How accurate are BAC calculators? What a study of 36 found
Online BAC calculators can return tidy numbers, but the neatness of a result says nothing about how well it represents a person. A 2026 study compared 36 calculators with reference values and found that, on average, the calculators returned values 39-49% higher than those references. The finding is important, and its limits matter just as much.
What the researchers tested
Stragierowicz and colleagues evaluated 36 online calculators against reference values from eight women and eight men, under fasted and post-meal conditions. The calculators were in Polish and English. The researchers reported that few calculators correlated with the reference values. BACscan, Aisko and website no. 3 were comparable under certain conditions.
The average difference is not a correction factor that can be applied to every calculator or every person. The comparison describes those calculators and those study conditions. A result that is higher on average does not tell us how a specific calculator would perform for an individual in a different setting.
The sample was small
The reference group included only 16 participants. That is a substantial limitation when interpreting results meant to speak to a broad population. The survey involved a larger group, but it does not expand the physiological reference sample used for comparison. The study covered Polish- and English-language calculators, so its findings should not automatically be generalized to every calculator available in other languages or markets.
Most importantly for this post, the study did not test CheersCount. It gives no basis for claiming that CheersCount is more accurate, or for assigning it any result from this comparison.
Why estimates vary
A calculator has to turn reported drinks into a model of absorption, distribution and elimination. Each step involves assumptions. The amount and strength of a drink may be entered imprecisely, and a model may simplify how quickly drinks are absorbed or how alcohol is distributed and eliminated.
Food is one relevant variable: it can slow gastric emptying and alter the timing and height of the resulting curve. Individual physiology and the inputs available to a model also matter. No online calculation can see all of those factors as they unfold in a particular body.
For that reason, estimates from population models can differ from an individual's result by roughly ±20-30%. That uncertainty is not a promise that every estimate falls within those bounds. It is a reminder that a calculated value is not a direct observation.
What to take from the comparison
The study is a useful check on how easily a calculator can present a precise-looking value without demonstrating close agreement with reference data. It also shows why comparisons need to name the reference group, conditions and limits, rather than reducing results to a universal score for all calculators.
If you use a BAC model, treat its output as an educational estimate, not a measurement or an exact account of an individual response. The method, the entered information and the real circumstances all affect what the number can tell you.
Frequently asked questions
How accurate are online BAC calculators?
It varies by calculator and circumstances. In a 2026 study, average values from 36 online calculators exceeded the study reference values by 39-49%, and only a few calculators correlated with the references. The result is not an individual accuracy guarantee.
What did the 2026 study actually compare?
Researchers compared 36 calculators with reference values based on eight women and eight men in fasted and post-meal conditions. They tested Polish and English-language calculators. The study did not test CheersCount.
Why can a BAC estimate differ from a person’s actual result?
A calculation depends on reported drink amounts and assumptions about absorption, distribution and elimination. Food changes absorption, and individual physiology and model choices also matter. A population model cannot observe all of those factors in a particular person.
Should I treat an estimated BAC as a measured value?
No. An estimated BAC is educational information, not a measurement. Individual results can vary by roughly ±20-30% from a population model, so a displayed value should not be treated as exact.
See the assumptions and try the BAC curve calculator. CheersCount presents a modelled estimate with an uncertainty band, not a measurement.
Source
Stragierowicz, J. et al. (2026). International Journal of Occupational Medicine and Environmental Health 39(3):245-269. DOI: 10.13075/ijomeh.1896.02802. Full text in PubMed Central.
BAC estimates are educational information, not measurements. Individual variation and model limitations mean a calculated result should never be treated as exact.