Introduction Package quantity refers to the number of cigarettes or amount of other tobacco product in a package. Many countries restrict minimum cigarette package quantities to avoid low-cost packs that may lower barriers to youth smoking.

Methods We reviewed Truth Tobacco Industry Documents to understand tobacco companies’ rationales for introducing new package quantities, including companies’ expectations and research regarding how package quantity may influence consumer behaviour. A snowball sampling method (phase 1), a static search string (phase 2) and a follow-up snowball search (phase 3) identified 216 documents, mostly from the 1980s and 1990s, concerning cigarettes (200), roll-your-own tobacco (9), smokeless tobacco (6) and ‘smokeless cigarettes’ (1).

Results Companies introduced small and large packages to motivate brand-switching and continued use among current users when faced with low market share or threats such as tax-induced price increases or competitors’ use of price promotions. Companies developed and evaluated package quantities for specific brands and consumer segments. Large packages offered value-for-money and matched long-term, heavy users’ consumption rates. Small packages were cheaper, matched consumption rates of newer and lighter users, and increased products’ novelty, ease of carrying and perceived freshness. Some users also preferred small packages as a way to try to limit consumption or quit.

Conclusion Industry documents speculated about many potential effects of package quantity on appeal and use, depending on brand and consumer segment. The search was non-exhaustive, and we could not assess the quality of much of the research or other information on which the documents relied.