You measured the room. You searched for a number. Three different sites gave you three different answers, and the supplier is waiting.
The bottom line first. One ton of cooling handles roughly 20 to 25 square meters of ordinary Philippine bedroom or small office, and one ton equals 1.5 HP in the way aircon is rated and sold here. So a 40 square meter space needs about 2 tons, or 3 HP. If you are asking how many tons of aircon do I need for anything with people, kitchen equipment, or a fresh air requirement, that figure will be low, sometimes by half.
What follows is the conversion nobody explains, why the Philippine sizing charts disagree with each other so badly, what actually moves the number, and the point where a chart stops being a safe basis for buying equipment.
What Does One Ton of Aircon Actually Mean?
A ton is a measure of cooling capacity, not weight. One ton of refrigeration equals 12,000 BTU per hour, and a BTU, or British thermal unit, is the heat needed to raise one pound of water by one degree Fahrenheit. British thermal units are how every air conditioning unit on the market states its output.
Here is the part that trips people up in this market. Philippine split units are sold in horsepower, and the HP figure on the box is a market convention for capacity class, not a measurement of cooling output. Real mechanical horsepower is 746 watts. A unit labelled 1.0 HP delivers around 9,000 BTU per hour, which is closer to 2.6 kilowatts of cooling.
The working conversions for Philippine consumer equipment run like this. A 1.0 HP unit is about 9,000 BTU per hour, 1.5 HP is about 12,000, which is exactly one ton, 2.0 HP is about 18,000, and 2.5 HP is about 24,000, or a two-ton unit. Ratings vary a little between brands, so check the nameplate rather than assuming.
So when somebody asks in tons and the shop quotes in HP, multiply the tons by 1.5. Residential air conditioner ratings here are quoted in HP almost without exception, and that single conversion resolves most of the confusion we hear on site.
How Many Tons of Aircon Do I Need Per Square Meter?
For ordinary residential and small office spaces, plan on one ton for every 20 to 25 square meters. For restaurants, retail, and classrooms, expect to need considerably more capacity for the same floor area.
The residential figures in common Philippine use work out roughly as follows.
- A 0.5 HP unit suits a small bedroom of about 10 to 12 square meters, the kind of room with one window and one occupant.
- 1.0 HP covers most standard bedrooms, somewhere between 12 and 18 square meters depending on which guide you read.
- 1.5 HP, which is your one ton, handles a master bedroom or a small enclosed office in the 18 to 25 square meter range.
- 2.0 HP moves you into large bedrooms and modest living rooms, roughly 26 to 36 square meters.
- Above that, most Philippine homes and small offices step into 2.5 HP or split the space between two units, which is often the better answer for an L-shaped or open-plan layout.
Those numbers assume a ceiling around 2.7 metres, two or three occupants, ordinary window area, and no requirement to bring in outdoor air. Change any of those and the aircon capacity per room size shifts, sometimes sharply. A 30 sqm space, for example, sits near 1.5 tons once you allow for a second occupant and any afternoon sun.
Why the American Square Feet Rule Does Not Transfer
Because it was written for a different climate zone and a different kind of system. The general rule of thumb on most US pages is to multiply your square footage by 20 to 25 BTU, then divide by 12,000 to reach tonnage. Applied to a Philippine room, that rule undersizes badly.
Run the conversion yourself. One square meter is 10.76 square feet, so 25 BTU per square foot works out to roughly 270 BTUs of heat per square meter. Philippine practice commonly uses 500 to 600 BTU per square meter for the same kind of room. The American general rule lands at close to half.
The gap has causes worth understanding. US sizing balances heating and cooling across a full year and assumes a central air conditioner sized to cool your home as one system, where unoccupied rooms get averaged into the total. Home air conditioning there is a whole-house problem. Here it is a room-by-room one, in a climate with no heating season, very often under an uninsulated concrete roof deck.
This is also why a free AC tonnage calculator built for the US market will tell you a 40 square meter area needs about one ton, while local practice puts the same area nearer two. Neither figure is dishonest. They answer for different buildings. If you are buying an air conditioner for your home or your branch here, use the Philippine numbers and treat the American ones as a lower bound.
Why Every Aircon Sizing Chart in the Philippines Gives a Different Answer
Because the charts are written for different assumptions and none of them state what those assumptions are. We compared the sizing tables published by seven Philippine aircon retailers, service companies, and calculator sites. For the same 1.0 HP unit, the recommended room size ranged from 11 square meters on the most conservative page to 30 square meters on the most generous.
That is close to a threefold spread for identical equipment. Anyone searching how many tons of aircon do I need gets a different answer depending on which page loads first, with nothing on the page to say which one fits their room. A reader who lands on the generous chart and buys accordingly ends up with a unit running flat out, never reaching setpoint on an April afternoon, and pulling more electricity than a correctly sized one would.
The spread is not carelessness. One chart assumes an interior condo bedroom with neighbours above and below. Another assumes a ground floor room under an uninsulated roof deck. Both are honest numbers for the room the writer had in mind. Neither tells you which room that was.
This is the real limit of any horsepower to square meter aircon table. Floor area stands in for load, and it only works while everything it is standing in for stays constant.
What Changes the Number Besides Floor Area
Six things move the answer to how many tons of aircon do I need more than square meters do, and most of them are visible on a floor plan. Factors like insulation and orientation carry more weight than area alone, and there are many other factors below that threshold worth checking before you buy.
- Ceiling height. A room with a 3.5 metre ceiling holds far more air than one at 2.7 metres. Condo lofts and older houses in places like San Juan and Quezon City routinely need a size up for this reason alone.
- West-facing glass. Afternoon sun through unshaded west glass is the heaviest single gain on most Philippine rooms. The number of windows matters less than which way they face, and the same 20 sqm bedroom facing east and facing west are not the same cooling problem.
- What is above the room. A top floor room under an uninsulated concrete roof deck can need 30 to 40 percent more cooling capacity than the identical room on a middle floor. Choosing to insulate the deck is usually cheaper than the extra tonnage and the electricity it burns for the next decade.
- People. Each occupant adds both heat and moisture. A bedroom for two and a meeting room for twelve at the same floor area are far apart.
- Equipment. Servers, kitchen appliances, display chillers, and commercial coffee machines add load continuously. We have seen a small coffee shop need double the tonnage its floor area suggested, entirely because of equipment.
- Fresh air. Any space where a code or a client standard requires outdoor air carries a moisture load that no residential chart accounts for. In Metro Manila this is the largest single miss.
That last one deserves a number. PAGASA’s climatological normals for 1991 to 2020 at the Port Area station in Manila put relative humidity at 82 percent in August and 74 percent across the year, with mean maximum temperature reaching 33.8°C in April. Air that humid carries a heavy moisture load, and removing that moisture takes real capacity. Our companion post on how to compute HVAC load works through the arithmetic.
How Many Tons Does a Commercial Space Need?
More than a residential chart will tell you, usually by a wide margin. Occupancy and equipment drive commercial tonnage, and floor area becomes a weak predictor once either one climbs.
Rough expectations from projects we have worked on, offered as ranges to check against rather than as design values:
- Open-plan offices land near one ton per 18 to 25 square meters, with glass area and tenant density moving it either way. Our work at The Linear in Makati sat in that band.
- Restaurants often need double an office of the same size once you account for diners, kitchen heat, and the makeup air needed to balance the exhaust hood. The restaurant MEPF design page covers how that gets coordinated.
- Coffee shops surprise owners most. A 60 square meter branch with espresso machines, undercounter chillers, and an ice maker is a heavier load than a 60 square meter office. We go into this on the coffee shop MEPF page.
- Classrooms carry high occupant density for a few hours and sit empty the rest of the day, which makes the peak high and the running hours short. School and institutional projects are usually sized around the peak and controlled around the pattern.
- Retail depends almost entirely on the lighting and display load the brand specifies, which often arrives after the mechanical scope was priced.
Asking how many tons of aircon do I need for a commercial fit-out and answering it from a residential chart is the most common sizing error we are called in to correct. Most commercial zones we size land somewhere between 1.5 to 5 tons each, and the square meters per ton fall steadily as occupancy rises. AC sizing for a fit-out follows the cooling needs of the operation, not the area on the lease.
Should You Round Up or Round Down?
Round up slightly with an inverter unit, and be careful about rounding up at all with a non-inverter one. Oversizing is not the safe option people assume it is in this climate. If a room falls between two ratings, choose a unit one step larger only when it is an inverter.
An oversized unit with a fixed-speed compressor reaches the desired temperature quickly and shuts off. Short run times mean the coil never stays cold long enough to dehumidify the space. The room reads 24°C and still feels damp, and on ceiling tiles and diffusers that shows up eventually as visible mold. We have specified a smaller air conditioner as the fix for that more than once.
An undersized unit fails the other way. It will run constantly without ever holding setpoint on a hot afternoon, which shortens compressor life and shows up on your energy bills every month.
Inverter units behave differently from both. They modulate compressor speed instead of cycling, so a modest amount of extra capacity runs at part load rather than switching on and off, and the dehumidification holds up. Getting the correct size matters more for comfort and efficiency than any energy efficiency rating on the sticker, because a highly rated air conditioner sized wrong still performs badly.
There is a running cost attached to getting this wrong. Meralco’s rate advisory of 10 July 2026 put the overall residential rate at P14.8261 per kilowatt hour, up from P14.4833 in June. Air conditioning is the largest single load in most Philippine buildings, so an AC unit that runs continuously because it was undersized, or cycles badly because it was oversized, costs you money for the life of the equipment.
When Does a Sizing Chart Stop Being Enough?
The moment your project needs a mechanical permit. At that point tonnage is not selected from a table, it is calculated and sealed by a Professional Mechanical Engineer. The only reliable way to size an air conditioning system for a permitted space is to compute the load, and the HVAC system you install then has to match the sealed drawings.
RA 8495, the Philippine Mechanical Engineering Act of 1998, requires mechanical designs, plans, and specifications to be prepared under the responsible charge of a PME and to carry that engineer’s seal. Section 302.3 of the Revised IRR of PD 1096, the National Building Code, carries the same requirement into the building permit process, and the Philippine Mechanical Engineering Code requires the engineering calculations to be submitted with the application.
So the honest answer to how many tons of aircon do I need changes depending on what you are doing. Buying a split unit for a bedroom, use the chart and check the ceiling height. Fitting out a branch, a clinic, a classroom, or a floor of an office tower, you need an aircon tonnage computation that will survive review, which means a professional load calculation rather than a table lookup.
Working with an HVAC professional early is cheaper than it sounds, because a proper load calculation usually reduces the tonnage a supplier quoted rather than increasing it. Suppliers round up to be safe. Engineers compute the right tonnage and let the equipment schedule follow.
Requirements and reviewer expectations do vary between LGUs, and the checklist one Office of the Building Official accepts without comment may draw questions in the next city. Confirm the current requirements with the OBO covering your site before you submit.
There is a second reason this matters, and it has nothing to do with compliance. Tonnage sets the electrical load. Change the tonnage late and the breaker sizing, feeder sizes, and sometimes the utility service application all change with it, which is why our electrical design work is coordinated against the mechanical numbers rather than after them.
Frequently Asked Questions
How many HP is 1 ton of aircon?
One ton equals 1.5 HP in Philippine aircon ratings, or about 12,000 BTU per hour. A 1.0 HP unit is roughly 9,000 BTU per hour, which is about 0.75 tons. The HP label is a capacity class used by the market, not a measure of mechanical horsepower.
What size air conditioner do I need for a 20 sqm room?
A 20 square meter bedroom with a standard 2.7 metre ceiling usually needs 1.5 HP, which is one ton. Move up to 2.0 HP if the room sits under an uninsulated roof, faces west without shading, or regularly holds more than three people.
Is it better to oversize or undersize an aircon?
Neither, though oversizing is the more common mistake here. An oversized fixed-speed unit cools fast, shuts off, and leaves the room humid. An undersized unit runs continuously and wears out sooner. Inverter units tolerate slight oversizing far better than non-inverter units do.
How many tons of aircon for a 100 sqm office?
Plan on roughly 4 to 5.5 tons for a 100 square meter open-plan office, which is about 6 to 8 HP in split units. The range depends on glass area, headcount, and equipment load. Offices with heavy west glass or dense seating land at the upper end.
Does ceiling height affect aircon size?
Yes, significantly, because cooling load follows air volume rather than floor area alone. A room with a 3.5 metre ceiling holds roughly 30 percent more air than the same floor area at 2.7 metres. Condo lofts and older houses with high ceilings usually need one size up.
Do I need an engineer to size aircon for a commercial space?
For a building permit, yes. RA 8495 requires mechanical plans and calculations to be prepared, signed, and sealed by a Professional Mechanical Engineer. You can estimate the cooling capacity requirement yourself for budgeting, but an owner’s estimate is not a permit document.
Get a Second Opinion Before the Equipment Order Goes Out
If a supplier has quoted you a tonnage and nobody has shown you the arithmetic behind it, that is worth a second look. Send us the floor plan and a short description of how the space will be used, and we will give you an estimate you can actually check, along with a plain answer on whether the number holds up.
The bottom line, restated. Charts answer for bedrooms and calculations answer for buildings, so knowing how many tons of aircon do I need really means knowing which of the two your project is. Properly sizing the equipment is what lets it cool your space, keep the space dry through August, and hold efficiency and comfort together instead of trading one for the other. Send your drawings through the proposal request form and we will come back within 48 hours with scope, timeline, and fees. If you would rather talk it through first, call us at +63 960-420-9863.