Tools for the rig and the boat.
The calculators and checkers we reach for when we're sizing a house bank, a solar array, or the wire to carry it, whether that's in a van, an RV, or on a boat. Free, no sign-up, and built on the same research as our guides.
Sea
Boat Safety Gear Requirements Checker
Enter your boat's length and a few details, and see the gear the US Coast Guard generally requires you to carry, plus the gotchas owners trip on.
Open the checker → CalculatorSailboat Battery Bank & Solar Calculator
Turn your onboard loads into the house-bank size, solar array, and charge-controller numbers you actually need.
Open the calculator → CalculatorAnchor Size & Scope Calculator
Size the anchor for your boat, then get the scope and rode to deploy for the conditions you're anchoring in.
Open the calculator → CalculatorBoat Fender & Dock-Line Size Calculator
One boat length gives you the fender diameter and count, plus the dock-line diameter and the length to cut your bow, stern, and spring lines.
Open the calculator → CalculatorMarine DC Wire-Gauge Calculator
Enter your load, run length, and voltage for the AWG that satisfies both voltage drop and ampacity, the ABYC way, plus the fuse to match.
Open the calculator →Road
RV Solar & Battery Calculator
List your rig's 12V loads and this tool sizes the house battery bank, solar array, charge controller, and inverter an off-grid RV or van actually needs.
Open the calculator → CalculatorRV Battery Runtime Calculator
Enter your battery bank and the 12V loads you run, and see how long it lasts: days at your daily draw, the fridge-only figure, and hours at a heavy load (with the lead-acid Peukert penalty).
Open the calculator → CalculatorPropane Tank Runtime Calculator
Pick your tank size and the propane appliances you run, and see how long it lasts: days of runtime, the furnace-only figure, and your daily BTU burn, with the cold-weather and CO cautions.
Open the calculator → CalculatorRV & 12V DC Wire-Gauge Calculator
Enter your load, run length, and voltage for the AWG that satisfies both voltage drop and ampacity, the NEC way for RV, van, and off-grid 12V DC, plus the fuse to match.
Open the calculator →