Jobsite Power Calculator for Contractors
Jobsite power calculator for contractors, agricultural operators, and off-grid professionals. Select your tools, set quantities, and get your minimum power station capacity, inverter output, and surge rating in seconds — no guesswork.
How to Use This Calculator
Start with the Load Calculator tab. Select your industry, then tap each tool you’ll be running simultaneously — not sequentially. The calculator uses your running wattage and surge ratings to output your minimum continuous inverter spec and recommended battery capacity sized for a 6-hour workday..
Move to the Runtime Estimator to verify your chosen power station will last a full shift. Enter the unit’s Wh capacity, select its inverter efficiency tier, and set your expected load draw. The depth-of-discharge slider lets you model conservative vs. aggressive use.
Use the Solar Recharge Calculator last. Input your battery size, starting state of charge, available peak sun hours for your region, and panel wattage. The result tells you exactly how many panels you need and whether you can fully recharge within a single shift. Peak sun hours vary significantly by region — use local solar irradiance data for the most accurate recharge estimates.
According to the U.S. Department of Energy, peak sun hours vary significantly by region — use local solar irradiance data for the most accurate recharge estimates.
Frequently Asked Questions
How does this jobsite power calculator work?
Select the tools you plan to run simultaneously from the load calculator, set quantities, and click Calculate. The tool adds up running wattage, identifies peak surge draw, and outputs your minimum battery capacity and inverter rating based on a standard 6-hour workday.
What is the difference between running watts and surge watts?
Running watts is the continuous power a tool draws while operating. Surge watts is the brief spike at startup — typically 2–3× the running draw for motors and compressors. Your power station’s inverter must handle both: continuous output for running load and peak output for surge.
How many solar panels do I need to recharge a portable power station in one day?
Use the Solar Recharge Calculator above. As a general rule, divide the Wh you need to replace by your peak sun hours, then divide by panel wattage and multiply by 1.18 to account for efficiency losses. A 2,000Wh battery depleted to 20% needs 1,600Wh replaced — roughly 3–4 × 200W panels over 5 peak sun hours.
What size power station do I need for a construction site?
For light duty (lighting, chargers, one tool at a time) a 1,000–1,500Wh unit works. Mid-duty crews running saws and drills simultaneously need 2,000–3,000Wh with 2,000W+ continuous output. Heavy-duty setups with compressors or welders require 3,000Wh+ and a robust surge rating — use the load calculator above to get your exact spec.