Comprehensive conversion tables for British thermal units. Other units include:- ergs foot-lbs gram-calories horsepower-hrs joules horsepower kilowatts watts

    
Btu Conversions.

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Put simply, one British Thermal Unit [Btu] is the amount of heat required to raise the temperature of 1 pound [ lb.] of water 1 degree Fahrenheit.
The Fifth International Conference on the Properties of Steam (London, July 1956) defined the International Table calorie as 4.1868 joule.
Therefore the exact conversion factor for the International Table British thermal unit (Btu) is 1.05505585262 kJ.
The thermochemical Btu is based on the thermochemical calorie which equals 4.184 kJ exactly.

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These units multiplied by ...... ..this factor will... ..convert to these units.
Btu
Btu
Btu
Btu
Btu (39 ºF)
Btu (59 ºF)
Btu (60 ºF)
Btu (international table)
Btu (thermochemical)
Btu
Btu
Btu
Btu /hr
Btu /hr
Btu /hr
Btu (int)/hr
Btu (thermo)/hr
Btu /min
Btu /min
Btu /min
Btu(thermo)/min
Btu (int)/sec
Btu (thermo)/sec
Btu (thermo) /sq. ft. min
Btu (int) /sq. ft. sec
Btu (thermo) /sq. ft. sec
Btu (thermo) /sq. in. sec
Btu (int) ft./hr sq.ft. ºF
Btu (thermo) ft./hr sq.ft. ºF
Btu (int) in /hr sq.ft. ºF
Btu (thermo) in./hr sq.ft. ºF
Btu (int) in /sec sq.ft. ºF
Btu (thermo) in./hr sq.ft. ºF
Btu (int) per cu. ft.
Btu (thermo) per cu. ft.
Btu (int) per ºF
Btu (thermo) per ºF
Btu (int) per ºRankine
Btu (thermo) per ºR
Btu (int /cu.ft. ºF
Btu (int) /hr sq.ft. ºF
Btu (thermo) /hr sq.ft. ºF
Btu (int) /sec sq.ft. ºF
Btu (thermo) /sec sq.ft. ºF
Btu (int) /lb
Btu (thermo) /lb
Btu (int) /lb
Btu (int) /lb
Btu (int) /lb. ºF
Btu (thermo) /lb. ºF
Btu (int) /lb. ºRankine
Btu (thermo) /lb. ºR
Btu (int) /sq. ft
Btu (thermo) /sq. ft.
Btu (int) /sq. ft. hr
Btu (thermo) /sq. ft. hr
~~~~
calorie, gram (mean)
~~~~
ergs
ergs/sec
~~~~
foot-pounds
foot-pounds/min
foot-pounds/sec
foot-pounds/sec
~~~~
gram-calories
gram-calories/sec
gram-calories
~~~~
horsepower
horsepower (boiler)
horsepower-hrs
~~~~
joules
~~~~
kilogram-calories
kilogram-metres
kilowatts
kilowatt-hrs
~~~~
tons refrigeration
~~~~
watts
watts
watts (absolute)
watt-hours
1.06E+10
778.3
252
0.0003931
1059.67
1054.80
1054.68
1055.056
1054.350
0.252
107.5
0.0002928
0.2162
0.07
0.0003929
0.2930711
0.2928751
12.96
0.02356
0.01757
17.57250
1055.056
1054.350
189.1489
11356.53
11348.93
1.634246E+06
1.730735
1.729577
0.1442279
0.1441314
519.2204
518.8732
37258.95
37234.03
1899.101
1897.830
1899.101
1897.830
67066.07
5.678263
5.674466
20441.75
20428.08
2326
2324.444
0.64616
0.55498
4186.8
4184
4186.8
4184
11356.53
11348.93
3.154591
3.152481
~~~~
0.00396832
~~~~
9.48E-11
5.69E-06
~~~~
0.001286
0.001286
4.6263
0.07717
~~~~
0.0039683
14.286
9.30E-08
~~~~
42.44
33479
2547
~~~~
9.48E-04
~~~~
3.968
9.29E-03
56.92
3413
~~~~
12000
~~~~
3.4129
0.05688
0.056884
3.413
ergs
foot-lbs
gram-calories
horsepower-hrs
joules (J)
joules
joules
joules
joules
kilogram-calories
kilogram-metres
kilowatt-hrs
foot-pounds/sec
gram-cal/sec
horsepower-hrs
watts
watts
foot-lbs/sec
horsepower
kilowatts
watts
watts
watts
watts /sq. metre
watts /sq. metre
watts /sq. metre
watts /sq. metre
watt per metre kelvin
watt per metre kelvin
watt per metre kelvin
watt per metre kelvin
watt per metre kelvin
watt per metre kelvin
joule per cu. metre
joule per cu. metre
joule per kelvin
joule per kelvin
joule per kelvin
joule per kelvin
joule per cu. metre kelvin
watt per sq. metre kelvin
watt per sq. metre kelvin
watt per sq. metre kelvin
watt per sq. metre kelvin
joule per kg.
joule per kg.
watts per kilogram
kilocalorie per kilogram
joul per kg kelvin
joul per kg kelvin
joul per kg kelvin
joul per kg kelvin
joul per sq. metre
joul per sq. metre
watt per sq. metre
watt per sq. metre
~~~~
Btu (mean)
~~~~
Btu
Btu/min
~~~~
Btu
Btu/min
Btu/hr
Btu/min
~~~~
Btu
Btu/hr
Btu
~~~~
Btu/min
Btu/hr
Btu
~~~~
Btu
~~~~
Btu
Btu
Btu/min
Btu
~~~~
Btu per hour
~~~~
Btu/hr
Btu/min
Btu (mean)/min
Btu
These units multiplied by ...... ..this factor will... ..convert to these units.
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We have tried to be accurate with the above table but cannot be held responsible for in-accuracies.
Go back to first principals and double check your calculations if the result is 'mission critical'.
Even the brilliant brains at NASA have made a conversion error or two !

The scientific notation used in the factors column helps to reduce long numbers to a manageable width. E+01 means moving the decimal point one space to the right so 1.00E+01 is shorthand for 10, then 1.33E+00 stays at 1.33 and 1.33E-01 becomes 0.133. The format tends to be used when the figure gets longer so E+09 or E-09 cuts out a lot of noughts.

Example:-
Task: How many sq.rods in 10 acres.
From the tables: 1 acre = 160 sq.rods, so
10 acres x 160 = 1600 sq.rods
When you want to reverse the conversion,
divide by the factor viz.
1600 sq.rods/160 = 10 acres

Remember that you cannot create energy only convert it. Likewise, you will not find a conversion from pounds to metres - the basic units must remain the same - mass converted to mass, length converted to length, et al.

You won't usually find a conversion from kilograms to grams - the prefix 'kilo' means '1,000' so a kilogram is in fact 1,000 grams in the same way as a kilometer is 1,000 metres [or about 1,000 yards in 'old money']. I have put a few in the table because visitors have asked for them. More prefixes can be found on another table.

One handy metric link between units to remember is that 1 Litre [1000cc] of pure water weighs 1 kilogram.

If accuracy is critical beware of old versions of MS Excel which had problems rounding off numbers.

Metrication is a great help but has also created anomalies; I have seen pressure gauges changed from a commonly used psi to kg/cm.sq., bar, pascal, kPa and atmos but will no doubt move to a popular metric standard in a few decades.

More information on the SI System (Le Système International d'Unités) base units and definitions.