What is the standard post spacing for post and rail fencing?

The standard spacing for post and rail fencing in the UK is 2.4m (8ft) between posts. For more robust fencing or on sloping ground, closer spacing of 1.8m (6ft) is recommended. On flat ground with lighter loads, 3.0m spacing can work but may cause rails to sag over time.

How many rails should I use for my fence?

Two rails are suitable for low boundary fences up to 0.9m. Three rails are the standard for most post and rail fences at 1.2m height, providing good strength and appearance. Four rails are used for taller fences (1.5m+) or where extra strength is needed, such as horse paddocks.

What size timber posts should I use?

For standard garden post and rail fencing, 75×75mm posts are adequate. For agricultural fencing, paddocks, or where stock wire will be attached, use 100×100mm posts for extra strength. All posts should be pressure-treated to UC4 standard for ground contact use. Use our concrete for fence posts calculator (/fencing/concrete-for-fence-posts-calculator/) to work out postcrete or concrete quantities for setting each post.

Can I add stock wire to post and rail fencing?

Yes, stock wire mesh is commonly attached to the field side of post and rail fencing to contain livestock or pets. Standard stock wire comes in 50m rolls. You will need fencing staples (U-nails) to fix the wire to the posts and rails. For sheep, use C8/80/15 wire; for cattle, use C8/80/30.

How long do post and rail fences last?

A well-installed post and rail fence using pressure-treated (tanalised) timber should last 15-20 years. Posts are the first component to deteriorate as they sit in the ground. Using concrete or postcrete to set posts, and ensuring good drainage around the base, will maximise lifespan. Softwood rails typically last 10-15 years.

Post and Rail Fence Calculator — Posts, Rails & Wire

Calculate posts, rails, postcrete and wire mesh for post and rail fencing. Ideal for gardens, paddocks and rural boundaries in the UK.

Total Fence Run Length

Total length of fencing needed

Fence Height

Select the fence height for your calculation

Number of Rails

Select the number of rails for your calculation

Post Spacing

Centre-to-centre distance between members

Post Type

Concrete posts last longer; timber is easier to work with

Rail Length

Select the rail length for your calculation

Include stock wire mesh

Add wire mesh for livestock or pet containment

Include wastage allowance

Adds 10% extra for cutting waste and off-cuts

Wastage Percentage

10% is standard for post and rail fencing

Price Per Post (optional)

Enter your supplier price for a cost estimate

Price Per Rail (optional)

Enter your supplier price for a cost estimate

Price Per Postcrete Bag (optional)

Enter your supplier price for a cost estimate

How We Calculate This

Our post and rail calculator works by dividing your fence run length by the post spacing to determine the number of posts, then calculating the total rail length based on the number of rails you select.

The formula

Posts = (Fence length ÷ Post spacing) + 1 (rounded up)
Rails = (Fence length × Number of rails) ÷ Rail length (rounded up)
Post length = Fence height + 600mm (burial depth)

For example, a 20m fence run with 2.4m spacing needs: (20 ÷ 2.4) + 1 = 9.33, rounded up to 10 posts. With 3 rails using 3.6m lengths: (20 × 3) ÷ 3.6 = 16.67, rounded up to 17 rails.

Post and rail fencing tips

Use UC4 pressure-treated timber for all ground contact posts
Rails should overlap at posts — do not butt them end to end between posts
On sloping ground, use closer post spacing and step the rails
Pre-drill nail holes in hardwood rails to prevent splitting
For paddock fencing, place rails on the inside so stock pushes against posts

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Verify with your supplier.