Electricity Unit Cost Calculator — kWh from Wattage
Every appliance argument in a Pakistani household — whose AC, whose iron, whose gaming PC — resolves with the same three numbers: wattage, hours, and the tariff. Watts times hours over a thousand is kWh; kWh times the rate is rupees. This tool runs the conversion for any appliance so the argument can move to facts.
Where do I find an appliance’s wattage?
The rating plate — a sticker or engraving near the power cord or on the base — lists watts directly or volts and amps (multiply them). Common Pakistani household figures: ceiling fan 75–90 W, fridge 150–250 W running, iron 1,000–1,500 W, 1.5-ton AC 1,300–1,900 W depending on inverter technology.
Which per-unit rate should I enter?
Your bill’s total divided by its units gives your true blended rate including adjustments — usually Rs. 35–45 for non-protected domestic consumers in 2026. The default of 38 is a reasonable national stand-in when the bill isn’t handy.
Why does my fridge cost less than this tool suggests?
Compressor cycling — a fridge rated 200 W runs the compressor perhaps a third of the time, so its effective continuous draw is far lower. For cycling appliances (fridges, ACs on thermostat, water dispensers), enter a third to half the plate wattage, or use our dedicated AC tool which models it.
Electricity Unit Cost Calculator
The formula and the three places it goes wrong
Watts × hours ÷ 1,000 × rate is exact arithmetic; the errors live in the inputs. First, plate wattage is maximum draw — cycling appliances average far below it. Second, hours are systematically underestimated for background appliances; the "two hours" of TV is often five. Third, the rate people remember is last year’s — pull it from the current bill. With honest inputs, this tool’s monthly figure lands within a few percent of metered reality.
Turning the numbers into a smaller bill
The audit pattern that works: run every major appliance through this tool, rank by monthly rupees, and attack the top three only. The top of the list is nearly always cooling and heating — where inverter technology, thermostat discipline, and insulation each cut meaningful percentages — while the long tail of LED bulbs and phone chargers isn’t worth optimisation effort. One ranked list converts the monthly bill from a mystery into a budget with named line items.
A worked example: the iron versus the fan debate
A 1,200 W iron used 45 minutes daily is 0.9 kWh — about Rs. 34 a day, Rs. 1,000 a month, which surprises most households. The 80 W fan running ten hours costs less per day than the iron’s 45 minutes. The general lesson transfers: short bursts of high-wattage heating appliances (irons, kettles, hair dryers) quietly rival the all-day low-wattage loads everyone watches, and batching the ironing into two weekly sessions genuinely shows up on the bill.
The same batching logic applies to the washing machine’s heater setting and the kettle’s refill habit — heat is expensive everywhere it appears.
Treat any appliance that makes heat as guilty until this tool clears it.
More questions answered
In order: air conditioning (dominant whenever it runs), electric geysers, irons used daily, and old non-inverter fridges. The surprise entries are standby loads — a houseful of chargers, routers, and TVs on standby quietly burns 20–40 units monthly.
An 80 W fan for 10 hours is 0.8 units — about Rs. 30 a night at typical rates, or roughly Rs. 900 a month. The fan is famously cheap; the same night of 1.5-ton AC runs fifteen to twenty times that.
Only at equal hours. A 2,000 W instant geyser running 20 minutes costs less than a 1,200 W storage geyser cycling all day. Watts measure intensity; the bill measures intensity times time — duty hours matter as much as the plate.
A plug-in kWh meter (Rs. 1,500–3,000 in any electronics market) reads cumulative units for whatever you plug through it — the definitive answer for cycling or suspect appliances, and the fastest way to find the mystery load inflating a bill.