Electricity Cost Calculator

📖 Tool Introduction

The Electricity Cost Calculator helps you work out your monthly bill the moment you read the meter. Residential power in China is commonly charged on a tiered basis: the first block of kWh is priced low, any excess moves into the second block, and anything beyond that into a third, yet many people mistakenly price the entire usage at the highest block and over-estimate what they owe. This tool applies the true progressive rule, splitting your consumption band by band: after you enter this month's kilowatt-hours, the program pours the usage into each price range in turn, multiplies each slice by its own rate, and sums them into a total bill, while listing exactly how many kWh were used and how much was charged in every band, before showing the average price per unit. Both the upper cap and the unit price of every band are editable right in the table, so you can match the tariff published by your local utility, and you may add or remove bands to fit commercial or shared-meter pricing. Every calculation runs locally in your browser, with no network access and no upload of your meter readings. You can also use it to sanity-check an unusually high bill by comparing each tier's contribution, which makes it easy to see whether the jump came from crossing into a higher band or from simply using more energy overall. Because the rates are fully editable, the same layout adapts to summer and winter schedules, commercial tariffs that charge different prices by the hour, or the household combined-meter rates that some buildings apply, without ever leaving the page.

✨ Key Features

• Progressive algorithm: only the excess is priced at the higher band, avoiding over-estimation
• Editable bands: every cap and unit price can be adjusted, up to four decimal places
• Add or remove bands: extend with the add button, delete with the x, keeping at least two bands
• Itemized breakdown: the result lists usage, rate and charge for each band
• Average rate: computes the average cost per kWh for easy comparison
• Copy and download: send the breakdown to your bookkeeping app or save it as a file

📝 How to Use

1. Type this month's consumption in kWh into the usage field
2. Adjust each band cap and unit price to your local tariff, adding or removing bands as needed
3. Click Calculate Bill to see the total charge and the per-band breakdown
4. Check the average rate at the bottom to judge whether usage ran high
5. Click Example to load 350 kWh across the three default bands in one tap

⚠️ Notes

• Rates matter: the default bands are residential references; local standards differ, so use your utility's published tariff
• Ordered bands: caps should be listed small to large, since billing follows the table order
• Non-negative price: unit prices must be numbers of zero or above, otherwise a warning appears
• Usage: usage must be non-negative; empty or invalid input triggers a friendly notice
• Privacy: meter readings are computed only in your local browser with no network request