AC electricity consumption calculator
Put in your AC's power draw and running hours to get units per day, per month and per year — and what those units cost on your tariff.
| Breakdown | Value |
|---|
Estimate. The method and sources are on this page — check them against your own case before you act.
How it is calculated
An air conditioner's bill is just its input power multiplied by the hours it runs, converted to units. The tonnage tells you the cooling, not the electricity — the wattage does.
Units per day = watts × hours ÷ 1,000 · Units per month = daily units × days used · Cost = units × tariff
Find the real input power
The BEE label lists input power in watts. A 1.5-ton 3-star inverter split commonly draws around 1,400–1,700 W at full load; the same AC on a 5-star label is usually lower.
Multiply by running hours
1,500 W for 8 hours is 12,000 watt-hours, or 12 units a day. Thirty such days make 360 units a month.
Price the units
At ₹8 a unit, 360 units cost ₹2,880 a month. On a slab tariff the same AC can cost much more once it pushes you into a higher slab, which is why your own bill rate matters.
Typical room AC input power
| AC type | Typical input power | Units in 8 hours | Notes |
|---|---|---|---|
| 1 ton, 3-star split | 1,000–1,200 W | 8–9.6 units | Small bedroom; lower cooling load. |
| 1.5 ton, 3-star split | 1,400–1,700 W | 11.2–13.6 units | The common Indian living-room size. |
| 1.5 ton, 5-star inverter | 1,100–1,400 W | 8.8–11.2 units | Better ISEER; lower average draw. |
| 2 ton, 3-star split | 1,800–2,200 W | 14.4–17.6 units | Large room; check the wiring load. |
| 1.5 ton window, 3-star | 1,600–1,900 W | 12.8–15.2 units | Usually less efficient than a split. |
| Inverter AC on stabilised room | 50–80% of rated | Varies | Compressor slows once set temperature is reached. |
What most pages get wrong
Watts decide the bill, not tons
A 1.5-ton AC can draw 1,100 W or 1,800 W depending on its star rating and technology. The tonnage only says how much heat it removes.
Every extra hour is linear
Double the running hours and you double the units. Setting a timer for the hours you actually need is the simplest saving there is.
A 5-star AC saves units, not necessarily money upfront
A 5-star model uses roughly 15–25% less electricity than a 3-star model of the same capacity. The higher purchase price only pays back if you run the AC for many hours a year.
The marginal unit can cost more than the average
If the AC pushes your monthly use into a higher slab, the extra units are billed at the higher rate. Use the marginal rate for a worst-case estimate.
Frequently asked questions
How many units does a 1.5-ton AC use in 8 hours?+
How much does it cost to run an AC for one night?+
How do I find my AC's wattage?+
Do inverter ACs use less than the calculator shows?+
Is it cheaper to run the AC at 24°C or 26°C?+
Can rooftop solar cover my AC load?+
Sources, dates and a changelog.
Every number this calculator uses is either an input you control or a value from the sources below. The formula is compiled and tested at build time, so the page cannot ship with a broken calculation.
Sources
This page
- Last verified: 29 October 2026
- Next review: 29 April 2027
- Vertical: Solar & Energy
- Build tests: 3 passed
- Changelog: 1 entry
How we handle errors
- Spotted a mistake? Report it — we correct and log it.
- Corrections appear in the changelog below.
- Read the methodology and the disclaimer.