Wooden fence post sizes: choosing the right timber
Updated: October 2026
Search for wooden fence post sizes on amazon.co.uk and you can quickly end up comparing a 300 mm border peg with a 95 mm square post. They are not interchangeable. Before looking at pack price or star ratings, decide whether you are marking out a bed, supporting a young tree or building a fence. Our [wood post comparison](/hub/paints-and-varnishes/wood-post) shows the eight listings side by side; this guide explains which dimensions belong to which job. The key is to allow for the timber below ground as well as the visible height, then check that the treatment claim suits contact with soil.
Search for wooden fence post sizes on amazon.co.uk and you can quickly end up comparing a 300 mm border peg with a 95 mm square post. They are not interchangeable.
Search for wooden fence post sizes on amazon.co.uk and you can quickly end up comparing a 300 mm border peg with a 95 mm square post. They are not interchangeable. Before looking at pack price or star ratings, decide whether you are marking out a bed, supporting a young tree or building a fence. Our wood post comparison shows the eight listings side by side; this guide explains which dimensions belong to which job. The key is to allow for the timber below ground as well as the visible height, then check that the treatment claim suits contact with soil.
Our top picks
| Badge | Product | Length | Section | Treatment claim | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Konrado-Garden Konrado-Garden 20 site pegs, 300 mm | 300 mm | 25 mm wide on the dimension line | Pressure treated in the bullets; disputed in reviews | 7.0 | about £19.49 | View offer |
 Gro Garden Products Gro Garden 10 stakes, 1.2 m × 32 mm | 1.2 m | 32 mm × 32 mm | Wolmanit CX, vacuum pressure | 8.4 | about £30 | View offer | |
 TG Supplies TG Supplies planed post, 95 × 95 mm × 1 m | 1 m | 95 mm × 95 mm | Pressure treated; no product name | 6.2 | about £23.99 | View offer |
On this page
Peg, stake or fence post?
A site peg is a short, pointed piece used for setting out lines, holding landscape edging or fixing low borders. The two Konrado-Garden packs in this comparison are 300 mm and a stated 400 mm long. Those dimensions can be useful around a bed, but they do not leave enough timber above ground after secure burial to support a panel or a newly planted tree.
A garden or tree stake is longer and usually slimmer than a fence post. The Gro Garden listings are titled at 900 mm × 25 mm and 1.2 m × 32 mm, while the P Dot Wolf pack is 2 ft, approximately 610 mm, by 45 mm. For guidance on depth, ties and removal, use our tree-staking guide.
A fence post must resist the panel acting as a sail, so both section and length matter. The 75 mm Austin Commerce and 95 mm TG Supplies squares look more like fence-post timber, but they are only 1.2 m and 1 m long.
Match the section and length to the fence
UK fencing merchants commonly suggest a 75 mm square post for everyday low fencing and a 100 mm square post for heavier, taller or more exposed panels. One merchant rule of thumb places 75 mm posts with panels up to about 1.2 m, and 100 mm posts with 1.5–1.8 m panels.
About 600 mm in the ground is a common starting point for a typical panel fence. A 1.8 m panel plus roughly 600 mm of buried post therefore points to a post around 2.4 m long. None of the eight products in this comparison is 2.4 m. The 1 m TG Supplies post would leave only about 400 mm above ground after 600 mm of burial, while the 1.2 m Austin Commerce length would leave about 600 mm.
The TG Supplies listing gives 95 × 95 mm and also calls the product 4x4. C24 on that listing is a strength grade, not a size or preservative class.
What the comparison can supply
For tree support and light temporary work, the 1.2 m × 32 mm Gro Garden ten-pack is the clearest fit in this set. Its listing names Wolmanit CX pressure treatment, although it does not print a Use Class. The 900 mm × 25 mm version is lighter and has a specification conflict: the title says 90 cm and ten pieces, while another line says 120 cm and the piece count says one.
The 2 ft × 45 mm P Dot Wolf pack has a thicker section but little length. The single 75 mm and 95 mm squares may suit a short repair where the existing above-ground height is modest. They do not solve a new 1.8 m boundary run.
Measure the timber when it arrives
Listing dimensions are not always borne out by the delivered pack. UK reviewers of the stated 400 × 25 mm Konrado pegs repeatedly report sections nearer 18–21 mm, and some also report lengths below 400 mm. Measure the length and both sides of the section before cutting, coating or installing anything. For treated timber, check the invoice for the required Use Class rather than judging treatment by green colour or smell.
Common questions
What size post should I use for a 1.8 m fence panel?
A 100 mm square post is a common merchant recommendation for a 1.5–1.8 m panel, particularly in an exposed position. Allow roughly 600 mm below ground as an initial rule of thumb, making a post around 2.4 m long for a 1.8 m panel. Soil, wind, gates and local design requirements can call for more.
Can I use a 25 mm garden stake as a fence post?
Not for a conventional panel fence. A 25 mm square stake can support plants, light mesh or temporary garden work, but it lacks the section expected for a panel exposed to wind. The 900 mm Gro Garden listing is also too short once any useful depth is driven into the ground.
Is a 95 mm post the same as a 4x4?
It is commonly sold as a nominal 4x4, but 95 mm is the finished dimension stated on the TG Supplies listing. Check the actual metric size if you need to fit a post shoe, cap or existing bracket. “4x4” does not tell you the post length, treatment class or suitability for burial.
Why might a 25 mm peg measure only 18–21 mm?
Some listings use nominal or inaccurate dimensions, and drying or planing can also reduce a finished section. In this set, several UK reviewers specifically report approximately 18–21 mm against a 25 mm Konrado title. Treat that as a product discrepancy and measure the delivered pack rather than assuming every piece is true to size.
Does this comparison include an 8 ft post?
No. Eight feet is approximately 2.44 m, close to the length often chosen for a 1.8 m panel with about 600 mm below ground. The longest listing here is 1.2 m. A fencing or timber merchant is the more suitable source when you need full-length posts and written ground-contact treatment details.
Do fence-height rules affect the post I buy?
They can. In England, Planning Portal guidance says permission may be needed above certain boundary heights, with a lower limit next to a highway. Rules and circumstances differ, so check the requirements for your property before buying a full run. Planning permission does not replace the need for suitable foundations and treated timber.
Related pages
Sources
Public UK sources used for the use-class, planting and planning points on this page. Prices, stars and review counts are from the amazon.co.uk listings on 16 October 2026.
- Wood Protection Association — Understanding Use Class 4 (retrieved 16 October 2026)
- Wood Protection Association — Make sure it’s 4 (retrieved 16 October 2026)
- Timber Decking and Cladding Association — timber preservation (retrieved 16 October 2026)
- Wood Protection Association — installing treated fence posts (retrieved 16 October 2026)
- RHS — How to stake a tree (retrieved 16 October 2026)
- Planning Portal — fences, gates and garden walls (retrieved 16 October 2026)
- NetRegs — wood preservatives (retrieved 16 October 2026)
- HSE — creosote renewal bulletin (retrieved 16 October 2026)