INTRODUCTION
Despite the global fall in prevalence of tobacco smoking in the last three decades, the growth in population has increased the number of smokers from 0.99 billion in 1990 to an all‐time high of 1.14 billion in 2019 [The size of cigarette packs—the number of cigarettes in a single pack—is a potentially important but neglected tobacco control target [An increasing number of jurisdictions have set a minimum size of 20 cigarettes per pack to make cigarettes less affordable to young people, in accordance with the international recommendations under the WHO Framework Convention on Tobacco Control [Based on robust evidence from studies of food consumption [The causal nature of the association between pack size and cigarettes smoked per day remains uncertain. The aim of the current randomized controlled cross‐over trial is to assess the impact on cigarette consumption of using packs of 20 cigarettes compared to packs of 25 cigarettes.