A thing I find helpful in cases like these is to switch to using SI units:

    : user@debian:~; units
    2529 units, 72 prefixes, 56 nonlinear units

    You have: 6673 million tonnes per year
    You want: Mg/s
            * 211.45913
            / 0.0047290463
    You have: 110000 pounds per hour
    You want: kg/s
            * 13.859767
            / 0.072151286

For some stupid reason, every field invents their own idiotic and idiosyncratic collection of slightly incompatible units: millibars, Torr, kilograms per square centimeter, or psi instead of Pascals; pounds per hour, metric tons per day, or metric tons per year instead of kilograms per second; quadrillion Btu per year, kilowatt-hours per month, or horsepower instead of watts; and so on. It's totally counterproductive and I wish people would stop.