Converter · 1 kW = 3,412 BTU/hr
kW to BTU/hr converter
Thermal power across unit systems — with tons, MBH, an EER/COP bridge, and the boiler nameplate trap explained. Type in any field; everything updates.
Last updated: October 2026
Converter · 1 kW = 3,412 BTU/hr
kW ↔ BTU/hr ↔ Tons ↔ MBH
Type in any field — all units update. EER/COP bridge for equipment comparison.
Quick presets
COP: — · kW/ton: —
kW to BTU/hr — the thermal bridge
1 watt = 1 joule/second exactly. 1 BTU (International Table) = 1,055.056 J. Therefore 1 BTU/hr = 1,055.056 ÷ 3,600 = 0.293071 W, and 1 kW = 3,412.14 BTU/hr. Memorize three numbers: 3,412 (kW→BTU/hr), 0.293 (BTU/hr→kW), 12,000 (BTU/hr per ton). A 10 kW heater = 34,121 BTU/hr ≈ 2.8 tons.
Tons, MBH, and the nameplate trap
1 ton of refrigeration = 12,000 BTU/hr = 3.517 kW (melting one ton of ice in 24 h). MBH = thousands of BTU/hr (400 MBH = 400,000 BTU/hr) — the US boiler convention. Boiler nameplates list input MBH (fuel rate) and output MBH (useful heat); the ratio is AFUE. Comparing a 400 MBH-input US boiler against a 100 kW-output European boiler requires converting output-to-output (99.6 kW vs 100 kW — equivalent machines), not input-to-output.
EER, COP, and kW/ton
EER (BTU/hr per watt) and COP (kW out per kW in) measure the same efficiency: COP = EER ÷ 3.412, and kW/ton = 12 ÷ EER. EER-12 = COP 3.52 = 1.0 kW/ton. Enter any EER above for the full bridge. For heat pumps, output = input × COP — a 5 kW-input unit at COP 4 delivers 20 kW of heat.
FAQ
Thermal conversion questions, answered
How many BTU/hr is 1 kW?
1 kW = 3,412 BTU/hr. Reverse: 1 BTU/hr = 0.000293 kW. A 10 kW heater outputs 34,121 BTU/hr — roughly a 2.8-ton heat pump.
What is a ton of refrigeration in kW?
1 ton = 12,000 BTU/hr = 3.517 kW. It comes from melting one ton of ice in 24 hours. A 5-ton rooftop = 60,000 BTU/hr = 17.6 kW.
How do I convert EER to COP?
COP = EER ÷ 3.412. An EER-12 unit has COP 3.52. For kW/ton: 12 ÷ EER. EER-12 = 1.0 kW/ton.
What is MBH on a boiler nameplate?
MBH = thousands of BTU/hr. A 400 MBH boiler burns 400,000 BTU/hr of fuel (input). At 85% AFUE it delivers 340 MBH of useful heat (output). Always compare output-to-output across US and European equipment.
Does this converter work offline?
Yes. FieldCalc is an installable PWA — after your first visit, this converter runs with zero signal. All math stays on your device.
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