Calculator
What the BAC Calculator does
BAC Calculator: calculates Estimated BAC %, Impairment Level and Safety note from Body Weight, Sex and Standard Drinks. Example: body weight 70 kg, sex Male and standard drinks 2 gives estimated BAC % 0.0288.
The inputs are Body Weight, Sex, Standard Drinks and Hours Since Started Drinking; the output is Estimated BAC %, Impairment Level and Safety note. There is no submit step; the numbers move as you adjust them.
It is mostly used by anyone curious about a reading. Population formulas give you a starting point, not a verdict about your body.
Nothing leaves the tab. You can watch your browser network panel while you use it and see for yourself.
The field reference, the method and a worked example using the default inputs follow the tool itself.
What do the BAC Calculator fields mean?
The BAC Calculator uses 4 inputs. The starting figures are ordinary, not edge cases, so they make a sensible baseline.
| Field | What to enter | Default |
|---|---|---|
| Body Weight | measured in kg; accepts 40 to 200 | 70 |
| Sex | choose from Male or Female | Male |
| Standard Drinks | accepts 0 to 30 | 2 |
| Hours Since Started Drinking | accepts 0 to 24 | 2 |
How does the BAC Calculator work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same calculation.
If something is off you are told which field, not given a generic failure.
Worked example
These are the values the BAC Calculator loads by default, and the result it produces from them. The defaults produce the result shown here; change any of them and the answer moves.
| Body Weight | 70 kg |
|---|---|
| Sex | Male |
| Standard Drinks | 2 |
| Hours Since Started Drinking | 2 |
| Estimated BAC % | 0.0288 |
|---|---|
| Impairment Level | Impaired possible |
| Safety note | Estimated BAC ≈ 0.029%. Impaired possible. Never drive after drinking: this is only a rough Widmark estimate. |
How to use it
- Key in Body Weight in kg (40 to 200).
- Pick a value for Sex: the options are Male or Female.
- Type Standard Drinks (0 to 30).
- Enter Hours Since Started Drinking (0 to 24).
- There is nothing to click. The answer keeps pace with your edits.
- Read Estimated BAC %, Impairment Level and Safety note in the results panel.
- If you need a record, Copy Link saves the inputs and Print produces a clean page.
What this tool does not do
- Body composition, ethnicity and age all shift what a "normal" result means for an individual.
- Population-level formulas cannot account for medical conditions, medication or pregnancy.
- Where a standard has revisions, the version used is the one named in the method section.
- A plausible-looking answer from the wrong input is still the wrong answer: verify the fields first.
Frequently asked questions
Enter Body Weight in kg. Each field states its unit next to the input, and outputs are labelled the same way.
Body Weight accepts 40 to 200 kg. The range is enforced before the calculation runs, so a bad entry never reaches the formula.
With the values loaded when the page opens, estimated BAC % comes out as 0.0288. Edit any input and that figure moves with it.
No. Disconnect from the internet and it still works; that is the simplest proof there is no server call.
No cost and no account. Use it as often as you like.
It is a screening estimate, not a diagnosis. The formulas are standard, but they describe averages and you are not an average. Use it as a starting point for a conversation with a professional.