Essential Shipyard University

ESI Wire Calculator (ABYC)

Size a marine conductor the right way — by current (ampacity) AND by run length (voltage drop), per ABYC E-11-2025. Enter the load, the one-way run and the conditions; it returns the AWG you need.

E-11ABYC

3% / 10%Voltage drop

105°CMarine wire

Load current (amps)

Run length — one way (feet)

System voltage

Circuit type (allowable drop)

Location (temperature)

Conductors bundled together

—AWG — recommended (the larger of the two below)

By ampacity (heat)— AWG

By voltage drop (length)— AWG

Based on ABYC E-11-2025: 105°C tinned-copper conductor ampacity (outside-engine-space table) with temperature & bundling derates, and the 3% / 10% voltage-drop limits. Always use marine-grade tinned, finely-stranded wire. Verify against the current ABYC tables for the exact insulation and conditions.

AWG	Ampacity (105°C, outside ER)
18	20 A
16	25 A
14	35 A
12	45 A
10	60 A
8	80 A
6	120 A
4	160 A
2	210 A
1	245 A
1/0	285 A
2/0	330 A
3/0	385 A
4/0	445 A