Dial in a color on a test cup, then reproduce it exactly at full scale — or apply your colorant's stated percentage to any amount of resin. Either way it checks the total against the maximum load your product allows.
Pigment loads are usually specified by weight — grams are safest. Use the same unit your manufacturer's percentage refers to.
Batch amount is your mixed resin (or whatever base the percentage refers to). Load % comes from your colorant's label.
In percentage mode the colorant amount is simply your batch times the load percentage — 4% of 500 grams is 20 grams. In recipe mode every colorant weight from your test is multiplied by the ratio of the new batch to the test batch, so a batch seven and a half times larger uses seven and a half times each pigment. The recipe mode also totals the colorant and reports it as a percentage of the batch.
Color is far easier to reproduce by weight than by drops or scoops. Zero a scale, add resin, and note the weight; then add each pigment and record it. With those numbers the color scales perfectly to any size, which is why the recipe mode asks for weights rather than counts.
Colorant does not cure — it is carried by the resin — so past a point it interferes with the reaction and leaves the epoxy soft or tacky. That point differs by product and pigment, which is why this tool asks for your manufacturer's maximum rather than assuming one. Enter it and the result flags any mix that exceeds it.
Mica powders mostly affect appearance and are usually added lightly by eye; concentrated liquid pigments and pastes are strong and have the tightest maximum loads. Keep a separate tested recipe for each colorant and product combination rather than moving a percentage from one system to another.