How many watts does a 12,000 BTU aircon use?

A 12,000 BTU non-inverter draws about 1,000–1,300 watts (from EER 9.5–12). An inverter averages about 40–60% of that once the room is cool. Your unit's nameplate watts is the most accurate figure.

How much does one hour of aircon cost?

A 12,000 BTU non-inverter costs roughly 4.7–6.1 THB per hour at the >150-unit marginal rate (4.69 THB/unit incl. Ft+VAT). Smaller/inverter units cost less, bigger units more — enter yours in the calculator above for your own number.

What does running AC all night (8 h) cost per month?

See the worked example on this page: a 12,000 BTU inverter run 8 h a night costs from a few hundred THB up to nearly a thousand per month depending on your tariff (the 4-mode table computes it live). Key point: sleeping hours 22:00–06:00 fall entirely in TOU off-peak, so this is the case where TOU shines most.

Is an inverter really cheaper to run?

Yes for long continuous runs: once at setpoint an inverter averages about 40–60% of rated power. For short bursts where the room never fully cools, the difference is minimal — toggle inverter/non-inverter in the calculator to see your own gap.

What about 24-hour aircon — does a TOU meter help?

Enter 24 hours in the calculator (the long-run average is especially realistic for inverters). On TOU: off-peak is far cheaper than on-peak (3.00 vs 6.38 THB/unit), but 24-hour use spans both windows, so the verdict depends on your whole home's usage split — check the full bill with the TOU vs normal comparator and see the full schedule at TOU rates 2026.

Free tool · Official MEA/PEA rates

How much does your aircon really cost?

Pick your BTU size, inverter type and daily hours, and see the honest cost range per hour, day and month — compared across all 4 tariff modes including a TOU meter. The only Thai aircon calculator that prices TOU.

As of May–Aug 2026

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Short answer: a 12,000 BTU non-inverter draws about 1,000–1,300 watts, so one hour costs roughly 4.7–6.1 THB at the >150-unit home marginal rate (4.69 THB/unit incl. the May–Aug 2026 Ft + VAT). On a TOU meter during off-peak hours (22:00–09:00 + weekends) the same hour drops to 3.0–3.9 THB. Size, inverter type, hours and your tariff mode change the number a lot — enter yours below.

Calculate your aircon cost

3 choices + 1 number, instant result

Aircon size (BTU)

Not sure? Check the label or model name — most Thai homes use 9,000–24,000 BTU.

Aircon type

Inverter mode uses the long-run average once the room is cool (about 40–60% of rated power); the first hot hour draws near full power.

Hours per day

h/day

E.g. all night while sleeping = 8 h; round the clock = 24 h.

Your home's tariff mode

Home using ≤150 units/month (Type 1.1 — marginal 4.15 THB/unit)Home using >150 units/month (Type 1.2 — marginal 4.69 THB/unit) — most homes with AC are hereTOU meter (On-Peak 6.38 / Off-Peak 3.00 THB/unit)

All rates are the true marginal price per extra unit, incl. the May–Aug 2026 Ft (0.1623 THB/unit) + 7% VAT.

Worked example: 12,000 BTU inverter, 8 hours a night

The most-asked case — a 12,000 BTU inverter bedroom unit running all night (8 h/day, every day). Every figure below is computed live from the same official rates as the calculator above:

Power draw (honest range): 400–780 W (long-run average at setpoint) · Units per month: 96–187

Monthly aircon cost compared across 4 tariff modes
Tariff mode	THB/unit (incl. Ft+VAT)	Aircon cost/month
Tier 1.1 (≤150-unit home)	4.15	398–777 ฿
Tier 1.2 (>150-unit home)	4.69	450–878 ฿
TOU — all hours on-peak	6.38	612–1,194 ฿
TOU — all hours off-peak	3.00	288–561 ฿

How BTU converts to watts (why 12,000 BTU ≈ 1,000–1,300 W)

BTU measures cooling output, not power input. The bridge is the EER efficiency (BTU per watt): typical home units run EER 9.5–12, giving watts ≈ BTU ÷ 9.5 to BTU ÷ 12. E.g. 12,000 BTU ÷ 12 = 1,000 W (efficient model) up to 12,000 ÷ 9.5 ≈ 1,300 W (older/less efficient). Higher EER = less power for the same cooling.

The most accurate figure is the nameplate watts on the unit or its EGAT Label No.5. This calculator's ranges follow the real Thai market — the same rules as our 30-appliance cost table and the aircon cost explainer.

Why inverter mode is cheaper (and when it isn't)

A fixed-speed compressor runs full-blast/stop/full-blast, while an inverter slows its motor once the room hits setpoint, averaging about 40–60% of rated power. This calculator uses exactly that range in inverter mode — not a marketing number, but the post-cooldown average.

Caveat: during the first hot hour an inverter also draws near full power, so for short bursts the gap is small. The longer the run (e.g. 8 h overnight), the closer the average gets to the 40–60% band — and the bigger the saving.

How to use the aircon cost calculator

Pick size and type

Choose the BTU size (9,000/12,000/18,000/24,000 or custom) and whether it's an inverter or fixed-speed unit.

Enter hours and tariff

Enter daily hours of use and pick your home's tariff mode (1.1 / 1.2 / TOU meter).

Read the range + 4-mode table

See the honest cost range per hour/day/month, plus how the same unit prices under tier 1.1 / 1.2 / TOU on-peak / TOU off-peak.

FAQ

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