Electricity Cost Calculator

How to read your bill for this calculator

Almost every electricity bill in the US, UK, Canada and Australia is built from the same three pieces, even if they use different names:

• Energy (usage) charge — the kWh you used multiplied by the unit rate. In the UK this is the “unit rate” in pence per kWh; US and Canadian bills often split it into “supply” or “generation” and “delivery” lines, which you should add together.
• Fixed charge — a “standing charge” (UK) or “daily supply charge” (Australia) billed per day, or a “customer” or “service” charge billed per month (common in the US and Canada). You pay it even if you use nothing.
• Taxes and levies — usually already included in quoted residential rates. Only enter a percentage if your bill adds it as a separate line.

If your bill shows several unit rates — tiers, or time-of-use peak and off-peak prices — use the scenario tabs: put one price in Tariff A and another in Tariff B, or work out your weighted average (total energy charge ÷ total kWh) and enter that.

How the calculation works

We use an average month of 365 ÷ 12 = 30.42 days, so twelve “monthly” results add up exactly to a year. Real bills cover 28–33 days, so a single bill can differ from this estimate by a few percent even when every rate is right.

The all-in price per kWh is the number that matters when you compare offers: a tariff with a cheap unit rate but a high standing charge can cost more for a small flat than a slightly dearer unit rate with no standing charge. Try it with the tariff comparison: at low usage the fixed charge dominates; at high usage the unit rate does.

Worked example

A household uses 300 kWh in a month on a 25¢/kWh rate with a 50¢ daily charge and 5% tax added on top. Energy is 300 × $0.25 = $75.00. The fixed charge is $0.50 × 30.42 = $15.21. Tax is 5% of $90.21 = $4.51. The bill comes to $94.72, or about 31.6¢ per kWh once everything is included — 26% more than the headline rate.

Default rates and where they come from

The rate field starts with a reference value only when we have an official, dated national figure. National averages hide big regional differences, so treat them as a sanity check, not a substitute for your bill. The U.S. figure is EIA's average revenue per kWh for residential customers, which already spreads fixed charges across usage — if you use it, leave the fixed charge blank to avoid counting fixed costs twice.

Canada and Australia have no single national residential price: rates are set by provinces, states and retailers. Use the price on your bill or your regulator's published offer.

Ways to cut the bill that this calculator can test

• Compare your current tariff with a fixed or time-of-use offer by entering each as a separate tariff.
• Check how much a lower standing charge is worth at your usage before switching for it.
• Estimate the effect of using 10% less: reduce the kWh and watch the all-in price per kWh rise — fixed charges don't shrink when you save energy.

Sources

• U.S. Energy Information Administration — Electric Power Monthly, Table 5.6.A (average price to ultimate customers by state)
• Ofgem — Energy price cap unit rates and standing charges
• Australian Energy Regulator — Default market offer
• Ontario Energy Board — Electricity rates

Results are estimates based on the figures you enter and the stated assumptions. They are not financial, tax, legal or engineering advice. Spotted a problem? Tell us.