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Fence posts in four sections and five lengths
Choose the section for the job and a length that leaves enough in the ground. As a starting point, a post wants roughly a third of its length below ground, or a little more on exposed runs.
Matching post length to fence height
A guide for posts set in post mix. Exposed or soft ground may need a deeper footing.
| Fence height | Post length | Usual section |
|---|---|---|
| 1.2m | 1.8m | 3x3 or 4x3 |
| 1.5m | 2.1m | 4x3, or 4x4 if exposed |
| 1.8m | 2.4m | 4x3, or 4x4 if exposed |
| 2.1m | 3m | 4x3 or 4x4 |
| 2.4m | 3m | 4x4 |
3x3, 4x3 or 4x4?
3x3 (75 x 75mm) suits low or sheltered fences and post-and-rail work. 4x3 (100 x 75mm) is the common choice for closeboard, stiffer along the run without the weight of a 4x4. 4x4 (100 x 100mm) is the heavy option for exposed boundaries, corners, ends and the posts either side of a pedestrian gate.
For hanging a gate, use the 6x6 gate post. Most gates need one each side.
Price the whole run in one go
Put in the length and height and the calculator lists the posts, rails, boards and post mix, ready to add to your basket.
Questions
How many posts do I need?
With posts every 1.8m, divide the length of the run by 1.8, round up, and add one. The fence calculator does this for you and adds post mix too.
How much post mix per post?
As a guide, one 20kg bag for a 3x3 or 4x3 post and two for a 4x4. Bigger holes and gate posts take more.