Calculate Cable Size Fixed Jun 2026

When in doubt, go bigger. But don't guess—calculate.

But don't worry. Calculating the correct cable size is straightforward once you understand the four key factors: calculate cable size

"Great for office work, but double-check your inputs. This is my go-to web calculator when working from my laptop. It breaks the calculation down into layman's terms, explaining why a specific gauge is recommended. It handles the 'Voltage Drop' factor very clearly, which many cheap calculators ignore. When in doubt, go bigger

| Condition | Derating Factor | | :--- | :--- | | Ambient 30-40°C (normal) | 1.00 | | Ambient 40-50°C (hot attic) | 0.87 | | 3-6 cables bundled | 0.80 | | 7-9 cables bundled | 0.70 | When in doubt