Free Solar & Energy Calculators
Size solar systems, batteries and inverters, and check your solar payback in seconds.
18 free solar & energy, no sign-up, no watermarks.
Solar Panel Calculator
Work out how many solar panels and what system size you need.
Available nowBattery Backup Calculator
Size an inverter/UPS battery bank and estimate backup time.
Available nowBattery Pack Calculator
Design a series/parallel cell pack: voltage, mAh, Wh, weight and runtime.
Available nowSolar Payback Calculator
Estimate solar payback period, lifetime savings and ROI.
Available nowInverter Size Calculator
Find the inverter VA/kVA size your appliance load needs.
Available nowSolar Battery Bank Calculator
Size an off-grid solar battery bank in kWh, Ah and batteries.
Available nowSolar Output Calculator
Estimate daily, monthly and yearly solar energy production.
Available nowAC Size Calculator
Find the AC tonnage and BTU your room needs.
Available nowEV Charging Calculator
Estimate EV charging time and cost from any charge level.
Available nowGenerator Size Calculator
Work out the kVA generator size your load needs.
Available nowAppliance Energy Calculator
Turn an appliance wattage into daily, monthly and yearly running cost.
Available nowTransformer Winding Calculator
Design a step-up or step-down transformer: turns, wire gauge (SWG) and core size for inverters, UPS and voltage conversion.
Available nowVoltage Stabilizer (AVR) Calculator
Design a buck-boost stabilizer: transformer VA, wire gauge and a full relay tap table for any input voltage range.
Available nowBuck Boost Converter Calculator
Step-up or step-down DC-DC: output current, input current, power, heat loss and duty cycle.
Available nowBattery Charging Calculator
Safe charge voltage, charge current, charge time and usable capacity for any battery pack.
Available nowWatts to Amps Calculator
Convert watts to amps for DC and AC, with power factor.
Available nowAmps to Watts Calculator
Convert amps to watts for DC and AC, with power factor.
Available nowkVA to kW Calculator
Convert between kVA and kW using power factor.
Available now