What is scale in?
Adding to a position you already hold by buying more, which blends your average cost across the entries.
Adding to a position you already hold by buying more, which blends your average cost across the entries.
Scale in, explained
Scaling in means buying more of something you already own rather than taking the whole position at once. Each add re-averages your cost — “Buy more” on a position records a scale-in, and the page tracks how many times you’ve added. Scaling out is the reverse: selling part of a position while keeping the rest.
A worked example
Bought 50 shares at $20, then 50 more at $24 → avg cost $22 across two scale-ins.
Where scale in shows up in a journal
A trading journal is where this stops being a definition and becomes your own number. sizeforzero computes it from the trades you import or log, alongside the rest of your analytics vocabulary, and every figure in the app carries an (i) that explains it in the same plain English you just read.