Shown on your bill as average daily use.
Appliance 1
One dryer load, one dishwasher cycle.
The per-kWh figure on your bill.
Fixed. You pay it at zero usage.
Advanced options
40–60 W is typical. 0 to skip.
Self-consumed solar. 0 to skip.
240 in AU/UK, 120 in North America.
This electricity cost calculator separates the fixed daily supply charge from what you actually use — which is why the rate on your bill isn’t the rate you’re really paying, and why cutting usage does less for a small bill than you’d expect.
The short answer
A bill is supply charge × days + kWh × rate. At 20 kWh a day, 33c/kWh and a $1.10 daily supply charge, a quarter comes to $700.70.
But your effective rate is 38.5c, not 33c. And a low user at 2 kWh a day pays an effective 88c per kWh — because 63% of their bill is the fixed charge.
On this page
How to use this electricity cost calculator
Four modes:
- Daily usage — the average daily kWh figure printed on your bill
- Appliances — build up a household from individual devices, or cost a single one
- Meter readings — two readings and the days between them
- Time of use — compare peak, shoulder and off-peak for a shiftable load
Set your usage rate and daily supply charge from your bill — both are on it, though the supply charge is usually in smaller print. Getting the supply charge right is what makes the result honest.
The supply charge changes everything for small users
Electricity bills have two parts, and most calculators model only one.
The supply charge (also called a service, standing or connection charge) is a fixed daily fee for being connected. You pay it whether you use 50 kWh or nothing at all. The usage charge is the per-kWh rate everyone quotes.
| Daily use | Supply | Usage | Quarterly bill | Effective rate | Supply share |
|---|---|---|---|---|---|
| 2 kWh | $100.10 | $60.06 | $160.16 | 88.0c | 63% |
| 5 kWh | $100.10 | $150.15 | $250.25 | 55.0c | 40% |
| 10 kWh | $100.10 | $300.30 | $400.40 | 44.0c | 25% |
| 15 kWh | $100.10 | $450.45 | $550.55 | 40.3c | 18% |
| 20 kWh | $100.10 | $600.60 | $700.70 | 38.5c | 14% |
| 30 kWh | $100.10 | $900.90 | $1,001.00 | 36.7c | 10% |
| 50 kWh | $100.10 | $1,501.50 | $1,601.60 | 35.2c | 6% |
33c/kWh usage rate, $1.10 daily supply charge, 91-day quarter.
Dividing your bill by your kWh doesn’t give your tariff. It gives an effective rate that includes the fixed charge — 88c for a small user on a 33c plan. People compare that number against a retailer’s advertised rate and conclude they’re being overcharged.
For a low user, cutting consumption has limited effect. Halve your usage at 2 kWh a day and the bill falls from $160 to $130, not to $80 — most of it was arriving regardless. At that level, comparing retailers on the supply charge matters more than the usage rate, which is the opposite of the usual advice.
Watts, kilowatt hours and dollars
The confusion here is genuine and worth being clear about: watts measure power, kilowatt hours measure energy. Power is the rate; energy is the rate times time.
kWh = Watts × Hours ÷ 1,000
Cost = kWh × Rate
Watts = Volts × Amps
Your bill charges the kWh, never the watts
A 2,400 W heater uses 2.4 kW while running. Run it six hours and it’s used 14.4 kWh — about $4.75 at 33c.
This is why a 2,200 W kettle costs almost nothing (it runs two minutes) while a 150 W fridge is one of the most expensive things in the kitchen (it never stops). Duty cycle matters more than nameplate wattage.
What appliances actually cost
| Appliance | Watts | Hours/day | kWh/day | Per year |
|---|---|---|---|---|
| Air conditioner | 2,400 | 6 | 14.40 | $1,734 |
| Electric heater | 2,000 | 6 | 12.00 | $1,445 |
| Hot water system | 3,600 | 3 | 10.80 | $1,301 |
| Pool pump | 1,100 | 8 | 8.80 | $1,060 |
| Fridge | 150 | 24 | 3.60 | $434 |
| Clothes dryer | 3,000 | 1 | 3.00 | $361 |
| Electric oven | 2,400 | 1 | 2.40 | $289 |
| Dishwasher | 1,200 | 1 | 1.20 | $145 |
| TV, 55 in | 120 | 5 | 0.60 | $72 |
| Kettle | 2,200 | 0.25 | 0.55 | $66 |
| Washing machine | 500 | 1 | 0.50 | $60 |
| Laptop | 50 | 8 | 0.40 | $48 |
| LED bulb | 10 | 6 | 0.06 | $7 |
Note the kettle and the fridge. The kettle draws fifteen times the power of the fridge and costs a seventh as much, because the fridge runs continuously. Anything that runs all day belongs at the top of your attention list regardless of how modest its wattage looks.
Heating and cooling dominate everything else — an air conditioner run six hours a day is more than the fridge, dryer, oven, dishwasher, TV, kettle, washing machine and laptop combined.
Standby power
Devices that are “off” but plugged in still draw power. Individually it’s trivial; collectively it isn’t.
| Device | Standby watts | Per year |
|---|---|---|
| Set-top box | 15 | $43 |
| Game console | 10 | $29 |
| Modem / router | 8 | $23 |
| Desktop PC asleep | 5 | $14 |
| Microwave clock | 3 | $9 |
| Coffee machine | 2 | $6 |
| TV | 1.5 | $4 |
| Phone charger | 0.5 | $1 |
| Total | 45 W | $130 |
45 W continuously is 394 kWh a year — around 5.4% of a 20 kWh/day household, spent on devices nobody is using. A switched power board on the entertainment unit is the cheapest saving available in most houses, though check nothing on it needs to stay powered.
Time of use
On a time-of-use tariff the same kilowatt hour costs different amounts depending on the clock:
| Period | Rate | 3 kWh dryer load | 4× a week, per year |
|---|---|---|---|
| Peak (2–8pm) | 55.0c | $1.65 | $343 |
| Shoulder | 30.0c | $0.90 | $187 |
| Off-peak (10pm–7am) | 18.0c | $0.54 | $112 |
Peak is 3.1× off-peak. Moving four dryer loads a week out of peak saves $231 a year from a timer setting.
Dryers, dishwashers, pool pumps, hot water and EV charging can run on a timer. Heating, cooking and lighting mostly can’t — they happen when you need them, which is usually peak.
If your load is largely unshiftable, a time-of-use tariff can cost more than a flat rate. Before switching, work out honestly how much of your consumption you can move.
Why solar can’t take a bill to zero
Solar reduces the usage charge. It does nothing to the supply charge.
Even at net zero consumption you’d still pay $401.50 a year at $1.10 a day just to stay connected. Any quote promising a zero bill is either ignoring the supply charge or assuming you disconnect entirely.
Worth understanding alongside the solar panel calculator, which shows the other half of the picture — that what you save depends far more on using power as it’s generated than on how many panels you fit.
Reading your meter
Meter readings give you real consumption rather than an estimate, which matters when you’re chasing a specific appliance or checking a suspiciously high bill.
- Take a reading and note the date and time.
- Take another a week later, or a day for a single-appliance test.
- Subtract and divide by days for your daily average.
- To isolate an appliance, read the meter, run only that appliance for a measured period, then read again.
A plug-in energy meter is more practical for individual devices and cheap. It also catches surprises — appliances frequently draw considerably more or less than their rating plate suggests.
Where the savings actually are
Biggest
Heating and cooling
More than everything else combined in most houses. One degree on the thermostat is worth more than any number of standby switches.
Easiest
Timers on big loads
Pool pump, hot water, dryer. Shifting to off-peak or solar hours costs nothing and saves hundreds.
Overrated
Standby, for big users
$130 a year is real, but it’s 5% of a large bill. Worth doing after the first two, not instead of them.
Electricity bill mistakes to avoid
- Dividing your bill by kWh to find your rate. That includes the supply charge.
- Ignoring the supply charge when comparing retailers. For low users it’s most of the bill.
- Confusing watts with kilowatt hours. Watts is the rate, kWh is the total.
- Judging appliances by wattage alone. Duty cycle matters more — see kettle vs fridge.
- Switching to time-of-use without shiftable load. It can cost more than flat.
- Expecting solar to zero the bill. The supply charge is untouchable.
- Chasing standby before heating and cooling. Right idea, wrong order.
- Trusting a rating plate. Real draw often differs; measure it.
Frequently asked questions
How do I calculate my electricity bill?
Daily kWh × days × usage rate, plus the daily supply charge × days. At 20 kWh a day, 33c/kWh and a $1.10 supply charge, a 91-day quarter is $600.60 of usage plus $100.10 of supply — $700.70 total.
What is a supply charge?
A fixed daily fee for being connected to the network, sometimes called a service or standing charge. You pay it regardless of usage — around $401 a year at $1.10 a day. It’s why your effective rate per kWh is always higher than your tariff rate.
Why is my effective rate higher than my tariff?
Because the fixed supply charge is spread across however many kWh you use. At 20 kWh a day a 33c tariff works out at 38.5c effective. At 2 kWh a day it’s 88c, since the supply charge is 63% of that bill. Dividing your bill by your usage doesn’t give your tariff.
How do I calculate watts to kWh?
Watts × hours ÷ 1,000. A 2,400 W air conditioner run six hours uses 14.4 kWh. Watts measure power — the rate — while kilowatt hours measure energy, which is what your bill charges for.
What appliance uses the most electricity?
Heating and cooling, by a wide margin. An air conditioner at 2,400 W for six hours a day costs around $1,734 a year — more than the fridge, dryer, oven, dishwasher, TV, kettle, washing machine and laptop combined. Hot water and pool pumps come next.
Why does my fridge cost more than my kettle?
Because it never stops. The kettle draws 2,200 W against the fridge’s 150 W — fifteen times as much — but runs for two minutes a day while the fridge runs continuously. Duty cycle matters more than nameplate wattage.
How much does standby power cost?
Around $130 a year for a typical household. About 45 W drawn continuously across set-top boxes, consoles, modems, chargers and anything with a clock adds up to 394 kWh a year — roughly 5.4% of a 20 kWh/day household.
Is a time-of-use tariff worth it?
Only if you can shift load. Peak can be 3.1× off-peak, so moving four dryer loads a week out of peak saves about $231 a year. But if your consumption is mostly heating, cooking and lighting — which happen when they happen — time-of-use can cost more than a flat rate.
Can solar reduce my bill to zero?
No. Solar offsets the usage charge but not the daily supply charge, which is about $401 a year and payable even at net zero consumption. Any quote promising a zero bill is either ignoring it or assuming full disconnection.
How do I work out what an appliance costs to run?
Watts × hours per day ÷ 1,000 × your rate. A 1,100 W pool pump running eight hours is 8.8 kWh a day, about $2.90, or $1,060 a year at 33c. Real draw often differs from the rating plate, so a plug-in energy meter is worth having.
How do I read my electricity meter?
Note the reading and date, take another a week later, subtract and divide by days for your daily average. To isolate one appliance, read the meter, run only that appliance for a measured period, and read again. A plug-in meter is easier for individual devices.
How do I convert amps to watts?
Watts = volts × amps. At 240 V a 10 A appliance draws 2,400 W; at 120 V the same 10 A is 1,200 W. Voltage is 230–240 V in Australia, the UK and most of Europe, and 120 V in North America — so the same amperage means very different power.
Sources and method
- Bills modelled as fixed supply charge plus variable usage, which is how retail electricity is billed in Australia, the UK and most of the US
- Appliance wattages are typical mid-range figures — actual draw varies considerably by model, age and efficiency rating
- Standby figures reflect common device categories; a plug-in energy meter gives your own numbers, which are usually more useful
- Rates used throughout are illustrative. Enter your own from your bill, including the supply charge, which is often in smaller print
- Tiered or block tariffs, demand charges and controlled-load circuits are not modelled — check whether your plan uses any of them
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How this electricity cost calculator works out its numbers
The bill is built as two separate components — supply charge times days, and kilowatt hours times rate — then added, with any pay-on-time discount applied to the total. The effective rate divides that total by the kWh consumed, which is the figure people actually experience and rarely see stated.
Appliance mode computes watts × hours ÷ 1,000 per device and sums them, showing each one’s daily kWh, daily cost, annual cost and current draw in amps. Selecting a preset fills the wattage field, which you can then override — useful when your own appliance differs from the typical figure.
Meter mode takes the difference between two readings over a known period, which gives real consumption rather than an estimate. Time-of-use mode holds the load constant and varies only the rate, isolating the value of shifting.
These are estimates from typical figures. Appliance draw varies substantially by model and age, and thermostat-controlled devices like fridges and air conditioners cycle rather than running continuously at rated power — so treat those as upper bounds on running hours. Tiered tariffs, demand charges and controlled-load circuits aren’t modelled here. Your bill is the authority; use it to set the inputs.