Off-Grid Solar & Battery Sizing
Size your DIY system with a free, vendor-neutral calculator. Daily loads, battery bank, solar array, and 2026 AU rebate estimate.
Free to use • No registration • Vendor-neutral
Popular calculators
Quick tools for wiring, batteries, costs, and solar—plus our full off-grid system calculator.
Watts to Amps Calculator
Convert watts to amps for AC or DC circuits with optional power factor.
Amps to Watts Calculator
Convert amps to watts at your system voltage.
Ohm's Law Calculator
Solve for voltage, current, resistance, or power when you know two values.
Appliance Running Cost Calculator
Estimate daily, monthly, and yearly electricity cost for any appliance.
Electricity Bill Calculator
Estimate your bill from kWh usage with tiered rates and fixed charges.
Battery Runtime Calculator
How long will your battery run a given load?
Why WattSizing?
Trusted for accurate, DIY off-grid solar and battery sizing
Accurate System Sizing
Daily load calculator, peak sun hours, and battery bank sizing at 12V, 24V, and 48V.
Vendor-Neutral
Lithium (LiFePO4) and Sodium-ion options with 90% DoD. No brand lock-in.
2026-Ready
Australia STC rebate estimate with factor 6.8 and tapering for May–Dec 2026.
Solar & Energy Tips
Insights on off-grid solar, battery storage, and DIY system design
