We think this tool will be helpful to personnel of all skill levels to quickly perform calculations and eliminate many unsuitable choices. The final decision on wire and circuit protection should come after a review based on additional sources, such as the ABYC standards or one of the many books in the field.


All marine electrical systems present a risk of fire and other hazards. Blue Sea Systems makes no representation or warranty that this calculator will be suitable to address your particular situation or requirements.

Blue Sea Systems has developed this calculator for use only by individuals having the appropriate working knowledge and understanding of marine electrical systems. This calculator is based in part on the ABYC’s tables and standards contained in E-11 “AC and DC Electrical Systems on Boats,” but it is not intended to be a substitute for calculations based directly on these or other industry standards that may apply. This tool is a prototype, and may contain errors of entry or calculation.

This calculator does not account for all possible variables and factors relevant to the selection of wire size and circuit protection. Such variables may include overloads (such as changing the size of light bulbs or adding additional loads to circuits), wiring errors (such as loose connections or poor crimps), heated terminations (such as motor terminals, heating appliances, or lighting fixtures), data input errors, unusual environmental heat sources, and inadequate or defective wire insulation, software defects, and/or malfunctions of a browser or server computer.

This calculator is not a substitute for the expertise of a marine electrical professional. Under no circumstances should this calculator be used as the sole basis for selecting wire size or circuit protection. Any wire size or circuit protection tentatively selected with this tool should be reviewed for adequacy, before installation, by a professional applying the applicable industry standards.

Blue Sea Systems expressly disclaims responsibility for any use of this calculator that results in inadequate wire size or circuit protection.

To use this tool, you must accept the terms of this disclaimer.

I accept the terms of this disclaimer.

Find the Correct DC Wire

Information required to meet ABYC Standards

(V DC)


Modify these default values if necessary


Additional Derating Factors (if applicable)

Find the Correct Circuit Protection


©2006-2024 Blue Sea Systems. All rights reserved. Portions based on ABYC Standards.