Watts to BTU/hr Converter
Instantly convert watts to BTU per hour, kilowatts, refrigeration tons, horsepower, kcal/hr, and more — with live precision control, quick presets for common HVAC & appliance ratings, composite tons & BTU/hr display, and a downloadable PDF report.
Power conversion using the IT BTU: 1 W = 3.412142 BTU/hr, 1 refrigeration ton = 12,000 BTU/hr = 3,516.85 W, and 1 kW = 1,000 W — for reference only.
| Watts | BTU/hr | Kilowatts | Refrigeration tons |
|---|
Watts to BTU/hr Conversion — Complete Guide for 2026
Converting watts (W) to BTU per hour (BTU/hr) is how you compare electrical ratings with heating and cooling ratings. Space heaters, appliances, electronics, and metric heat-pump specs are rated in watts or kilowatts, while furnaces, air conditioners, and room-sizing guides in the US use BTU per hour and tons. The key relationship is: 1 W = 3.412142 BTU/hr, so 1 kW ≈ 3,412.14 BTU/hr and 1 BTU/hr ≈ 0.29307 W.
Our free Watts to BTU/hr Converter takes a value in watts and returns BTU per hour, splits large results into refrigeration tons plus leftover BTU/hr (5,000 W becomes 1 ton 5,061 BTU/hr), and converts across the power ladder — kilowatts, refrigeration tons, mechanical horsepower, metric horsepower (PS), and kilocalories per hour. Quick presets, a log-scale comparison chart, a common-ratings reference table, and a downloadable PDF report make it useful for a quick check or for HVAC and equipment paperwork.
How to Use the Watts to BTU/hr Converter in 4 Steps
A complete watts-to-BTU/hr conversion takes a few seconds. Enter a wattage or tap a preset, choose your precision, and download a PDF report you can attach to an HVAC quote, equipment spec, or project file.
Enter the Power in Watts
Type any value in watts — a heater rating, an appliance nameplate, or a metric HVAC spec (multiply kW by 1,000 first, so 3.5 kW = 3,500 W). The calculator handles everything from a light bulb to a large electric furnace, and updates on every keystroke.
Or Tap a Quick Preset
Common ratings are one tap away: 500, 750, 1,000, 1,500, and 2,000 W, plus 3,517 W (1 ton of cooling). Each chip shows its BTU/hr value, so you can read the answer before you click. The active preset stays highlighted, and typing a matching value re-selects it automatically.
Set Decimal Precision
Use the input or slider to pick 0 to 8 decimal places (the default is 4). Whole BTU/hr values are plenty for heater and AC sizing, since equipment is sold in round sizes; more decimals suit engineering and technical records.
Review & Download PDF
See your power in BTU/hr, kilowatts, tons-and-BTU/hr, watts, refrigeration tons, horsepower, metric horsepower, and kcal/hr, plus a chart comparing the numbers. Click Download PDF for a two-page branded report with every conversion, the chart, and a highlighted reference table.
Why 1 Watt = 3.412142 BTU/hr
A watt is the SI unit of power: one joule per second. Over one hour, a 1 W load uses 3,600 joules. The British thermal unit is the heat needed to raise one pound of water by one degree Fahrenheit, and the International Table BTU used in this calculator is fixed at 1,055.05585262 joules. Dividing the two gives 1 W = 3.412142 BTU/hr — or 3,412.14 BTU/hr per kilowatt.
The refrigeration ton, still the standard size unit for US air conditioners and heat pumps, is defined as 12,000 BTU/hr — historically the rate of cooling from melting one short ton of ice over 24 hours. That’s about 3,516.85 W. The calculator uses these defined constants internally, so there is no rounding drift between units.
Power vs energy — and heat moved vs electricity used
Watts and BTU/hr are both rates (power). They’re different from BTU and kWh, which are amounts (energy). Two distinctions trip people up:
- Power vs energy — a 1,500 W heater produces 5,118 BTU/hr. Run it for 3 hours and it uses 4.5 kWh of electricity and delivers about 15,355 BTU of heat. Energy = power × time.
- Heaters — electric resistance heaters turn essentially all their wattage into heat, so watts × 3.412 is their heat output in BTU/hr.
- Air conditioners and heat pumps — their BTU/hr rating is heat moved, not electricity used. A 12,000 BTU/hr AC might draw only about 1,000 W, because it pumps heat rather than creating it.
That last point matters most: converting an air conditioner’s electrical wattage to BTU/hr gives the heat equivalent of the electricity, not its cooling capacity. For total energy over time, use our BTU to kWh Converter instead.
What the Watts to BTU/hr Converter Calculates
More than a single BTU/hr figure — the tool gives you a complete power breakdown across electrical, HVAC, mechanical, and metric units, formatted for heater sizing, AC specs, equipment sheets, or reports.
BTU per Hour (Hero Result)
The headline result multiplies your watts by 3.412142 to give BTU/hr, the unit used on US furnaces, heaters, air conditioners, and room-sizing charts, with a summary line beneath it that also gives kilowatts and the tons-and-BTU/hr split.
Kilowatts
Kilowatts (W ÷ 1,000) are how metric HVAC specs, electric furnaces, water heaters, and solar or generator ratings are written. Having kW beside BTU/hr lets you match an international spec sheet at a glance.
Tons & BTU/hr (Composite)
Larger results are split into whole refrigeration tons plus leftover BTU/hr — 5,000 W becomes 1 ton 5,061 BTU/hr. That mirrors how AC and heat-pump capacities are sold, so you can see which size class a load falls into.
Refrigeration Tons
Refrigeration tons (BTU/hr ÷ 12,000) express the result the way HVAC contractors size air conditioners and heat pumps — useful for checking a metric kW spec or a heat load against a 1-, 2-, 3-, or 5-ton system.
Horsepower, PS & kcal/hr
Mechanical horsepower (745.7 W), metric horsepower or PS (735.5 W), and kilocalories per hour round out the list — handy for motors, pumps, compressors, and older or international equipment ratings.
Chart, Reference Table & PDF
A log-scale bar chart compares your value in watts, BTU/hr, kcal/hr, kW, and tons so very different magnitudes fit on one view. A reference table of common heater and HVAC ratings highlights your input when it matches, and the two-page PDF bundles everything for sharing or record-keeping.
Watts to BTU/hr Conversion Chart — Common Values
Bookmark this page or screenshot the table below for instant reference. Every value uses the IT BTU (1 W = 3.412142 BTU/hr) and 1 ton = 12,000 BTU/hr, rounded to two decimals for BTU/hr and four for tons. Tonnage rows describe heat-moving capacity, not electrical draw; appliance examples are typical ratings.
| Watts | BTU/hr | Kilowatts | Tons | Common Use |
|---|---|---|---|---|
| 100 W | 341.21 BTU/hr | 0.100 kW | 0.0284 | Old incandescent bulb |
| 500 W | 1,706.07 BTU/hr | 0.500 kW | 0.1422 | Gaming PC under load (typical) |
| 750 W | 2,559.11 BTU/hr | 0.750 kW | 0.2133 | Space heater, low setting |
| 1,000 W | 3,412.14 BTU/hr | 1.000 kW | 0.2843 | Exactly 1 kW |
| 1,500 W | 5,118.21 BTU/hr | 1.500 kW | 0.4265 | Plug-in space heater, high setting |
| 2,000 W | 6,824.28 BTU/hr | 2.000 kW | 0.5687 | Hardwired wall or baseboard heater |
| 3,516.85 W | 12,000.00 BTU/hr | 3.517 kW | 1.0000 | 1 ton of cooling capacity |
| 5,000 W | 17,060.71 BTU/hr | 5.000 kW | 1.4217 | 5 kW electric furnace element |
| 7,033.71 W | 24,000.00 BTU/hr | 7.034 kW | 2.0000 | 2-ton AC or heat pump capacity |
| 10,000 W | 34,121.42 BTU/hr | 10.000 kW | 2.8435 | 10 kW electric furnace |
| 10,550.56 W | 36,000.00 BTU/hr | 10.551 kW | 3.0000 | 3-ton AC or heat pump capacity |
| 15,000 W | 51,182.12 BTU/hr | 15.000 kW | 4.2652 | 15 kW electric furnace |
| 17,584.26 W | 60,000.00 BTU/hr | 17.584 kW | 5.0000 | 5-ton AC or heat pump capacity |
| 20,000 W | 68,242.83 BTU/hr | 20.000 kW | 5.6869 | Large electric furnace or tankless water heater |
How to Use Watts and BTU/hr for Heating and Cooling
The most common reasons people convert watts to BTU/hr are to size an electric heater, to read a metric heat-pump spec in familiar US terms, and to work out how much heat electronics add to a room. Each one needs the conversion — and a clear idea of whether the watts describe heat produced, heat moved, or electricity used.
The manual calculation
Step 1: Make sure the rating is in watts (multiply kW by 1,000). Step 2: Multiply by 3.412142 for BTU/hr. Step 3: Divide by 12,000 to express it in tons. For a mini-split whose metric spec sheet lists 3.5 kW of cooling capacity:
3,500 W × 3.412142 = 11,942.50 BTU/hr
11,942.50 ÷ 12,000 = 0.9952 ton
Result: about 11,940 BTU/hr — a 12,000 BTU/hr (1-ton) class unit
Enter the wattage into the calculator and it does all three steps at once: the hero result shows BTU/hr, the kW line matches the spec sheet, and the refrigeration-tons line places the unit in its size class. Remember this is cooling capacity; the unit’s electrical draw is a separate, smaller number on the same spec sheet.
Heat from electricity and efficiency ratios
How watts relate to BTU/hr depends on what the equipment does with the electricity:
- Resistance heat (space heaters, baseboards, electric furnaces): heat out = watts in. A 1,500 W heater gives 5,118 BTU/hr.
- Electronics and lighting: nearly all their wattage ends up as heat in the room. 1,000 W of equipment adds about 3,412 BTU/hr of cooling load.
- Air conditioners and heat pumps: EER = BTU/hr of capacity ÷ watts of input. A 12,000 BTU/hr unit with an EER of 12 draws about 1,000 W.
- COP compares output and input in the same unit: COP = EER ÷ 3.412, so an EER of 12 is a COP of about 3.5.
Watts to BTU/hr — Key Conversion Numbers
The Watts to BTU/hr Converter Is Built For You If…
Whether you’re choosing a space heater, reading a heat-pump spec sheet, or cooling a hot home office — this calculator gives you the exact answer in seconds, with a report you can save and share.
Homeowners & Renters
Heaters & room comfortSpace heaters and baseboard heaters are sold by watts, while room-sizing guides and furnaces use BTU/hr. Converting helps you pick a heater that can actually warm the room, compare it with a portable AC or mini-split, and understand what your equipment is doing.
- Every 1,500 W heater gives the same 5,118 BTU/hr
- Rough guide: about 10 W per sq ft of room
- AC wattage is not its cooling capacity
- Check a circuit’s limits before adding heaters
HVAC Pros & Electricians
Specs, loads & circuitsContractors move between metric kW ratings on imported heat pumps, BTU/hr and tons on US equipment, and watts for electric heat and circuit loads. An exact converter with a printable report keeps proposals, load sheets, and customer explanations consistent.
- 1 ton = 12,000 BTU/hr ≈ 3.517 kW
- EER = BTU/hr ÷ W; COP = EER ÷ 3.412
- Label capacity and electrical input separately
- Attach the PDF to show the factor used
Home Offices, Workshops & Tech Setups
Equipment heat loadsComputers, servers, lighting, and shop tools turn nearly all their electricity into heat. Adding up their wattage and converting to BTU/hr tells you how much extra cooling a home office, media room, garage workshop, or equipment closet needs.
- Add up actual running watts, not power-supply ratings
- 1,000 W of equipment ≈ 3,412 BTU/hr of heat
- 3,000 W of gear ≈ 10,236 BTU/hr — nearly a ton
- Include people and sunlight in the total load
7 Tips for Accurate Watts to BTU/hr Conversions
The conversion is fixed, but the ratings you feed into it are easy to misread. Most mistakes come from mixing power with energy, confusing capacity with electrical draw, and using the wrong wattage figure. These rules keep every conversion trustworthy.
Keep Power and Energy Separate
Watts and BTU/hr are rates; kWh and BTU are totals. Multiply power by hours of use to get energy. A 1,500 W heater running 4 hours uses 6 kWh and delivers about 20,473 BTU.
Capacity Is Not Electrical Draw
An AC or heat pump’s BTU/hr or kW capacity is heat moved; its electrical watts are what it draws. Divide capacity in BTU/hr by the EER to estimate electrical watts — don’t convert one into the other.
Resistance Heat Is Always 1:1
Every watt of electric resistance heat gives 3.412 BTU/hr, regardless of heater style. Marketing claims aside, two 1,500 W heaters produce the same heat — only a heat pump can deliver more heat than the electricity it uses.
Convert kW Specs Before Comparing
Mini-splits and heat pumps from international brands often list capacity in kW. Multiply by 3,412.14 for BTU/hr: 2.5 kW ≈ 8,530 BTU/hr, 3.5 kW ≈ 11,942 BTU/hr, and 7 kW ≈ 23,885 BTU/hr.
Use Real Running Watts
Use the nameplate or measured running wattage, not the breaker size or a power supply’s maximum rating. A 750 W computer power supply rarely draws 750 W, and overestimating heat loads leads to oversized cooling.
Count Every Heat Source
When sizing cooling for a room, add up electronics, lighting, appliances, and occupants — then convert the total to BTU/hr. Sunlit windows and poor insulation add more, which is why professionals use a full load calculation.
Memorize Three Anchors for Mental Math
1 W ≈ 3.4 BTU/hr. 1 kW ≈ 3,412 BTU/hr. 1 ton = 12,000 BTU/hr ≈ 3.5 kW. With these you can sanity-check any spec in your head — a 1,500 W heater is about 5,100 BTU/hr, and a 5 kW heat strip is about 17,000 BTU/hr.
Watts to BTU/hr Converter — Frequently Asked Questions
Everything you need to know about converting watts to BTU per hour, how power differs from energy, and how to apply this calculator to heaters, air conditioners, heat pumps, and equipment heat loads.
One watt equals about 3.41214 BTU per hour. A watt is one joule per second, so one watt delivers 3,600 joules in an hour. Dividing by the International Table BTU of 1,055.05585262 joules gives 3,600 ÷ 1,055.05585262 = 3.412142 BTU/hr. One kilowatt is therefore about 3,412.14 BTU/hr.
Multiply watts by 3.412142: BTU/hr = W × 3.412142. For example, 1,000 W × 3.412142 = 3,412.14 BTU/hr, 1,500 W = 5,118.21 BTU/hr, and 5,000 W = 17,060.71 BTU/hr. To go from BTU/hr back to watts, divide by 3.412142, or multiply by 0.29307107.
Multiply BTU/hr by 0.29307107 (the same as dividing by 3.412142). For example: 5,000 BTU/hr = 1,465.36 W, 8,000 BTU/hr = 2,344.57 W, 12,000 BTU/hr = 3,516.85 W, 24,000 BTU/hr = 7,033.71 W, and 60,000 BTU/hr = 17,584.26 W. This converter takes watts as its input; to check a result, enter the wattage you calculated and confirm the BTU/hr result matches.
Watts and BTU per hour are both units of power — how fast energy is used or heat is moved. BTU and kilowatt-hours are units of energy — how much is used in total. Energy equals power multiplied by time. A 1,500 W heater produces 5,118 BTU/hr; running for 3 hours, it uses 4.5 kWh of electricity and delivers about 15,355 BTU of heat.
A 1,500 W electric space heater produces about 5,118 BTU per hour. Electric resistance heaters turn essentially all of the electricity they use into heat, so every 1,500 W heater — ceramic, oil-filled, or infrared — gives the same total heat output. They differ in how they spread that heat, not in how much they produce.
A common rule of thumb is about 10 watts per square foot for a room with average insulation and 8-foot ceilings. A 150 sq ft room needs roughly 1,500 W, or about 5,100 BTU/hr. Cold climates, high ceilings, large windows, or poor insulation can raise that considerably, so treat the rule as a starting point, not a sizing calculation.
No. An air conditioner’s BTU/hr rating is its cooling capacity — how much heat it removes — while its wattage is the electricity it draws. Because it moves heat rather than creating it, a 12,000 BTU/hr unit with an EER of 12 draws only about 1,000 W. Converting that 1,000 W to BTU/hr gives 3,412 BTU/hr, which is the heat equivalent of the electricity used, not the cooling delivered.
EER (energy efficiency ratio) is cooling output in BTU/hr divided by electrical input in watts. COP (coefficient of performance) is output divided by input in the same units, so COP = EER ÷ 3.412. An EER of 12 equals a COP of about 3.52, meaning the unit moves about 3.5 watts of heat for every watt of electricity it uses.
One refrigeration ton is 12,000 BTU/hr, or about 3,516.85 W (3.517 kW) of cooling capacity. A 2-ton system is 24,000 BTU/hr (about 7,033.71 W), a 3-ton system is 36,000 BTU/hr (about 10,550.56 W), and a 5-ton system is 60,000 BTU/hr (about 17,584.26 W). These are heat-moving capacities, not electrical draw.
Nearly all the electricity used by electronics indoors ends up as heat, at 3.412 BTU/hr per watt. A gaming PC drawing 500 W adds about 1,706 BTU/hr, and 3,000 W of equipment in a server closet adds about 10,236 BTU/hr — close to a ton of cooling. Include these loads when sizing air conditioning for home offices, media rooms, and equipment closets.
One mechanical horsepower is about 745.7 W, or 2,544.43 BTU/hr. One metric horsepower (PS) is 735.49875 W, or about 2,509.63 BTU/hr. One watt equals about 0.8604 kilocalories per hour, and one kilocalorie per hour is about 1.163 W.
The converter uses defined constants: 1 BTU (IT) = 1,055.05585262 J, so 1 W = 3.412141633 BTU/hr; 1 refrigeration ton = 12,000 BTU/hr; 1 hp = 745.699871582 W; 1 PS = 735.49875 W; and 1 kcal = 4,184 J. Calculations use double-precision floating-point arithmetic, accurate to about 15 significant digits. In practice, accuracy is limited by the wattage rating you start with and by real operating conditions, not by the conversion.
Accuracy note: The HomeExpertly Watts to BTU/hr Converter uses the International Table BTU: 1 BTU = 1,055.05585262 joules, so 1 watt = 3.412141633 BTU per hour, together with 1 refrigeration ton = 12,000 BTU/hr, 1 mechanical horsepower = 745.699871582 W, 1 metric horsepower (PS) = 735.49875 W, and 1 kilocalorie = 4,184 joules. All calculations are mathematically precise to the precision displayed. However, results are for informational and reference purposes only. An air conditioner’s or heat pump’s BTU/hr or kW rating describes heat moved, not electricity used, and actual performance depends on efficiency ratings (EER, SEER, COP, HSPF), outdoor conditions, installation, and usage. Room-sizing rules of thumb, appliance wattages, and other examples on this page are typical figures that vary by product, climate, and home. For applications where power figures are critical — including but not limited to HVAC sizing and load calculations, equipment selection, electrical circuit and breaker sizing, generator or solar sizing, or contract pricing — always verify figures independently using manufacturer specifications, a proper load calculation, applicable electrical codes, and a qualified HVAC professional or licensed electrician. HomeExpertly is not responsible for any consequences arising from the use of these conversions, including but not limited to undersized or oversized equipment, overloaded circuits, unexpected energy costs, or equipment damage.