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Blood Alcohol Content Calculator

Estimates BAC from drinks, body weight, sex and time elapsed using the Widmark formula.

Calculators Nothing uploaded No sign-up Free, unlimited
Calculators tool
10 g in the UK and Australia, 14 g in the US
Enter your figures and press Calculate.
In short Blood Alcohol Content Calculator is a free online tool on inputtesthub.com that estimates BAC from drinks, body weight, sex and time elapsed using the Widmark formula. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.

How to use the Blood Alcohol Content Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the Blood Alcohol Content Calculator

The Blood Alcohol Content Calculator estimates BAC from drinks, body weight, sex and time elapsed using the Widmark formula. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Understanding roughly how long alcohol stays in the system.
  • Educational and awareness contexts.
  • Seeing how much difference body weight makes.

The maths behind it

This tool uses the Widmark equation: BAC = alcohol in grams ÷ (body weight in grams × distribution ratio) × 100, minus roughly 0.015 per hour of elimination. Every intermediate value is shown on screen, so the result can be checked by hand.

This is an estimate only and must never be used to decide whether you are safe to drive. Real BAC varies with food, medication, liver function, hydration, drink strength and individual metabolism. The only safe amount before driving is none.

Frequently asked questions

Is the Blood Alcohol Content Calculator free, or is there a paid tier?
It is free, with no account, no trial and no daily cap. Every calculators tool on inputtesthub.com works the same way: open the page and use it.
Can you see what I put into this tool?
No. The Blood Alcohol Content Calculator runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
What is the equation behind the Blood Alcohol Content Calculator?
It uses the Widmark equation: BAC = alcohol in grams ÷ (body weight in grams × distribution ratio) × 100, minus roughly 0.015 per hour of elimination. The full working is printed under the result, so you can follow every step rather than trusting a black box.
When would I actually need the Blood Alcohol Content Calculator?
The most common reasons people reach for it: understanding roughly how long alcohol stays in the system. Educational and awareness contexts. Seeing how much difference body weight makes. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Any caveats I should know about?
This is an estimate only and must never be used to decide whether you are safe to drive. Real BAC varies with food, medication, liver function, hydration, drink strength and individual metabolism. The only safe amount before driving is none.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

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