How many kJ is 20 BTU?
20 BTU = 21.1011 kJ
It is 21.1011 kJ, so saying 21 kJ is fine — rounding is within 0.5%.
And how many BTU is 20 kJ?
20 kJ = 18.9563 BTU
Formula: kJ = BTU × 1.055056
BTU to kJ around this value
2 BTU2.1101kJ
4 BTU4.2202kJ
6 BTU6.3303kJ
8 BTU8.4404kJ
10 BTU10.5506kJ
12 BTU12.6607kJ
14 BTU14.7708kJ
16 BTU16.8809kJ
18 BTU18.991kJ
20 BTU21.1011kJ
22 BTU23.2112kJ
24 BTU25.3213kJ
26 BTU27.4315kJ
28 BTU29.5416kJ
30 BTU31.6517kJ
32 BTU33.7618kJ
34 BTU35.8719kJ
36 BTU37.982kJ
38 BTU40.0921kJ
40 BTU42.2022kJ