A sheep field fence should keep the mesh opening at about 100 mm (10 cm) or tighter in the lower section. Wider wire lets a sheep or lamb push its head between the wires, and once the shoulders stop the head the animal is caught by the head or horns rather than being held out. Government guidance notes that wire spaced about 150–200 mm can trap horns or heads so that an animal “fights the fence”, risking cuts to the head and neck (USDA-NRCS Range Technical Note 102). The practical build is a graduated mesh — tight at the ground, wider at the top.
At a glance
- The number: aim for 75–100 mm in the lower section; treat 100 mm as a practical upper limit, not a standard value.
- The danger zone: roughly 150–200 mm wire spacing — wide enough for a head or horn to pass, narrow enough to trap it (USDA-NRCS).
- Lambs set the spec: Teagasc uses 75 × 75 × 4 mm weld mesh to hold lambs.
- Graduated beats uniform: coarse at the top, tight at the bottom, where sheep actually push.
- Height is a separate decision: sheep mesh normally runs 0.80–0.90 m, up to 1.2 m with a top wire, and 1.45 m where the fence must also hold off wildlife.
Why is about 10 cm the practical limit for sheep mesh?
Sheep do not fail a fence by jumping it. They push, rub and work along it, and the failure mode that matters is a head pushed between wires. USDA-NRCS describes exactly that: with wire spaced roughly 6–8 in (152–203 mm) apart, an animal can “pass horns or antlers through the fence” and become entangled between the wires, then fight the fence, “risking cuts to the head and neck and potentially death”. The same note is explicit that closer spacing is needed to hold domestic sheep than for a fence designed to let wildlife through, and it lists a 254 mm (10 in) bottom-wire height when domestic sheep are held.
So 10 cm is not a rule written into a standard. It is the opening size at which a sheep stops being held out and starts being caught. Everything below about 100 mm is safer; everything above it is a risk that grows with the animal’s horns and the pressure on the fence line.
What mesh size holds lambs, and what holds adult sheep?
- Lambs: the tightest mesh you can justify. Teagasc’s sheep handling guide uses 75 × 75 × 4 mm weld mesh to hold lambs.
- Adult sheep: a graduated stock fence with the bottom section around 75–100 mm.
- 150 mm and coarser: cattle, large mature stock, or a fence that has to let wildlife pass — a different job, and not a sheep specification.
The same guide warns that horns and ear tags can get caught in mesh, so the tightest opening belongs exactly where sheep crowd a fence: gateways, troughs, shade lines and corners, not just on the long straight runs.
Why does graduated mesh beat one uniform opening?
Graduated mesh is coarse at the top and progressively tighter towards the ground. That matches how sheep use a fence: the pressure, the rubbing and the lamb-sized heads are all in the bottom third, while the top of the fence mainly has to stay visible and hold tension. It is also the design the wider literature associates with sheep exclusion: the multi-species review in Sustainability 17 (2025) 7295 lists graduated mesh and a skirt for the sheep and wetland exclusion design, while the cattle exclusion design at 115 cm needs neither.
Practical consequence: when you compare two fences that are both “sheep netting”, the one with the tighter bottom aperture is doing the work. Ask for the bottom opening, not just the average mesh.
Do horned sheep and rams change the answer?
Yes, and this is where an otherwise reasonable fence gets dangerous. A horn is wider than the skull, so an opening that lets the head through can still trap the horn on the way back. Supplier selection guides put “do you have goats with horns that can get stuck in the fence?” among the first questions asked when choosing mesh, and Teagasc repeats the warning for horns and tags. For horned breeds, take the tightest lower mesh available and avoid wide openings at head height, whatever the fence does on the rest of the line.
How do you read mesh size off a field fence label?
A stock fence label reads in four parts. 7/90/30 400m means 7 horizontal (line) wires, a fence 90 cm high, vertical picket wires spaced 30 cm apart, supplied in a 400 m roll. The third number is the picket spacing in centimetres — 30 means 30 cm, not 30 mm — and it is not the same thing as the aperture. The aperture is set by the line-wire spacing, which on a graduated fence is tightest near the ground.
- Ask for both: picket spacing and the bottom opening in mm.
- Also pin down the knot type (fixed knot, hinge joint or ring lock), the coating, the line wire diameter (commonly 2.50 mm, with 2.80 mm top and bottom wires on heavier builds) and the roll weight.
- Roll length: 100 m is the most common stock fence roll size in Australia and New Zealand; we also weave 200 m and 400 m rolls to order.
How high should the fence be, and what about the gap at the ground?
- 0.80–0.90 m of sheep mesh is the usual starting height, with electric or barbed wire added at the bottom where pressure is high (NSDA livestock fencing guidelines).
- 90 cm mesh plus a top wire to 120 cm is the typical Australian stock fence build for sheep.
- 1.0 m internal and 1.2 m external fencing for a sheep handling unit (Teagasc), and 1.45 m where the fence must also hold off wildlife in a wetland setting (Sustainability 17 (2025) 7295).
- Close the gap underneath. The exclusion designs that hold sheep use a skirt; if you run goats in the same paddock, the gap under the wires should be no more than 80 mm and external diagonal braces should be avoided because goats use them as a ladder.
- Posts: netting is typically posted at about 3 m centres; plain-wire runs can go to 10 m between posts provided droppers hold the wire spacing between them.
Height and mesh size are separate decisions and it is worth reading them together: see our guide to fence height for sheep and cattle for the height boundaries.
Sheep mesh size: quick comparison
| Job | Opening that works | Where the number comes from |
|---|---|---|
| Lambs | About 75 × 75 mm | Teagasc sheep handling guide (75 × 75 × 4 mm weld mesh) |
| Adult sheep, lower section | About 75–100 mm | USDA-NRCS: closer spacing needed to hold domestic sheep |
| Danger zone | About 150–200 mm | USDA-NRCS Range Technical Note 102 (heads and horns trapped) |
| Wildlife passage | 254–381 mm with a 254 mm bottom wire | USDA-NRCS Range Technical Note 102 |
| Cattle / large stock | Coarser mesh, no graded bottom | Sustainability 17 (2025) 7295, Table 1 |
None of these is a fixed catalogue number. They are starting points for a specification that also has to carry your rainfall, terrain, stocking pressure and local standard. As a factory we weave to your numbers: send the stock, the terrain and the standard you buy against, and we will quote the mesh and the coating to match. For the wider picture on knot types and animal-by-animal builds, see best fencing for cattle, sheep and deer and the field fence specifications.
Frequently asked questions
Tell us your breed and your ground, and we will spec the mesh.
Send the breed (horned or not), the age of the youngest lambs, your terrain and your local standard, and we will recommend the bottom aperture, picket spacing and coating — or browse the full field fence specifications first.
