Post mix calculator
Estimate how many bags of post mix you need for standard fence posts and gate posts. This calculator uses a simple practical guide based on the number of post holes.
How much post mix do I need?
Enter the number of standard fence posts and gate posts, then select whether the fence is in a normal garden or an exposed, windy site. The calculator will estimate the number of post mix bags needed.
Your post mix estimate
Use this as a starting point for planning. The estimate is based on 2 bags per standard post hole, or 3 bags per hole for gate posts and exposed or windy sites.
| Item | Estimate | Notes |
|---|---|---|
| Standard fence posts | 0 | Calculated at 2 bags per standard post hole. |
| Gate posts | 0 | Calculated at 3 bags per gate post hole. |
| Fence height | 5ft to 6ft | Standard fence height selected. |
| Site exposure | Normal garden | Standard fence posts calculated at 2 bags per hole. |
| Standard post mix | 0 bags | Estimate for standard fence posts based on selected exposure. |
| Gate post mix | 0 bags | Estimate for gate posts at 3 bags per post hole. |
| Total post mix estimate | 0 bags | Estimated total number of bags. |
Recommended next steps
Once you have your estimate, choose the post mix, fence posts and gate posts needed for your project.
How this post mix calculator works
This post mix calculator estimates the number of bags needed for standard fence posts and gate posts. It uses 2 bags of post mix per standard fence post hole, or 3 bags per hole for gate posts and exposed or windy sites.
Gate posts normally need more support because they carry the weight and movement of a gate. Exposed or windy gardens also need a stronger footing around each post, so the calculator uses 3 bags per hole for those conditions.
How much post mix do I need per fence post?
For standard garden fencing in normal conditions, this calculator uses 2 bags of post mix per fence post hole. Exposed or windy sites are calculated at 3 bags per hole.
How much post mix do I need for gate posts?
Gate posts usually need more support than standard fence posts because they carry the weight and movement of the gate. This calculator uses 3 bags of post mix per gate post hole.
| Post type or condition | Planning guide | Notes |
|---|---|---|
| Standard fence post | 2 bags per post hole | Used for standard garden fencing in normal conditions. |
| Gate post | 3 bags per post hole | Gate posts need extra support due to gate weight and movement. |
| Exposed or windy garden | 3 bags per post hole | Exposed fencing usually needs a stronger footing around each post. |
Things that can affect post mix quantities
The number of bags needed can change from one job to another. Hole width, hole depth, post size, soil type, drainage, fence height and wind exposure can all make a difference. For heavy gates and awkward ground, check the installation carefully before ordering.
Post mix calculator FAQs
How much post mix do I need per fence post?
For standard garden fencing in normal conditions, allow 2 bags of post mix per post hole. For exposed or windy gardens, allow 3 bags per post hole.
How much post mix do I need for gate posts?
Gate posts are calculated at 3 bags of post mix per hole because they need more support than standard fence posts.
Is one bag of post mix enough per post?
For most standard fence post holes, this calculator uses 2 bags rather than 1. A single bag may not give enough allowance once hole size, depth and ground conditions are considered.
Does fence height affect how much post mix I need?
Taller fences can put more strain on posts, especially in exposed gardens. This calculator keeps the quantity simple, but it is worth checking hole size and post length carefully for taller fences.
Do windy gardens need more post mix?
Yes. For exposed or windy gardens, this calculator uses 3 bags per post hole to allow for a stronger footing around each post.
Can I use this calculator for wooden and concrete fence posts?
Yes. This calculator gives a general post mix estimate for standard wooden fence posts, concrete fence posts and gate posts. The exact amount needed can still vary depending on the post size and hole size.