Home energy should be easy to understand
Our vision is a world where every household can understand its energy use and costs, using clear numbers instead of guesswork.
We build free, accurate tools and write practical guides that explain how electricity works at home, what appliances really use and how to make informed decisions.
Home Energy Calculators & Tools
Each calculator has its own page with the formula, a worked example and its limits explained.
Electricity Cost Calculator
Estimate what a device or your home costs to run per hour, day, month and year at your own electricity rate.
Go to the electricity cost calculator →Appliance Energy Usage Calculator
Estimate the kWh and running cost of fridges, air conditioners, heaters, ovens and other appliances.
Go to the appliance energy calculator →Electrical Unit Converter
Convert watts to amps, amps to watts, volts to watts and watts to kWh.
Go to the electrical unit converter →Home Energy Audit
Estimate how much standby (phantom) power adds to your yearly electricity use.
Go to the home energy audit tool →Home Energy Articles & Guides
Direct answer first, detail after. Every guide links to the tool that does the maths for you.
How Many Watts Does a Fridge Use?
Typical running watts, daily kWh and what changes them.
Calculate appliance usage →Watts vs Kilowatt-Hours Explained
The difference between power and energy, and how your bill uses it.
Read breakdown & formula →How to Calculate Amps
Amps from watts and volts, with worked examples.
Use unit converter →Does Unplugging Appliances Save Electricity?
What standby power is and when unplugging is worth it.
Check phantom load tool →Energy-Efficient LED Bulbs
How LED wattage and lumens compare with older bulbs.
Compare bulb savings →Gas vs Electric Water Heater
How running costs and efficiency compare.
Estimate heating cost →Key home energy terms, defined
Clear, concise reference definitions for the core electrical terms used across household bills and appliance labels.
Watt (W)
A unit of power. It measures how fast a device uses energy at a given moment. One watt is one joule per second.
Kilowatt (kW)
1,000 watts. Larger appliances such as heaters are often rated in kilowatts.
Kilowatt-hour (kWh)
A unit of energy. It equals using 1 kilowatt of power for 1 hour. Electricity bills are based on the kWh you use.
Volt (V)
A unit of electrical potential difference, the "push" that drives current through a circuit.
Ampere (amp, A)
A unit of electric current, the rate at which electric charge flows.
Appliance running cost
The estimated cost of operating an appliance: kilowatts × hours used × price per kWh.
Standby (phantom) power
Electricity a device draws while switched off or idle, such as chargers and TVs on standby.
Electricity rate
The price you pay per kWh. It varies by country, provider and tariff, so check your own bill.
How do you calculate electricity cost?
Divide the appliance's watts by 1,000, multiply by the hours used, then multiply by your price per kWh. The result is an estimate, because real use and tariffs vary.
- Find the appliance's power in watts (label or manual).
- Divide by 1,000 to get kilowatts.
- Multiply by the hours it runs to get kWh.
- Multiply kWh by your electricity rate.
Worked example (rate is an example, not a quote): A 1,500 W heater is 1.5 kW. Used for 3 hours, it uses 4.5 kWh. At $0.15 per kWh, that is about $0.68.
Formula Breakdown
Cost = kWh × Electricity Rate ($/kWh)
Browse Home Energy Topics
Explore our categorized knowledge hubs covering billing, consumption, appliance analysis, and efficiency techniques.
Frequently asked questions
Clear, concise answers to common questions about household electricity and energy estimations.
What is Homgy?
Homgy is an independent website offering free home energy calculators and guides. It is not a utility or energy supplier.
What is the difference between watts and kilowatt-hours?
Watts measure power at a moment. A kilowatt-hour measures energy used over time (1,000 watts for one hour), and it is what your bill charges for.
How do I find out how much electricity an appliance uses?
Find its wattage on the label or manual, estimate the hours it runs, and use the appliance energy usage calculator. A plug-in energy meter gives the most accurate reading.
How do I convert watts to amps?
For a simple circuit, amps equal watts divided by volts. Use the electrical unit converter to check your numbers.
Does unplugging appliances save electricity?
Yes, a little. Devices on standby still draw power, though the saving per device is usually small. See the full guide for details.
Are the calculator results exact?
No. They are estimates that depend on the values you enter. Actual bills vary with tariffs, usage and appliance condition.
Understand your home's energy use
Start with a calculator, or learn the basics first.