Electrical Calculators
From home energy bills to solar savings and EV charging times — our free electrical calculators handle the numbers so you don't have to.
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Home Energy
Calculate solar savings, electricity costs, and EV charging times
Circuit Basics
Ohm's Law, watts, voltage, and resistors
Electrical Glossary — Key Terms Explained
- Watt (W)
- The unit of electrical power. Power = Voltage × Current (P = VI).
- Ampere (A)
- The unit of electrical current — the rate at which charge flows through a circuit.
- Volt (V)
- The unit of electrical potential difference (voltage) — the force that drives current through a circuit.
- Ohm (Ω)
- The unit of electrical resistance. Defined by Ohm's Law: R = V/I.
- kWh
- Kilowatt-hour — the standard unit for measuring electricity consumption. 1 kWh = using 1,000 watts for 1 hour.
Frequently Asked Questions
How do I calculate my electricity bill?
Multiply the wattage of each appliance by the hours used per day, divide by 1,000 to get kWh, then multiply by your unit rate (p/kWh or ¢/kWh). Our Electricity Cost Calculator does this automatically.
How many solar panels do I need for my home?
A typical UK home uses 3,100 kWh per year and needs 6–10 panels. A US home averages 10,500 kWh and needs 20–25 panels. The exact number depends on panel wattage, roof orientation, and your local sun hours.
How long does it take to charge an EV?
It depends on the charger type and battery size. A 7kW home charger adds roughly 30–40 miles per hour. A 22kW charger triples that. A 150kW rapid charger can add 100 miles in 20 minutes.
What is Ohm's Law?
Ohm's Law states that Voltage (V) = Current (I) × Resistance (R). It describes the relationship between three fundamental electrical quantities and is the foundation of circuit analysis.