A heater costs the same to run whatever its price tag says: the cost depends on its wattage, how many hours it runs and what you pay KPLC per unit. The good news is that the sum is simple, and once you know it you can work out any heater in a minute. Here is the formula, a worked example and the quickest ways to bring the cost down.
The formula: watts, hours and your rate
Electricity is billed in units, and one unit is one kilowatt-hour. To find the units a heater uses, divide its wattage by 1000 and multiply by the hours it runs. Then multiply the units by the price you pay per unit to get the cost.
Your own rate is the number to use. Your KPLC bill and your token purchase both show it, so take it from there rather than guessing.
A worked example
Take the Venus 700W oil heater. Running for 8 hours, it uses 0.7 kilowatts times 8 hours, which is 5.6 units. Multiply 5.6 by your price per unit and you have the cost of one night.
The same steps work for any heater: read the wattage on the label, divide by 1000, multiply by the hours, then by your rate.
Why a thermostat changes the real cost
The formula gives the most a heater can use if it runs flat out the whole time. A heater with a thermostat switches itself off once the room is warm and back on when it cools, so over a night it uses less than the full figure. The Venus 700W has a thermostat, which is one reason it suits a small room.
Measure instead of guess
An energy meter socket tells you exactly what an appliance draws. The Manhua TG44ME shows voltage, current, wattage and running cost in real time, and it is rated for 16A and 3600W. Plug a heater into it for one evening and you will see its real cost rather than an estimate.
Ways to cut the bill
- Heat the room you are in, not the whole house.
- Choose the lowest wattage that warms the space.
- Use the thermostat and the lower heat setting once the room is warm.
- Close doors and curtains so the heat stays where you need it.
The cheapest heater to run
For a small room, the lowest wattage that does the job is the cheapest to run, such as the 700W oil heater. For larger rooms, an oil heater with a thermostat tends to end up cheaper over an evening than a heater that runs flat out the whole time.
Other options worth a look
Find your rate on your KPLC bill, run the formula for the heater you are considering, and use a meter to check the result.
Check the Manhua TG44ME energy meterKSh 1,700 · In stock
Which one should you pick?
Pick the MANHUA TG44ME Energy Meter Plug Socket if
- You want to see what any appliance really costs
- You want voltage, current, wattage and running cost on a screen
Pick the Venus 700W 7-Fin Oil Room Heater for Small Rooms – Quiet Energy Saving Indoor Heater if
- You heat a small room of about 8 square metres
- You want a thermostat and low wattage
Where you would use it
- Before you buy Check what a heater will cost per night so you pick the wattage your budget can carry.
- Checking your habits Plug the heater into a meter for one evening and see the real running cost.
- Landlords and offices Track which appliances use the most units before deciding what to automate.
Frequently asked questions
Divide its wattage by 1000, multiply by the hours it runs to get units, then multiply the units by your price per unit.
It uses 5.6 units if it runs flat out for 8 hours, and less if its thermostat switches it off once the room is warm.
Your electricity bill and your token purchase both show it. Use that figure in the formula.
Yes. An energy meter socket such as the Manhua TG44ME shows voltage, current, wattage and running cost in real time.
