HVAC Decoder
HVAC Tonnage From Model Number
Pick the brand or paste any AC, heat pump, or mini split model number and get the nominal tonnage and BTU/h, plus the SEER class and refrigerant generation when the brand's scheme encodes them. Built from manufacturer product data for 40+ brands.
Nominal capacity from a model number is a nameplate convention, not a measurement. Actual delivered capacity depends on the matched indoor unit, line set, airflow, and conditions. Always confirm against the data plate's BTU/h rating and the AHRI certificate for the matched system.
Capacity Code Reference Table
| Model code | Nominal BTU/h | Tons |
|---|---|---|
| 018 | 18,000 | 1.5 |
| 024 | 24,000 | 2 |
| 030 | 30,000 | 2.5 |
| 036 | 36,000 | 3 |
| 042 | 42,000 | 3.5 |
| 048 | 48,000 | 4 |
| 060 | 60,000 | 5 |
Mini splits use the same BTU/1000 idea but print the class directly, including sizes that are not divisible by 6: 09, 12, 15, 18, 24, 30, 36 (9,000 to 36,000 BTU/h, 0.75 to 3 tons). One ton of cooling = 12,000 BTU/h, so any code divided by 12 is the tonnage.
Brand Scheme Reference
Every scheme below comes from manufacturer product data sheets and nomenclature guides, compiled and cross-checked in July 2026. Where a source conflict or single-sourced claim exists, this decoder drops the claim rather than guessing: the ICP series prefix key, Rheem's Endeavor RD refrigerant letter, and Allied Air's 2025 A7 nomenclature are excluded until verified, and those brands decode capacity only.
| Brands | Where the capacity code sits | Also encoded | Confidence |
|---|---|---|---|
| Trane, American Standard | Characters 6-8 are the 3 digit BTU/1000 code (4TTR4036 = 036 = 3 tons). | Position 1 = refrigerant (2 = R-22, 4 = R-410A, 5 = R-454B), position 3 = AC vs heat pump, position 5 = SEER class digit. | high |
| Carrier | Trailing 2 or 3 digit BTU/1000 code after the series letters (24ACC636 = 36 = 3 tons; 38CKC036 = 036). | Leading digits: 24 = AC condenser, 25 = heat pump, 58/59 = gas furnace. Digit before a 2 digit capacity code is the SEER class in lettered series (3 = 13, 6 = 16, 1 = 21 in the 24ACC6 family). Refrigerant is not in a fixed digit. | high |
| Bryant | Final 3 digit group is BTU/1000 (126BNA036 = 3 tons). | Leading series encodes the line and SEER family (113A = Legacy 13 SEER AC, 126B = Preferred 16 SEER AC). | high |
| Payne | 3 digit BTU/1000 code, 018 to 060 (PA13NA036 = 3 tons). | Two characters after PA are the series: numeric = SEER (13 = 13 SEER); PA4S = current R-454B single stage AC family. | high |
| Heil, Tempstar, Comfortmaker, Arcoaire, KeepRite, Day & Night, Airquest | A 2 or 3 digit cluster divisible by 6, mid model, is BTU/1000 (N4A336AKA = 36 = 3 tons; FAB048GB2 = 048 = 4 tons). | Capacity only. The series prefix encodes refrigerant, unit type, and efficiency, but that key is not yet verified against the official ICP nomenclature document, so this tool does not decode it. | high |
| Goodman, Amana | 3 digit BTU/1000 code after the SEER digits (GSX130361 = 036 = 3 tons). R-32 GLXS/GLZS models keep a 2 digit code (GLXS4BA3610 = 36 = 3 tons). | GSX/ASX = R-410A condenser, GSC = R-22 era, 2 digits after the series letter = SEER. GLXS = R-32 AC, GLZS = R-32 heat pump, tier digit 4 = 14.3 SEER2, 5 = 15.2 SEER2. | high |
| Daikin | Unitary: 3 digit BTU/1000 code (DX16SA036 = 3 tons). Mini splits: BTU/1000 class printed directly (FTX12NMVJU = 12,000 BTU/h, about 1 ton). | Unitary: 2 digits after DX = nominal SEER series, next letter = stage (S = single stage). DX prefix = R-410A era per Daikin spec sheets. | medium |
| Lennox | Capacity is the dash number in BTU/1000 (XC21-036-230 = 3 tons; EL16XC1-048 = 4 tons). | SEER lives in the series name, not a dedicated digit (XC21 targets up to 21 SEER, EL16XC1 = Elite 16, ML14XC1 = Merit 14). Refrigerant is not encoded in a stable position. | high |
| Armstrong Air, AirEase, Ducane, Concord | Two digits immediately before the trailing revision letter, in BTU/1000 (4SCU16LS36P = 3 tons; 4SCU13LE136P = 3 tons). | 4 = R-410A generation, digits after SCU = SEER, stage letter: E = single stage enhanced, S = two stage, B = base, X = variable. The 2025 R-454B A7 nomenclature is not yet dual sourced and is excluded. | high |
| Rheem, Ruud, WeatherKing, Sure Comfort | Characters 5-6 are BTU/1000 (RA1636AJ1NA = 36 = 3 tons). | Position 1: R = Rheem, U = Ruud. Position 2: A = AC, P = heat pump. Positions 3-4 = SEER. The Endeavor RD refrigerant letter key (Y/Z) is single sourced and excluded. | high |
| York, Luxaire, Coleman (HVAC), Fraser-Johnston, Guardian | Capacity digits are BTU/1000; the position varies by product line (classic splits carry them at characters 4-5, e.g. YHE24B21SA = 2 tons). | Capacity only. SEER and refrigerant are not documented in a fixed model position for this family. | high |
| Intertherm, Miller, Gibson, Frigidaire, Maytag, Westinghouse, Tappan, Kelvinator | 3 digit BTU/1000 code in the model suffix, 018 to 060 (ET4BE-036K = 3 tons). | Capacity only per our sources. | medium |
| Mitsubishi Electric, Fujitsu, Gree, MrCool, Bosch, Samsung, Midea, Senville, Pioneer, Daizuki, Friedrich | The digits in the model are the BTU/h class divided by 1,000: 09, 12, 15, 18, 24, 30, 36 (MSZ-GL15NA = 15,000 BTU/h = 1.25 tons; BOVA-36 = 3 tons). | Capacity only. Friedrich odd sizes are approximate (PDH09 is actually 9,400 BTU/h). | high |
| LG | The 3 digit code is BTU/h divided by 100, not 1,000: 090 = 9,000, 120 = 12,000, 180 = 18,000, 240 = 24,000 (LS120HSV5 = 12,000 BTU/h = 1 ton). | Capacity only. Note LG uses a different divisor than every other brand here. | medium |
| Bard | Characters 2-3 are BTU/1000 on W-series wall mounts (W36HF-A00 = 3 tons; W60HF-A00 = 5 tons). | Capacity only per our sources. | high |
Sources per scheme: Trane: Trane nomenclature per pickhvac and Trane/American Standard product listings and spec sheets. Carrier: Carrier 24ACC6 product data and the howtolookatahouse Carrier tonnage guide. Bryant: Bryant PDS126B and PDS113A product data sheets. Payne: Payne PA13 product data (titled 1-1/2 to 5 tons, 018-060) and payne.com PA4S product page. Heil: Capacity rule dual sourced (howtolookatahouse Heil guide, ICP spec sheets). Prefix key pending verification against ICP_Nomenclature.pdf. Goodman: Goodman model nomenclature (building-center), Goodman GSX13 spec sheet, and Goodman R-32 GLXS/GLZS launch documentation. Daikin: Daikin DX16SA specification sheet and FTX/RX submittal sheets. Lennox: Lennox XC21 product listings and spec sheets (lennoxpros, hvacinformed). Armstrong Air: Armstrong Air 4SCU16LS product page and the howtolookatahouse Armstrong tonnage guide. Rheem: Rheem RA16 product listings (Ferguson) and the howtolookatahouse Rheem tonnage guide. York: building-center York tonnage decoder, corroborated by JCI product listings (e.g. York YXV36 3 ton listings). Intertherm: Nortek ET4BE specification sheet and the hvacdirect furnace decoder appendix. Mitsubishi Electric: Manufacturer model naming across Mitsubishi, Fujitsu, Gree, MrCool, and Bosch catalogs; convention (not an official decode chart) for Samsung, Midea, Senville, Pioneer, Daizuki, and Friedrich. LG: LG product listing convention (single sourced); treat as an estimate and verify on the nameplate. Bard: Bard W-series product listings and the InspectAPedia Bard model decoder.
Worked Examples
Position 1: digit 4 = R-410A (2 = R-22, 5 = R-454B). Position 2: T = Trane. Position 3: T = split AC condenser (W would be a heat pump). Position 5: digit 4 = SEER class 14. Positions 6-8: 036 = 36,000 BTU/h = 3 tons. Per pickhvac's Trane nomenclature guide and Trane product listings.
G = Goodman, S = split system, X = R-410A condenser (the older GSC line was R-22). Digits 13 = 13 SEER. Then 036 = 36,000 BTU/h = 3 tons, and the trailing 1 = 208/230V single phase. Per Goodman's model nomenclature and GSX13 spec sheet.
Leading 24 = AC condenser (25 = heat pump, 58/59 = gas furnace). ACC = series letters. The digit 6 before the capacity code = 16 SEER in the 24ACC6 family (3 = 13 SEER, 1 = 21 SEER). Final 36 = 36,000 BTU/h = 3 tons. Carrier does not put refrigerant in a fixed model digit; it follows from series and manufacture year. Per Carrier 24ACC6 product data.
Mini splits skip the divisible-by-6 ladder and print the BTU class directly: 15 = 15,000 BTU/h, which is 1.25 tons. The same convention runs across Fujitsu (ASU12RLS3 = 12,000), Gree (GWH12 = 12,000), MrCool (DIY-36 = 36,000), and Bosch (BOVA-36 = 3 tons). Watch LG: its codes are BTU/h divided by 100, so LS120 = 12,000 BTU/h, per LG product listings.
Why Furnace Model Numbers Break the Rule
Gas furnace model numbers encode heating input in MBH, thousands of BTU/h of gas input: 070 = 70,000, 090 = 90,000, 110 = 110,000. Many also carry a blower airflow code (16 = 1,600 CFM class) that looks like a capacity code. Neither number is cooling tonnage. Carrier flags its furnaces with the model prefixes 58 and 59, and this decoder reports those as furnaces instead of guessing a tonnage. For system cooling capacity, always decode the outdoor unit's model number. The 060 code is the one collision to watch: on an outdoor unit it means 5 tons of cooling; on a furnace it means 60,000 BTU/h of heating input.
Frequently Asked Questions
How many tons is a 036 model number?
3 tons. The 036 capacity code means 36,000 BTU/h nominal, and one ton of cooling equals 12,000 BTU/h, so 036 divided by 12 is 3 tons. The same math covers the whole residential ladder: 018 = 1.5 tons, 024 = 2, 030 = 2.5, 036 = 3, 042 = 3.5, 048 = 4, and 060 = 5 tons.
Do I use the model number or the serial number to find tonnage?
The model number. It describes what the unit is: capacity, and on many brands the SEER class and refrigerant generation. The serial number describes when the unit was built and carries no capacity information. If you need the unit's age or refrigerant era, decode the serial number instead with our serial number lookup tool.
Where is the model number on the nameplate?
On the data plate (rating plate), a metal or foil sticker on the outdoor unit's side panel near the refrigerant line connections, or inside the front panel on indoor equipment. It is labeled M/N, MODEL, or MODEL NO., usually printed directly above or beside the serial number. Use the outdoor unit's model for system cooling capacity; indoor air handlers and coils carry their own numbers.
Does the model number show the SEER rating?
On many brands, yes, as a rounded class rather than the exact rating. Trane and American Standard carry a SEER digit in position 5 (4TTR4 is a 14 class), Goodman and Amana spell it out (GSX16 = 16 SEER), Rheem and Ruud use positions 3-4 (RA16 = 16 SEER), and Lennox puts it in the series name (XC21). Carrier encodes it as a single digit in lettered series (24ACC6 = 16 SEER per Carrier product data). The exact SEER2 rating for a matched system is on the AHRI certificate, not in the model number.
Do the indoor and outdoor model numbers have to match in size?
They should be a rated match, which is not always the same digits. A 036 condenser is often paired with an 037 or 042 coil or air handler, and manufacturers publish approved combinations through AHRI. Mismatched capacity between indoor and outdoor sections costs efficiency and can hurt dehumidification, so verify the pairing in the AHRI directory rather than assuming equal codes.
My furnace model has 070 or 090 in it. Is that tonnage?
No. Furnace model numbers encode heating INPUT in MBH, thousands of BTU/h: 070 = 70,000 BTU/h input, 090 = 90,000. Some furnace models also carry a blower airflow code (16 = 1,600 CFM class) that can be misread as a capacity code. Cooling tonnage for a split system lives in the outdoor unit's model number. Carrier makes this easy to spot: model prefixes 58 and 59 are gas furnaces.
Can I size the replacement system from the old unit's tonnage?
Treat the old tonnage as a starting clue, not an answer. Industry studies have found a large share of residential systems oversized, and an oversized unit short-cycles, dehumidifies poorly, and wears out faster. The original unit may also have been sized before insulation, window, or envelope changes. Run a load calculation first: our BTU calculator estimates the load from climate zone, square footage, insulation, and windows, and a Manual J from your contractor settles it.
What if two digit groups in my model number both look like capacity codes?
It happens, especially with voltage blocks (230, 208) and series numbers next to the real capacity code. This decoder ranks every plausible group and shows its reasoning instead of guessing silently: 3 digit zero-padded groups like 036 outrank bare pairs, and leading digits are usually a product family code, not capacity. When the brand is selected, the brand's documented position wins. If two readings survive, check the nameplate's RLA or BTU/h rating to break the tie.
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The old unit's nominal size is a clue, not a load calculation. Oversized systems short-cycle and dehumidify poorly. Run the load numbers before you match a replacement.