Energy & environment calculators
Energy and cost estimates from the ratings and tariffs you enter, with the assumptions behind every figure stated.
Batteries
- Battery Backup Runtime CalculatorEstimate how long a battery, UPS or inverter backup will run a load from its Ah and voltage or kWh, usable depth of discharge and inverter efficiency.
- Battery State of Charge CalculatorTrack a battery’s state of charge by coulomb counting: starting SoC, current and time give the new SoC, remaining Ah and the time to full or empty.
Bioenergy
Electrical engineering
- Inverter Efficiency CalculatorCalculate an inverter’s conversion efficiency from its DC input and AC output power, the watts lost as heat and the energy lost over a year of operation.
- Cable I²R Loss CalculatorCalculate the resistive power loss, voltage drop and yearly energy cost of a copper or aluminium cable from current, length and cross-section.
- Power Transformer Efficiency CalculatorCalculate a power transformer’s efficiency at any load and power factor from its kVA rating, no-load core loss and full-load copper loss.
Electrical power
- Power Factor Correction CalculatorFind the capacitor kVAR and µF needed to raise power factor to a target, with the drop in kVA and line current, for single- or three-phase supplies.
- Three-Phase Power CalculatorConvert between three-phase current and power: kW, kVA and kVAR from line voltage, current and power factor, or the current a given kW load draws.
Electricity & appliances
- Appliance Standby Energy CalculatorWork out how many kWh and how much money devices left on standby use in a year from their standby watts, the hours on standby and your tariff.
- AC Annual Running Cost CalculatorEstimate an air conditioner’s yearly electricity use and cost from its power draw, or from cooling capacity and EER, plus hours, days and tariff.
Electricity bills
- Home Electricity Bill CalculatorEstimate a home electricity bill from kWh used with up to three tariff blocks, a fixed or standing charge and tax, using the rates on your own bill.
- Commercial Demand Charge CalculatorWork out a business electricity bill with demand charges: billed kW including any ratchet, energy charge, load factor and true cost per kWh.
Electric vehicles
- EV Charging Time CalculatorEstimate how long an electric car takes to charge from its battery size, start and target charge, charger power, the car’s own limit and charging losses.
- EV Charging Cost CalculatorWork out what it costs to charge an electric car at your electricity price, including charging losses and session fees, plus the cost per 100 km.
- EV Battery Range CalculatorEstimate an electric car’s remaining range from usable battery size, current charge, a reserve and its real consumption in kWh/100 km, Wh/km, Wh/mi or mi/kWh.
- EV vs Petrol Running Cost CalculatorCompare a year’s energy and maintenance cost of an electric car and a petrol car from your mileage, consumption and local electricity and fuel prices.
Emissions
- Carbon Emissions CalculatorEstimate CO₂-equivalent emissions from electricity, petrol, diesel and natural gas use, multiplying each by an emission factor you enter from an official source.
- Refrigerant GWP CalculatorConvert a refrigerant charge in kg to tonnes of CO₂-equivalent using its global warming potential, with the yearly impact of a leak rate you enter.
Emissions & waste
- Waste Diversion Rate CalculatorCalculate the waste diversion rate: recycled, composted and reused waste as a share of all waste generated, with a choice on energy recovery.
- Recycling Carbon Savings CalculatorEstimate the greenhouse-gas emissions avoided by recycling aluminium, paper, plastics and glass, using the per-kg emission factors you choose.
- Electricity Emissions Intensity CalculatorWork out the carbon intensity of an electricity mix in g CO₂e/kWh and lb/MWh from each source’s generation and emission factor, and your own footprint.
- Tree Planting Carbon Estimate CalculatorEstimate the CO₂ a planting absorbs from the number of trees, survival rate, an average uptake per tree and years, and how many trees offset a yearly amount.
Generators & wind
- Diesel Generator Fuel CalculatorEstimate a diesel generator’s fuel use and cost from its kW rating, load and the datasheet consumption, plus cost per kWh and hours per tank.
- Wind Turbine Power CalculatorEstimate wind turbine power from rotor diameter, wind speed, air density and power coefficient, with the wind’s total power and the Betz limit.
Heating & insulation
- Heat Pump Payback CalculatorCompare the yearly cost of heating with your current boiler and with a heat pump, using SCOP and your fuel and electricity prices, and see the payback period.
- Home Insulation Savings CalculatorEstimate the heating energy and money insulation saves from the area, U-values before and after, heating degree days, boiler efficiency and fuel price.
Heating & lighting
- Heat Pump COP CalculatorWork out a heat pump’s coefficient of performance from heat output and electrical input, compare it with the Carnot limit and estimate yearly running cost.
- LED Retrofit Savings CalculatorWork out the yearly kWh and money saved by replacing lamps with LEDs, from wattages, hours of use and your electricity price, with payback in months.
Resilience
Solar
- Solar PV System Sizing CalculatorSize a solar PV system from your electricity use, local peak sun hours and system losses: kWp needed, number of panels, roof area and yearly output.
- Solar Payback CalculatorFind how many years solar panels take to pay for themselves, with tariff rises, panel degradation and running costs, plus lifetime net savings.
- Solar Self-Consumption CalculatorFrom solar generation, export and household use, work out the self-consumption rate, self-sufficiency, grid imports and what your solar is worth.
- Solar Inverter Sizing CalculatorSize a solar inverter from array kWp and a DC/AC ratio, and check the maximum panels per string from cold-weather Voc and the inverter voltage limit.
Solar & storage
- Solar Panel Tilt Angle CalculatorFind a fixed solar panel tilt for your latitude, the seasonal summer and winter angles, and the tilt that faces the noon sun squarely in any month.
- Grid Export Revenue CalculatorEstimate yearly income from solar power exported to the grid at your export tariff, plus the value of the solar you use yourself at your import rate.
- Net Metering Estimate CalculatorEstimate an electricity bill under net metering: consumption minus solar generation at your import rate, with any excess credited at your credit rate.
- Solar Battery Storage Days CalculatorWork out how many days a solar battery bank can run your daily load without sun, and the nominal capacity needed for a target number of days of autonomy.
Water
- Household Water Consumption CalculatorEstimate your home’s daily and yearly water use from showers, toilets, taps, laundry, dishwasher and garden, per person and as a yearly bill.
- Rainwater Collection CalculatorEstimate how much rainwater a roof can collect from its area, the rainfall and a runoff coefficient, in litres, m³ and US gallons, plus days of supply.