Energy Consumption Calculator
Find how much electricity your appliances use in kWh and what it costs, daily, monthly and yearly.
What this tool does
An energy consumption calculator works out how much electricity an appliance or a group of appliances uses over time. Enter the wattage of each appliance, how many you have, and how many hours per day each runs. The calculator converts watts to kilowatts, multiplies by hours to get kilowatt-hours per day, then scales to monthly and yearly totals. Enter your electricity price to see the cost alongside the energy.
Calculates daily, monthly and yearly energy consumption in kWh from wattage, quantity and operating hours.
Supports multiple appliances at once, so a whole household can be totalled.
Shows both energy (kWh) and cost side by side, with a per-appliance breakdown.
Recalculates instantly as you change wattage, hours or appliance count.
How to use it
- Enter the wattage of the appliance (check the label or manual).
- Enter how many of that appliance you have.
- Enter how many hours per day each one runs.
- Repeat for additional appliances.
- Enter your electricity price per kWh to see the cost.
- Read the daily, monthly and yearly kWh and cost.
Why use this calculator
Shows both energy (kWh) and cost side by side, with a per-appliance breakdown, because knowing which appliance uses the most energy is the first step to reducing a bill. Many people suspect the fridge or the heater is the biggest user, but the answer is often surprising. By listing every appliance with its hours and wattage, this calculator turns a vague guess into a ranked list of energy users.
Why we built it
We built the energy consumption calculator to handle multiple appliances in one place, because a single-appliance tool gives a single number but a home has dozens. The electricity bill calculator takes the total and turns it into a bill, and the electricity cost calculator focuses on one appliance's running cost in detail.
If your task goes further, try the kWh to watts converter to work backwards from a bill to an appliance's wattage, and the Appliance Cost Calculator for a simpler single-appliance view.
Who this tool is for
- Homeowners wanting to find the biggest energy users
- Anyone checking whether an old appliance is worth replacing
- Students learning about energy and power
- Landlords and tenants working out who pays for what
When to use it
- Finding which appliances to target for energy savings.
- Checking whether a new energy-efficient appliance will pay for itself.
- Estimating the solar or battery size needed to cover a home's usage.
- Understanding a bill by breaking it down by appliance.
How it is calculated
Energy per day in kWh = (wattage ÷ 1,000) × hours per day × quantity. Monthly = daily × 30. Yearly = daily × 365. Cost = kWh × price per kWh.
Worked example: a 1,500-watt heater running 4 hours a day. Daily = 1.5 kW × 4 = 6 kWh. Monthly = 6 × 30 = 180 kWh. At $0.28 per kWh, that is $50.40 per month just for the heater.
Wattage on a label is the maximum draw. Many appliances, especially fridges and washing machines, cycle on and off, so average draw is lower.
What you enter, and what you get back
| Item | Details |
|---|---|
| Wattage | The power rating of each appliance in watts. |
| Quantity | How many of that appliance you have. |
| Hours per day | How long each appliance runs daily. |
| Electricity price | Your price per kWh, for the cost result. |
| Result | Daily, monthly and yearly kWh and cost, per appliance and total. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Total is higher than your bill | Wattage is the maximum draw, not average. | Reduce hours or use a plug-in energy monitor for real data. |
| Cannot find the wattage | It may be in the manual or on a label inside the door. | Search the model number online. |
| Standby usage missing | Appliances on standby draw a small amount constantly. | Add a standby appliance with 24 hours per day. |
A worked example
These are the values the calculator opens with, so you can see exactly what it does with them. Change any value on the page and the result updates; the figures below come from the same calculation.
| Input | Value |
|---|---|
| Appliance 1 | Fridge, 150 W, 1 unit, 24 hours (cycles) |
| Appliance 2 | LED TV, 80 W, 1 unit, 5 hours |
| Appliance 3 | Laptop, 60 W, 2 units, 8 hours |
| Electricity price | $0.28 per kWh |
With those inputs, the calculator returns approximately:
- Fridge: 3.6 kWh/day, 108 kWh/month, $30.24/month
- TV: 0.4 kWh/day, 12 kWh/month, $3.36/month
- Laptops: 0.96 kWh/day, 28.8 kWh/month, $8.06/month
- Total: ~4.96 kWh/day, 148.8 kWh/month, $41.66/month
Assumptions and limitations
- Uses nameplate wattage, which is the maximum draw; real average consumption is often lower for cycling appliances.
- Does not model seasonal variation in usage.
- Standby and vampire loads must be entered manually.
- An estimate, not a measurement - use a plug-in energy monitor for exact figures.
Frequently asked questions
How do I calculate energy consumption of an appliance?
Multiply the appliance's wattage in kilowatts by the number of hours it runs per day to get kilowatt-hours per day. Multiply by 30 for a monthly figure or 365 for a yearly figure. For example, a 1,000-watt appliance running 5 hours a day uses 5 kWh per day.
What is the difference between watts and kilowatt-hours?
Watts measure power - the rate at which an appliance uses energy at a given moment. Kilowatt-hours measure energy - the total amount consumed over time. A 1,000-watt heater running for 1 hour uses 1 kWh. A 100-watt bulb running for 10 hours also uses 1 kWh.
How much electricity does a fridge use?
A typical modern fridge rated at 150 to 200 watts uses about 1 to 2 kWh per day, or 30 to 60 kWh per month, because its compressor cycles on and off rather than running continuously. Older or larger fridges can use two or three times as much.
How can I reduce my energy consumption?
Target the biggest users first - usually heating, cooling, water heating and the fridge. Switch to LED lighting, improve insulation, turn off standby devices, and choose energy-efficient appliances when replacing old ones. The calculator helps you rank your appliances by cost.
Does standby power use much electricity?
Standby power is small per device - typically 1 to 5 watts - but it adds up across many devices and runs 24 hours a day. A home with 10 devices on standby at 3 watts each uses about 2 kWh per day, or roughly 730 kWh per year. It is worth eliminating with smart power strips.
How do I read my electricity meter?
For a digital meter, note down the kWh reading. Subtract last month's reading from this month's reading to get the month's consumption. For a dial meter, read each dial left to right, recording the number the pointer has just passed. If a pointer is between two numbers, use the lower one.