Fuse Size & Wire Gauge Calculator
Calculate fuse size, wire gauge (AWG or mm²), voltage drop, and placement for 12V, 24V, and 48V DC systems.
Open CalculatorVoltPlan Tools
Electrical calculators built for 12V systems
Use VoltPlan's free calculators to size wire, fuse protection, battery banks, inverters, and solar arrays for campers, boats, RVs, and off-grid builds.
Battery Bank Sizer
Daily Wh, days of autonomy, and chemistry-aware DoD limits for LiFePO4, AGM, gel, and lead-acid banks at 12V, 24V, or 48V.
Open CalculatorInverter Size Calculator
Continuous wattage, startup surge, and DC current for camper, boat, and off-grid AC loads. Pure-sine recommendation included.
Open CalculatorSolar Panel Calculator
Array wattage, panel count, and MPPT charge controller current sized for your daily Wh and sun region.
Open CalculatorVoltage Drop Calculator
Pick a wire gauge and length, see voltage drop in volts and percent. AWG and mm² with temperature derating for any 12V/24V/48V circuit.
Open CalculatorWatts to Amps Converter
Convert between watts and amps at any DC or AC voltage. Optional power factor for motor and inverter loads.
Open CalculatorAh to Wh Converter
Convert battery capacity (Ah) to stored energy (Wh and kWh) at 12V, 24V, or 48V. Reference table for common battery sizes included.
Open CalculatorBattery Runtime Calculator
How long will your battery run a given load before hitting the chemistry-aware DoD limit. LiFePO4, AGM, Gel, lead-acid.
Open CalculatorBattery Charge Time Calculator
Estimate time to charge a battery from an AC charger, DC-DC, or solar array. Bulk plus chemistry-aware absorption phase.
Open CalculatorLearn the reasoning behind the numbers
The calculators are faster when you already understand the tradeoffs. These guides cover fuse placement, marine wiring layouts, solar sizing, and cable selection in more depth.