How this calculator works
Daily consumption times elapsed days gives the cumulative cigarette count. Dividing by the retail pack size gives packs. Average rates may include fractions; a fractional total is an estimate rather than a claim that part of a cigarette was counted. A year uses 365.25 days and a month one twelfth of that, so enter days for an exact day count. Retail pack size affects pack counts but does not change the clinical definition of a pack-year, which uses 20 cigarettes per day. The result is an estimate for information only and is not medical advice.
Formula
Total cigarettes = cigarettes per day x days. Packs = cigarettes / cigarettes per pack. Days = total cigarettes / cigarettes per day.
Worked example
At 10 cigarettes a day for 30 days, the total is 300 cigarettes or 15 packs of 20. At 2 packs of 25 per day for 7 days, it is 350 cigarettes or 14 retail packs.
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Frequently asked questions
Can I use packs of 25?
Yes. Enter 25 as the retail pack size. Daily-pack and total-pack outputs then refer to those packs.
What if consumption changed?
Calculate each interval separately and add the cigarette totals, or enter a time-weighted daily average.
Is this a life-expectancy calculation?
No. It counts consumption. It does not estimate years of life lost, diagnosis or an individual cancer risk.