The scale-up of a microchannel reactor for Fischer-Tropsch (FT) synthesis has been demonstrated at multiple scales using four reactors with different lengths and number of channels. An FT catalyst provided by Oxford Catalysts, Ltd. was tested in single channel mieroreactors with catalyst bed length ranging from similar to 4 to similar to 62 cm. The same catalyst was also tested in a pilot reactor with 276 parallel process channels (similar to 17 cm in length). Equivalent process performance was observed across each scale as determined by the metrics of CO conversion, selectivity to byproduct, and the chain growth probability (alpha). The overall C5+ productivity for these reactors of disparate scales spanned several orders of magnitude ranging from similar to 0.004 gallons per day (GPD) to similar to 1.5 GPD. The operational flexibility of these microreactors was illustrated by varying syngas feed composition and flow sheet conditions (pressure, temperature, dilution, etc.). The elusive premise of numbering up microchannels has been demonstrated, enabling the scale-up of reactor capacity.