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How do I calculate my electricity bill?

Multiply each appliance’s watts by the hours it runs per day and divide by 1,000 to get kWh per day; sum every appliance, multiply by 30 for the month, then by your rate per kWh. AnyTool Electricity Bill Calculator does this live in your browser: build a whole-home appliance list (or use a single appliance, or type the monthly units straight from your meter), price it at a flat rate or a tiered slab tariff, add a fixed charge and tax, and it ranks every appliance by cost and shows the slab-by-slab breakdown.

  • kWh/day = watts × hours ÷ 1000; monthly kWh = daily × 30
  • Cost = kWh × rate per unit; flat or tiered slab tariff supported
  • Whole-home appliance list with a preset wattage library + cost ranking
  • Add fixed monthly charges and a tax/duty percentage
  • 100% in your browser — no upload, no signup, works offline

What is

Kilowatt-hour (kWh)

A kilowatt-hour is the amount of energy a 1,000-watt appliance uses in one hour, and it is exactly one “unit” on a domestic electricity meter. An appliance’s daily energy is its power in kilowatts multiplied by the hours it runs (watts × hours ÷ 1000), and the bill is that energy priced per kWh — either at a single flat rate or, under a tiered/slab tariff, with each band of units charged at its own rate plus any fixed charge and tax.

Calculators

Related terms

WattKilowatt-hourTiered tariffSlab rateFixed chargeEnergy consumption

Frequently Asked Questions

Multiply its watts by the hours used per day, divide by 1,000 for kWh per day, then multiply by 30 and your rate per kWh for the monthly cost.

To find an appliance’s running cost, take its wattage (on the label or in the manual), multiply by the hours you use it each day, and divide by 1,000 to get kilowatt-hours per day. Multiply by 30 for the month, then by your electricity rate per kWh. For example, a 1,500-watt air conditioner run 6 hours a day uses 9 kWh daily, about 270 kWh a month; at a rate of 0.13 per unit that is roughly 35 a month. AnyTool does this live and lets you list every appliance at once.

Your units are split into bands and each band is priced at its own rate — for example 0–100 units cheap, 101–300 dearer, 300+ dearest — then summed.

A tiered (slab or inclining-block) tariff does not charge one flat rate for every unit. Instead your monthly consumption is split into bands and each band is priced separately: say the first 100 units at one rate, the next 200 at a higher rate, and everything above 300 at a higher rate still. The energy charge is the sum of (units in each band × that band’s rate), to which fixed charges and tax are added. AnyTool Electricity Bill Calculator lets you build any number of slabs and shows the slab-by-slab breakdown so you can see exactly how the bill is composed.

Appliance wattage varies by model, cycling devices rarely run at full power, and real bills add fixed, demand, tax and time-of-use charges that vary by provider.

An estimate uses typical wattages and assumes a steady running power, but real consumption differs: a fridge, AC or heater cycles on and off and averages far less than its peak rating, and wattage varies by model, size and efficiency. Real bills also carry provider-specific pieces — fixed/standing and connection charges, demand charges, taxes and duties, fuel-cost adjustments, net-metering credits, and time-of-use peak/off-peak rates that change the price by the hour. Treat the figure as a budgeting estimate and read your provider’s tariff schedule for an exact bill.

Yes — it is free with no signup, and every calculation runs in your browser, so the appliances and rates you enter are never uploaded.

AnyTool Electricity Bill Calculator is completely free with no account or limits. All the maths runs in a small, unit-tested engine inside your browser, so the appliances, wattages, hours and tariff you enter are never sent to a server. You can switch currency, copy a clean summary of the result, and the page works offline after first load.

Detailed Explanation

Methodology

How the Electricity Bill Calculator Works

The calculator rests on one identity: energy in kilowatt-hours equals power in kilowatts times hours of use, so an appliance’s daily energy is watts × hours/day ÷ 1000. In appliance-list mode it sums this across every appliance (each with a quantity), in single mode it uses one appliance, and in total mode it takes the monthly units straight from the meter. Monthly energy is daily × 30 and yearly is daily × 365. The energy is then priced under the chosen tariff and the fixed charge and tax are added, all by a pure, unit-tested engine that runs in the browser.

  • kWh/day = watts × hours ÷ 1000; one kWh = one meter unit
  • Monthly kWh = daily × 30; yearly kWh = daily × 365
  • Appliance list sums all devices and ranks them by cost
  • Three input modes: single appliance, full list, or total kWh
  • All math is client-side JavaScript with no server round-trip
How It Works

Flat and Tiered (Slab) Tariffs

Electricity is priced one of two ways. A flat tariff charges a single rate for every unit: energy charge = kWh × rate. A tiered or slab (inclining-block) tariff splits the month’s units into bands and prices each band separately — for example the first 100 units at one rate, 101–300 at a higher rate, and everything above 300 at a higher rate still — so the energy charge is the sum of (units in each band × that band’s rate). The calculator lets you build any number of slabs, leaving the top band open-ended, and then adds an optional fixed monthly charge and a tax/duty percentage applied to energy plus fixed charge, mirroring how real bills are assembled.

  • Flat: energy charge = total kWh × one rate
  • Tiered: each unit band priced at its own rate, then summed
  • Top slab is open-ended (“and above”); breakdown shown per band
  • Fixed monthly charge added once; tax = (energy + fixed) × tax%
  • Effective rate per kWh = total bill ÷ units, shown alongside
Limitations

Why an Estimate Differs From the Real Bill

The result is a budgeting estimate, not a reproduction of a utility bill. Appliance wattage varies by model, size and efficiency, and devices that cycle — fridges, air conditioners, heaters — average far less than their peak rating, so a single steady-power assumption overstates them. Real bills also include provider-specific components the tool can only approximate: fixed/standing and connection charges, demand charges, taxes and duties, fuel-cost adjustments, net-metering credits, and time-of-use (peak/off-peak) rates that change the price by the hour. Months use 30 days and years 365 for projection, and exact figures require the provider’s own tariff schedule.

  • Wattage varies by model; cycling devices average below peak power
  • Time-of-use rates change the price by the hour — not modelled
  • Demand charges, fuel adjustments and net-metering vary by provider
  • Projection assumes 30-day months and 365-day years
  • Use your provider’s tariff schedule for an exact bill
Privacy & Security

Privacy and Offline Use

Because all computation runs in the browser, the appliances, wattages, hours and tariff you enter are never sent to a server, there is no account or tracking, and the page works offline after first load. The calculator is built on a shared, unit-tested electricity engine so its behaviour is consistent and verifiable.

Electricity bill calculation: in-browser (AnyTool) vs typical online electricity calculators
CapabilityAnyToolTypical online calculators
ProcessingRuns in your browserOften server-side
Appliance listWhole-home, unlimited rows + presetsOften one appliance at a time
Cost rankingPer-appliance, sorted, with share barsRarely shown
Tariff typeFlat or tiered slab, any number of bandsUsually flat only
Fixed charge & taxBoth supportedOften missing
Input modesSingle, list, or total kWhUsually one mode
CurrencyUSD / INR / EUR / GBPOften fixed
Works offlineYes (PWA)No
Cost / signupFree, no signupOften ad-heavy or gated

AnyTool computes the whole bill locally and uploads nothing.