ARRGH! Well part of the discrepancy is my memory. I incorrectly recalled the 1.4 gram to tsp relationship, but in fact now that I check my reference sources, 1.4 g of metabisulphite is what 1/4 tsp weighs.
Sorry about that!
Re-doing the calculation, and realizing that 1.4 g per 1/4 tsp translates to 5.6 g per tsp, 5.6 g/tsp / .44 g/tablet means one tsp of metabisulphite powder is roughly equivalent to 12-1/2 tablets (that's for potassium meta, the equivalence for sodium meta is slightly different). That reduces the discrepancy a bit. All these conversions, and my inability to do arithmetic without resorting to a calculator, is one of the reasons why I prefer to work only in grams. :icon_scratch: