From NIST (et.al.) sources.  This is a list of conversion factors to convert Units of Volume.  The factors in this table convert the Units to a system reference Unit of cubic meters.  The conversions can be used to convert from or to the Units defined.  For example,  to convert from acre-feet to cubic meters, you would Multiply by the factor in this Table.  To convert from cubic meters to acre-feet (or other) use the factor in the Table as a divisor.

Notes

This data was gathered from the NIST appendix B document for units.  This table of Volume conversion is standardized to contain the Factor to convert to cubic meters.  

All units can be converted between other compatible units by converting the Units first to cubic meters and then again to the desired Unit result.  For example to convert acre-feet to gallons,  first use the conversion from acre-feet to cubic meters, and then apply the conversion from cubic meters to gallons.