One cubic foot per minute is 1.6990107955 cubic metres per hour. CFM is the American air flow unit, and this conversion is what lets an American fan or air handler be compared with a European one.
About the units
Cubic feet per minute, always written CFM after the English words, is the standard air flow unit in American ventilation, compressed air and dust extraction. Cubic metres per hour is the European equivalent. The conversion combines the cubic foot of 0.028316846592 m³ with the sixty minutes in an hour, which is why the factor is close to 1.7 rather than to any round number. Note that compressed air specifications add a further complication: SCFM refers to standard conditions of temperature and pressure, and comparing it to a volumetric flow without those conditions stated is meaningless.
The exact factor
The derivation is 0.028316846592 × 60 = 1.69901079552 m³/h per CFM. Inverted, 1 m³/h is 0.588578 CFM. Reference points: a bathroom fan at 50 CFM is 85 m³/h; a kitchen range hood at 400 CFM is 680 m³/h; and a residential air handler at 1,200 CFM is 2,039 m³/h. In litres per second, 1 CFM is 0.4719 l/s, so a 50 CFM fan moves 23.6 l/s — the unit Nordic building regulations would specify it in.
Where you meet this conversion
Comparing American and European ventilation equipment, which is the whole reason this page exists. Fan curves, filter pressure drops and duct velocity tables are all in CFM in American documentation. Dust extraction and workshop ventilation equipment is frequently imported, and matching an American extractor to a European duct system requires the conversion. Compressed air tools are rated in CFM or SCFM while European compressors are rated in litres per minute or cubic metres per hour, and undersizing a compressor is the usual consequence of getting it wrong.