Pack Years Calculator
Determine Your Smoking Risks

Pack years is the measurement used to determine lifetime tobacco exposure.

The smoking facts show that the harmful effects of cigarettes and smoking related diseases are more likely to occur with a higher exposure level.

The effects of cigarettes and smoking risks increase with the length and dose of tobacco exposure. Scientists calculate this measurement and then examine the cause and risk relationship between the amount smoked and the morbidity and mortality resulting from the many harmful effects of smoking.

A pack-year is smoking 20 cigarettes a day for one year. If you smoke ten cigarettes a day for six years You would have a 3 pack-year history.

Someone who has smoked 40 cigarettes daily for twenty years has a forty pack-year history.

The pack years measurement helps to quantify this risk by expressing both the number of cigarettes and the length of time spent smoking in a single measurement.

The measurement forms an international standard used to determine tobacco exposure.

It is used in two main ways.

1. as a smoking risk appraisal
2. to determine association or causality with specific smoking related diseases.

Appraisal of smoking risks

The documented harmful effects of cigarettes are plentiful.

In appraising your risk, the higher your pack-years number the greater the risk of developing smoking related diseases. With knowledge of your tobacco exposure your primary health care practitioner can determine if screening for smoking related diseases is necessary. If your smoking risks are quantified then your health care practitioner is better prepared to make decisions about other tests, screening procedures, and lifestyle counselling needed in order to protect your health.

Causality or association

Epidemiologists would use this measurement to determine if there was an association between disease and amount smoked. They would study two groups of people with higher or lower pack-year numbers and determine which group was more likely to develop smoking related diseases.

It should not be a surprise that all smoking risks increase with the number of cigarettes smoked and the length of time the body is exposed to all the chemicals in cigarettes.

Smoking Facts

Just a few smoking facts that illustrate the dose response relationship between tobacco exposure and smoking related diseases:

A higher pack-years number correlates with:

• a lower lung cancer survival rate. After a lung cancer diagnosis, never smokers live on average, at least 8 months longer that heavy smokers.


• an increased risk of going blind from age related macular degeneration with heavy tobacco use.


• a greater risk of admission to the intensive care unit if you are hospitalized for surgery


• increased risk for cancer of the tongue and oral cavity.

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