Fence Panel Calculator
Fencing a garden boundary means getting your panel count, post count and postcrete right before you start digging — too few materials means a wasted trip back to the shop, too many means money sat unused in the shed. Enter the total length of your fence run and your panel size below and we'll work out exactly how many panels, posts and bags of postcrete you need, plus a few well-reviewed garden essentials to go alongside the job.
Enter your fence run
Tell us the total length of fencing you need and the panel size you plan to use.
Enter a fence length above to see how many panels, posts and bags of postcrete you'll need.
Recommended for your garden
A few well-reviewed options to go alongside your fencing project.
Currently unavailable
Pros
- Traditional overlap timber cladding
- Budget-friendly for the size
- Includes windows for natural light
Cons
- Requires annual timber treatment
- Wood
- Small gardens
- 8x6ft
£449.99
Pros
- 8mm overlap cladding handcrafted from sustainable timber
- Felt and fixings included
- Windows for natural light
Cons
- Requires annual timber treatment
- Base not included
- Resin
- Small gardens
- 145x82x125cm
Currently unavailable
Pros
- Weatherproof resin construction, no rot or rust
- Lockable doors and piston-assisted lid
- Compact footprint good for patios and small gardens
Cons
- Smaller capacity than a full-size shed
Frequently asked questions
Do I need my neighbour's permission to replace a shared fence?
You don't normally need permission to replace a fence on your own side of a boundary, but if the fence or its posts sit directly on the boundary line or are jointly owned, it's good practice — and can avoid disputes — to discuss the work with your neighbour first, especially if you need temporary access to their side to fit posts or panels.
How deep should fence posts be?
As a general rule, bury around a third of the total post length in the ground, with a minimum hole depth of about 600mm (60cm) for a standard 1.8m panel fence. Deeper holes, around 750mm, are safer on exposed or windy sites to stop posts leaning over time.
Concrete or postcrete for fence posts?
Postcrete (fast-setting fence post concrete) is the easier option for most DIY jobs — you pour it dry around the post with some water and it sets rigid in minutes, holding the post in position while you work. Traditional mixed concrete is cheaper for large jobs but needs mixing, more care to keep posts aligned, and longer to cure.
How many bags of postcrete does one fence post need?
For a standard post hole of around 300mm x 300mm x 600mm, two 20kg bags of postcrete is a reasonable estimate for most residential fence posts, though larger or deeper holes for taller fences may need three.
How this calculator works
The calculator divides your total fence run length by the width of the panel you choose to get the number of panels needed, rounding up to the nearest whole panel since you can’t buy part of one. It then adds one extra post for the end of the run, giving you a total of panels + 1 posts. Finally, it multiplies the post count by 2 bags per post to estimate the postcrete required.
The two standard panel widths in the UK are 1.83m (6ft) and 0.91m (3ft). The 1.83m panel is the most common for full-height boundary fencing, while the narrower 0.91m panel is useful for filling gaps, building shorter fences, or working around awkward lengths where a full 6ft panel would leave an untidy sliver at the end.
UK fence panel sizes and typical uses
| Panel size | Width | Panels per 10m run | Typical use |
|---|---|---|---|
| Standard | 1.83m (6ft) | 6 panels | Full-height boundary fencing |
| Narrow / gap-filler | 0.91m (3ft) | 11 panels | Short runs, infill panels, low fences |
Worked example: A 12m boundary fence with standard 6ft panels
For a 12m fence run using standard 1.83m panels, the calculator works out 12 ÷ 1.83 = 6.56, rounded up to 7 panels. You then need 7 + 1 = 8 posts (one at each end and one between every pair of panels). At 2 bags of postcrete per post, that’s 8 × 2 = 16 bags total.
If you used 0.91m narrow panels instead, the same 12m run would need 12 ÷ 0.91 = 13.19, rounded up to 14 panels, plus 15 posts and 30 bags of postcrete. Narrow panels are useful for filling awkward gaps, but they mean more posts, more concrete, and more labour overall — so they’re best reserved for short runs or infill sections rather than a full boundary fence.
Common mistakes when buying fencing materials
- Measuring the fence run along the ground instead of the horizontal length. On a sloping site, the actual fence length follows the slope, not the flat horizontal distance — measure with a tape along the proposed fence line, not on a map.
- Forgetting that posts sit between panels, not at the centre of each panel. A 10m run with 1.83m panels needs 6 panels and 7 posts, not 5 panels and 6 posts. The extra post at the end is easy to miss when ordering.
- Buying exactly the calculated number of panels with no spare. A 5% extra allowance is sensible for damaged panels, future repairs, or if a panel needs trimming to fit around a gate or post.
- Using the wrong postcrete mix for the soil type. Sandy or free-draining soils need a richer mix; heavy clay can be set with less. If you’re unsure, buy a little extra — postcrete is cheap compared to a leaning fence.
- Not checking the panel height includes the gravel board. Most fence panels are quoted by the height of the panel itself, but a 1.8m fence often includes a 150mm gravel board at the base, making the total height 1.95m. Check this against any height restrictions before buying.
What to look for when buying fencing
Panel construction is the biggest factor in how long a fence will last. Pressure-treated timber panels are the standard in the UK — the preservative is forced into the wood under pressure, giving better protection against rot and insect attack than surface-applied treatments. Look for a guarantee of at least 10 years against rot, and check that the posts are also pressure-treated, not just the panels.
Post size matters more than people think. A standard 1.8m fence needs posts of at least 100mm x 100mm (4x4 inch) in section. On exposed or windy sites, or for fences over 1.8m tall, step up to 125mm x 125mm (5x5 inch) posts for extra rigidity. Concrete posts last longer than timber but are harder to replace if damaged; timber posts are easier to work with but will eventually need replacing.
Finally, think about the gravel board. A pressure-treated gravel board sits between the bottom of the panels and the soil, preventing the panel bottom from sitting directly in damp earth where it will rot faster. A 150mm gravel board is standard for domestic fencing. If your garden slopes, you may need a longer board on the lower side or a stepped fence design to keep the bottom of each panel clear of the soil.
More questions answered
Do I need my neighbour's permission to replace a shared fence?
You don't normally need permission to replace a fence on your own side of a boundary, but if the fence or its posts sit directly on the boundary line or are jointly owned, it's good practice — and can avoid disputes — to discuss the work with your neighbour first, especially if you need temporary access to their side to fit posts or panels.
How deep should fence posts be?
As a general rule, bury around a third of the total post length in the ground, with a minimum hole depth of about 600mm (60cm) for a standard 1.8m panel fence. Deeper holes, around 750mm, are safer on exposed or windy sites to stop posts leaning over time.
Concrete or postcrete for fence posts?
Postcrete (fast-setting fence post concrete) is the easier option for most DIY jobs — you pour it dry around the post with some water and it sets rigid in minutes, holding the post in position while you work. Traditional mixed concrete is cheaper for large jobs but needs mixing, more care to keep posts aligned, and longer to cure.
How many bags of postcrete does one fence post need?
For a standard post hole of around 300mm x 300mm x 600mm, two 20kg bags of postcrete is a reasonable estimate for most residential fence posts, though larger or deeper holes for taller fences may need three.
Can I reuse existing fence posts?
If the existing posts are sound, level and the right size for your new panels, reusing them can save money. However, if they’re rotten, leaning or the wrong height, it’s false economy to try to make new panels fit around them — bad posts are the most common cause of a new fence going out of alignment within a year or two.
What is the maximum fence height allowed in the UK?
For most residential properties, the maximum height without planning permission is 2m for a rear boundary fence and 1m for a front boundary fence (or 1.5m if you have a gate, wall or other feature that already exceeds 1m). If you need a taller fence — for example to screen a noisy road or a higher neighbouring property — check with your local planning authority first.
Should I use concrete or timber fence posts?
Concrete posts last longer and don’t rot, but they’re heavier to handle, harder to cut to length on site, and almost impossible to replace if damaged. Timber posts are easier to work with, can be cut to exact length, and are simpler to replace, but they will eventually need treating or replacing. For most domestic fences, pressure-treated timber posts offer the best balance of cost, ease of installation and longevity.
How much clearance should I leave at the bottom of the fence?
Leave a 75–100mm gap between the bottom of the fence panel and the soil to prevent rot and allow air circulation. A gravel board is the standard way to achieve this — it sits on the ground and the panel sits on top of it, keeping the timber clear of direct soil contact. On a sloping site, stepped panels may leave a larger gap on the lower side, which is fine as long as the panel isn’t touching the soil anywhere.