About VoltBudget

VoltBudget makes free, plain-language calculators for people building their own power systems in camper vans, sailboats, RVs and off-grid cabins.

Every calculator shows its formula and assumptions, so you can check the math yourself. The numbers follow common industry practice: conservative usable capacity for batteries, real-world losses for solar, headroom for inverters, and voltage-drop limits widely used for low-voltage DC wiring.

These tools are for planning. A mistake in a high-current DC system can cause a fire, so have a qualified electrician or marine electrical technician review your installation.

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