Gravel Board | 6FT (1800MM) Post Length |
5FT (1500MM) Including Gravel Board | 7FT (2100MM) Post Length |
6FT (1800MM) Including Gravel Board | 8FT (2400MM) Post Length |
7FT (2100MM) Including Gravel Board | 9FT (2700MM) Post Length |