How this calculator works
Enter total fence length (or rectangle L×W), select fence type, number of hot strands, and vegetation load. We compute effective wire distance, then multiply by conservative joules-per-mile (or per km) and fence-type factors to recommend output joules. We also show a marketing-style “range” (mi/km) for comparison.
Rounding: distances to 2 decimals; joules to 2 decimals.
Rules of thumb & formulas
- Effective wire miles = physical miles × hot strands (mesh counts as 1)
- Base output joules per mile:
- Low vegetation: 0.6 J/mi (≈0.373 J/km)
- Medium vegetation: 1.0 J/mi (≈0.621 J/km)
- High vegetation: 2.0 J/mi (≈1.243 J/km)
- Fence type factor:
- High-tensile smooth: ×1.0
- Barbed: ×1.1
- Woven/mesh: ×1.2
- Recommended output J = effective miles × base J/mi × type factor; minimum 1.0 J
- Good / Robust band = ±25% of recommendation
- Suggested marketing “range” (clean single wire) ≈ J ÷ 0.6 (mi) or J ÷ 0.373 (km)
Worked example
Rectangle 660×330 , high-tensile, 5 hot strands, medium vegetation:
- Perimeter = 2×(660+330) = 1,980 = 0.375
- Effective wire distance = 0.375 × 5 = 1.875
- Base J/mi (medium) = 1.0; type factor = 1.0 → J = 1.875 × 1.0 × 1.0 = 1.88 J (≥ 1.0 J min)
- Good/Robust ≈ 1.41–2.34 J; marketing “range” ≈ 1.88 ÷ 0.6 = 3.13
Assumptions & notes
- These are planning estimates. Real performance depends on grounding, insulators, joints, and actual vegetation.
- Predators/long runs: size toward the robust end.
- Solar units: derate for winter/cloud or increase panel/battery size.
- Mesh/woven counted as one effective hot conductor for sizing convenience.
Prepared by AgCalculator · Last updated October 27, 2025
FAQ
What’s the difference between stored and output joules?
Stored joules are inside the unit; output joules are delivered to the fence. We size using output joules for clarity.
Are “miles of fence” ratings accurate?
They’re optimistic for clean single-wire setups. Real-world vegetation, multiple strands, and grounding reduce range — size with margin.
How important is grounding?
Critical. Use multiple long ground rods in moist soil, spaced and bonded properly.
Do you support metric?
Yes — use the toggle at the top. The math normalizes to US length units and converts for display.