How many watts does a 3-ton air conditioner use?

A 3-ton central air conditioner uses 2,500 to 3,500 watts during normal operation, depending on its SEER rating. A 14 SEER unit draws about 3,000 watts while a 20 SEER unit draws about 2,100 watts. On startup, expect a surge of 7,500 to 17,500 watts lasting 1 to 2 seconds.

What is the difference between running watts and starting watts for an AC?

Running watts is the continuous power an air conditioner draws while the compressor is operating. Starting watts (surge watts) is the brief power spike when the compressor first kicks on, typically 3 to 5 times the running wattage. The surge lasts less than 2 seconds. Running watts determine your electric bill and solar panel sizing. Starting watts determine your generator size, inverter capacity, and breaker requirements.

How does tonnage relate to BTU for air conditioners?

One ton of air conditioning equals 12,000 BTU per hour of cooling capacity. The term comes from the amount of energy needed to melt one ton of ice in 24 hours. So a 2-ton AC provides 24,000 BTU/hr, a 3-ton provides 36,000 BTU/hr, and a 5-ton provides 60,000 BTU/hr. Tonnage does not directly equal wattage -- a more efficient unit uses fewer watts to deliver the same BTU.

How many solar panels do I need to run a 5-ton central AC?

A 5-ton central AC uses about 18 to 22 kWh per day when running 8 hours. At 5 peak sun hours with 400W panels and an 0.83 derate factor, you need 12 to 14 panels. In a cloudy 4-PSH location, plan for 15 to 17 panels. In a sunny 6-PSH location, 10 to 12 panels will suffice.

What is SEER and how does it affect AC wattage?

SEER (Seasonal Energy Efficiency Ratio) equals total BTU of cooling output divided by total watt-hours of electricity consumed over a typical cooling season. Higher SEER means fewer watts per BTU. A 20 SEER unit uses about 30 percent less electricity than a 14 SEER unit for the same cooling output. The current federal minimum is 14 SEER2 in the northern US and 15 SEER2 in the southern US.

Which type of AC uses the least watts: window, portable, mini-split, or central?

Mini-split air conditioners use the fewest watts per ton of cooling because their inverter-driven compressors adjust speed to match the load rather than cycling on and off. Window units are next. Central AC falls in the middle. Portable air conditioners use the most watts per ton because they exhaust through a single hose, creating negative pressure that pulls warm air back into the room.

How much does it cost to run an air conditioner per hour?

Multiply the running watts by your electricity rate. A 3-ton central AC drawing 3,000 watts costs about $0.48 per hour at the national average rate of $0.16 per kWh. A window unit drawing 1,200 watts costs about $0.19 per hour. Monthly costs depend on how many hours per day the compressor actually runs, which is typically 40 to 60 percent of the time the system is on.

Can I run a central air conditioner on solar panels alone?

On a grid-tied system, yes -- your solar panels feed power to the AC during the day and you draw from the grid at night or on cloudy days. Your annual solar production can fully offset annual AC usage. For a fully off-grid setup, you need a large battery bank and an inverter rated for the surge watts. A 3-ton AC needs at least a 48V 10 kWh battery bank and a 6,000W continuous / 18,000W surge inverter.

Air Conditioner Wattage By Tonnage: Complete AC Power Chart (2026)

Air conditioner wattage ranges from 500W for a small window unit to over 6,000W for a 5-ton central system. The exact number depends on the AC type, tonnage (cooling capacity), and efficiency rating. This chart covers every common configuration so you can size your solar array, choose the right generator, or estimate your electricity costs accurately.

AC Wattage By Tonnage And Type

One ton of air conditioning equals 12,000 BTU/hr of cooling capacity. A higher SEER rating means fewer watts to deliver those BTUs. The values below assume units meeting current federal efficiency minimums.

Tonnage	BTU/hr	Window AC (W)	Portable AC (W)	Mini-Split (W)	Central AC (W)
0.5 ton	6,000	500 - 700	600 - 900	400 - 600	--
1 ton	12,000	900 - 1,200	1,100 - 1,400	500 - 800	900 - 1,200
1.5 ton	18,000	1,300 - 1,700	1,500 - 2,000	750 - 1,100	1,200 - 1,700
2 ton	24,000	--	--	1,000 - 1,500	1,600 - 2,200
2.5 ton	30,000	--	--	1,200 - 1,800	2,000 - 2,800
3 ton	36,000	--	--	1,500 - 2,200	2,500 - 3,500
3.5 ton	42,000	--	--	1,800 - 2,600	3,000 - 4,000
4 ton	48,000	--	--	2,200 - 3,000	3,500 - 4,800
5 ton	60,000	--	--	2,800 - 3,800	4,500 - 6,000

Window and portable units are only manufactured up to about 1.5 tons (18,000 BTU). For larger spaces, you need a mini-split or central system.

Running Watts vs Starting (Surge) Watts

Every air conditioner compressor draws a large inrush current at startup. This surge lasts less than 2 seconds but can be 3 to 5 times the running wattage.

AC Size	Running Watts (Central)	Surge Watts (Standard)	Surge Watts (Soft Start/Inverter)
1 ton	900 - 1,200	2,700 - 6,000	1,350 - 2,400
2 ton	1,600 - 2,200	4,800 - 11,000	2,400 - 4,400
3 ton	2,500 - 3,500	7,500 - 17,500	3,750 - 7,000
4 ton	3,500 - 4,800	10,500 - 24,000	5,250 - 9,600
5 ton	4,500 - 6,000	13,500 - 30,000	6,750 - 12,000

Why this matters: If you are running an AC from a generator, the generator must handle the surge watts or it will trip. A 3-ton AC with 3,500W running watts needs at least a 10,000W generator to handle startup. An aftermarket soft-start kit ($100-$150) can cut the surge in half.

For off-grid solar, your inverter must be rated for the surge wattage. Grid-tied systems do not have this limitation because the grid absorbs the startup spike.

EER And SEER Ratings Explained

Efficiency ratings tell you how many watts an AC unit consumes per unit of cooling output. Higher numbers mean lower power bills and fewer solar panels needed.

EER (Energy Efficiency Ratio) measures efficiency at a single test condition: 95 degrees F outdoors, 80 degrees F indoors, 50% humidity. EER = BTU/hr divided by watts. A window unit with 12 EER drawing 1,000W produces 12,000 BTU/hr of cooling.

SEER2 (Seasonal Energy Efficiency Ratio 2) measures efficiency across an entire cooling season with varying temperatures. SEER is always higher than EER because the system runs more efficiently in milder weather. A unit rated 16 SEER2 might have an EER of 12.

CEER (Combined Energy Efficiency Ratio) applies to window and portable units. It accounts for standby power draw when the unit is plugged in but not actively cooling.

SEER2 Rating	Watts Per Ton	Savings vs 14 SEER2
14 (federal minimum, North)	857	Baseline
15 (federal minimum, South)	800	7%
16	750	12%
18	667	22%
20	600	30%
22	545	36%
25+ (top tier)	480	44%

The jump from 14 SEER2 to 20 SEER2 saves roughly $200 to $400 per year on a 3-ton system running in a hot climate. Over a 15-year lifespan, that is $3,000 to $6,000 in savings.

Daily kWh By AC Type And Usage Hours

To size your solar array or estimate costs, you need daily energy consumption -- not just wattage. This table calculates daily kWh based on typical compressor duty cycles (the compressor does not run continuously even when the system is "on").

AC Type and Size	Running Watts	Hours On	Duty Cycle	Daily kWh
Window 0.5-ton	600	10	60%	3.6
Window 1-ton	1,050	10	50%	5.3
Portable 1-ton	1,250	10	55%	6.9
Mini-split 1-ton	650	12	40%	3.1
Mini-split 2-ton	1,250	12	40%	6.0
Central 2-ton	1,900	8	45%	6.8
Central 3-ton	3,000	8	45%	10.8
Central 4-ton	4,150	8	45%	14.9
Central 5-ton	5,250	8	45%	18.9

Note: Duty cycles vary by climate. In Phoenix at 110 degrees F, a central AC might run at 80% duty cycle. In Portland at 85 degrees F, it might run at 25%. The values above represent moderate hot-climate conditions.

Solar Panel Sizing For Each AC Size

Using 400W panels with an 0.83 derate factor for real-world losses (inverter efficiency, wiring, soiling, temperature derating).

AC Type and Size	Daily kWh	Panels at 4 PSH	Panels at 5 PSH	Panels at 6 PSH
Window 0.5-ton	3.6	3	3	2
Window 1-ton	5.3	4	4	3
Portable 1-ton	6.9	6	5	4
Mini-split 1-ton	3.1	3	2	2
Mini-split 2-ton	6.0	5	4	4
Central 2-ton	6.8	6	5	4
Central 3-ton	10.8	9	7	6
Central 4-ton	14.9	12	10	8
Central 5-ton	18.9	15	12	10

Formula: Panels needed = Daily kWh / (0.400 kW x PSH x 0.83).

Solar and AC are a natural match because peak solar production and peak cooling demand occur at the same time -- sunny summer afternoons. A grid-tied solar system offsets AC usage almost in real time during the hottest hours.

How To Find Your AC's Actual Wattage

The wattage ranges in the charts above are typical values. Your specific unit may differ. Here is how to find the exact number:

Check the nameplate. Look for a metal plate on the outdoor condenser (central) or the side panel (window/portable). Find the RLA (Rated Load Amps) and voltage. Watts = RLA x Voltage. Example: 14 RLA x 240V = 3,360W.
Check the EnergyGuide label. The yellow label shows estimated annual kWh. Divide by estimated cooling hours (about 1,000 for moderate climates, 2,000 for hot climates) to get average watts.
Use a power meter. For window and portable units, plug a Kill-A-Watt meter ($25-$35) into the outlet. It measures actual power draw in real time and tracks cumulative kWh.
Look up the model. The AHRI Directory at ahridirectory.org lists certified performance data including watts and EER for every residential AC unit sold in the US.

Try The Calculator

Enter your AC's wattage and your location's peak sun hours to see how many panels you need.

Solar panel wattage

Type any value 10–750 W. Common sizes: 100 W (portable), 400 W (residential 2026), 580 W (commercial).

Peak sun hours per day

hrs

Don't know your PSH? Find your exact value →
Benchmarks: U.S. avg 4.98 · Phoenix 6.54 (highest) · Seattle 3.95 · Anchorage 3.17 (lowest). Above ~5.5 = sunny · 4.5–5.5 = average · below 4.5 = cloudy.

Daily kWh production

0.00kWh

Based on a 400W panel and 5.32 peak sun hours per day

Daily

1.60kWh

average across the year

Monthly

48kWh

× 30 days

Yearly

583kWh

× 365 days

Monthly production for a 400W panel — US Average

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

kWh per month · Source: NREL PVWatts v8

216 kg

CO₂ avoided per year

0.05

equivalent US homes powered

trees planted equivalent

$93

estimated annual savings

Tap to see sensitivity analysisSensitivity analysis

Sensitivity range
Scenario	Value
Low (-20%)	1.3 kWh
Expected	1.6 kWh
High (+20%)	1.9 kWh

Your daily production scales linearly with both panel wattage and peak sun hours. A 10% change in either input changes your result by 10%.

See production for your state Try the system size calculator

Tips For Reducing AC Wattage

Upgrade efficiency. Moving from 14 SEER2 to 20 SEER2 cuts energy use by 30 percent.
Seal ductwork. Leaky ducts waste 20 to 30 percent of cooled air in attics and crawlspaces.
Add attic insulation. Going from R-19 to R-49 in the attic reduces cooling load by 10 to 15 percent.
Use ceiling fans. Fans let you raise the thermostat 4 degrees F without feeling warmer, reducing AC runtime.
Shade the condenser. An outdoor unit in direct sun works 10 percent harder than one in shade (but keep 2 feet of clearance on all sides for airflow).
Replace old units. A 20-year-old AC rated at 10 SEER uses 40 percent more electricity than a new 14 SEER2 unit.