Off-Grid Load Calculator
Calculate your total energy needs for an off-grid system. Add devices by room, set usage hours, and determine your daily, weekly, and monthly power consumption including ghost loads and inverter overhead.
Before sizing batteries or solar panels for an off-grid system, you need to know exactly how much energy you'll use each day. This off-grid load calculator lets you build a device-by-device energy budget organized by room. It accounts for ghost loads (standby power draw), inverter overhead losses, and gives you totals in Wh/day, Wh/week, and kWh/month — the numbers you need for accurate battery and panel sizing.
Start with a room preset below, then customize wattages and hours for your specific appliances. Once you have your daily Wh total, use our battery sizing calculator and solar array sizing calculator to complete your system design.
Add Devices
Select a room and device to add with standard wattage values, or add a custom device.
System Overhead
Ghost loads and inverter self-consumption add to your total. Adjust these defaults as needed.
Standby power consumed by devices when off. Typically 5-10% of total load.
Power the inverter uses to run itself, even with no load attached.
Results
Add devices and click calculate to see your energy requirements
How to Use This Calculator
1. Add Your Devices
Select a room from the dropdown to see common devices with standard wattage values pre-filled. You can also add custom devices with your own wattage values. Use a kill-a-watt meter for the most accurate readings.
2. Set Hours & Quantity
Adjust the hours per day each device runs and the quantity if you have multiples. For intermittent loads like a well pump, estimate the total runtime per day (e.g., 2 hours total).
3. Mark Simultaneous Use
Check the "simultaneous" box for devices that run at the same time. This determines your baseline power draw, which your inverter must handle continuously. This is critical for sizing your inverter.
4. Review Overhead
Ghost loads (5% default) account for phantom power draw from devices in standby. Inverter self-consumption (100W, 24h default) covers the inverter's own power needs. Adjust both values based on your specific equipment.
Need help designing your off-grid system?
Our team can review your load requirements and recommend the right equipment.