Estimate BAC with safety disclaimer.. Blood Alcohol Calculator is a free online tool from the ToolsRift Finance & Health Calculators collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.
Enter the number and size of drinks, your body weight, sex and time elapsed. The calculator applies the Widmark formula for an approximate BAC. Never drink and drive.
This tool uses the Widmark formula: BAC = (alcohol grams / (body weight × distribution ratio)) minus the alcohol metabolised over the time since drinking.
It is only a rough approximation. Actual BAC depends on food, metabolism, medication and health, so never rely on it to judge whether you are fit to drive.
The body clears alcohol at roughly 0.015 BAC per hour on average, but this varies by person. Only time reduces BAC — coffee and water do not speed it up.