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The power figure in watts to express as heat.
For cooling load work, essentially all the electrical power drawn by lighting and equipment inside a space ends up as heat within it, so the wattage and the heat gain are effectively the same number in different units.
Heat equivalent
5,118 BTU/hr
Converted using an exact defined factor of 3.412141633127968 BTU/hr per W. Useful for internal gains, where wattage drawn inside a room becomes heat the cooling system has to remove.
- Conversion factor applied
- 3.41 BTU/hr per W
They open the calculator with your figures already in it
Watts to BTU/hr Calculator: 5,118 BTU/hr — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- 1 W = 3.412141633 BTU/h, from the definition 1 BTU/h = 0.29307107017222 W
- Sensible heat gain from equipment: for cooling load purposes, electrical input inside the conditioned space is treated as heat gain
Inputs used
- Power (W)
- 1500
Intermediate steps
- Conversion factor applied
- 3.41 BTU/hr per W
Confidence note: Converted using an exact defined factor of 3.412141633127968 BTU/hr per W. Useful for internal gains, where wattage drawn inside a room becomes heat the cooling system has to remove.
What this calculation does not cover
- This is a unit conversion, not a cooling load calculation. It converts the wattage you type and nothing else — solar gain through glazing, conduction through the envelope, infiltration and ventilation air are all outside it. The result is one line of an internal gains list, not a basis for selecting plant.
- No diversity or duty-cycle factor is applied. The figure is treated as drawn continuously, while nameplate ratings on motors, ovens, kitchen equipment and IT loads usually run well below the plate in service, so totalling connected wattage without a use factor overstates the gain.
- It cannot tell heat that stays in the room from heat that leaves it. A vented dryer, an extract-hooded appliance or a rack on a contained exhaust carries much of its own load out of the space, and only the portion released into the room belongs in the entry.
- The output is a single BTU/hr figure with no sensible and latent split, and no occupant gain. Equipment that evaporates water — cooking, humidifiers — puts part of its input into moisture rather than air temperature, and people are published per person as sensible and latent watts by activity level. Take both from a load table and keep them separate.
- The conversion does not know whether the watts entered are electrical input or thermal output. Enter a heat pump's or air conditioner's input power and the BTU/hr figure is the electricity it draws, not the heat it moves; those differ by the coefficient of performance.
Add the equipment this sizes
This result is a specification — 5,118 BTU/hr — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations2
- 1 W = 3.412141633 BTU/h, from the definition 1 BTU/h = 0.29307107017222 W
- Sensible heat gain from equipment: for cooling load purposes, electrical input inside the conditioned space is treated as heat gain
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Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
Cooling load work often starts with a list of what is plugged in: lighting circuits, servers, kitchen equipment, and the people in the room. Inside a conditioned space almost all of that electrical power ends up as heat, so the wattage total converts directly into a BTU per hour gain the plant has to remove. The exception worth remembering is any equipment that exhausts its heat outside the space — a vented dryer or an extract-hooded appliance moves much of its load out of the room, and counting it as an internal gain oversizes the system. Occupant load is not electrical at all and comes from published sensible and latent figures per person by activity, so add those separately rather than trying to express people in watts.