BAC to Weight Calculator

Enter BAC and Drink Details

Target BAC

Use 0.08 as decimal, or choose percent.

BAC Input Type

Drink Volume

Volume Unit

Alcohol Strength ABV %

Number of Drinks

Hours Since First Drink

Metabolism Rate

Common estimate is 0.015 BAC per hour.

Widmark Ratio

Custom Ratio

Decimal Places

Formula Used

The calculator rearranges a Widmark style estimate. It solves weight from alcohol amount, target BAC, ratio, and elapsed time.

Weight in pounds = pure alcohol ounces × 5.14 ÷ [Widmark ratio × (target BAC + metabolism rate × hours)]

Pure alcohol ounces = drink volume in ounces × ABV ÷ 100 × number of drinks

The constant 5.14 works with fluid ounces of alcohol and pounds of body weight. Metric volumes are first converted to fluid ounces.

How to Use This Calculator

Enter the target BAC. Choose decimal or percent format.
Enter one drink size, ABV percentage, and drink count.
Add hours since the first drink and the metabolism rate.
Select a Widmark ratio, or enter a custom ratio.
Press calculate. The result appears above the form.
Use the CSV or PDF button to save the estimate.

Example Data Table

Target BAC	Drink Pattern	Hours	Ratio	Estimated Weight
0.020	1 × 12 oz beer at 5%	0.5	0.73	153.60 lb / 69.67 kg
0.080	3 × 12 oz beer at 5%	1.5	0.73	123.65 lb / 56.09 kg
0.080	2 × 5 oz wine at 12%	1	0.66	98.37 lb / 44.62 kg
0.150	4 × 1.5 oz spirit at 40%	2	0.73	93.88 lb / 42.58 kg

About This BAC to Weight Tool

A BAC to weight calculator works backward from a target blood alcohol concentration. It estimates the body weight that could match a drink pattern, alcohol strength, elapsed time, and Widmark ratio. The result is only a planning estimate. Real BAC can vary because food, hydration, medicine, health, and drinking speed change absorption.

Why Reverse BAC Matters

Many calculators start with body weight and then estimate BAC. This page reverses that idea. It asks what body weight would fit the entered BAC after the chosen alcohol dose. This can help writers, teachers, safety teams, and students test examples. It can also show how strongly body size affects concentration.

What The Inputs Mean

The target BAC is entered as a decimal value, such as 0.08. Drink volume means one serving size. ABV means alcohol by volume. The number of drinks multiplies the serving. Hours since first drink reduce the active estimate through a metabolism rate. The Widmark ratio represents body water distribution.

Reading The Result

The main answer shows estimated weight in pounds and kilograms. It also lists pure alcohol ounces, standard drink count, adjusted BAC before elimination, and calculation steps. If the adjusted BAC becomes too low, the tool asks for stronger inputs. That protects the formula from impossible or misleading output.

Safe Use Notes

This calculator must not decide if anyone can drive, work, or pass a legal test. Breath devices, blood tests, local law, and personal biology are different. Always treat the answer as educational. Choose safer travel, avoid impaired tasks, and follow local rules. When health or legal risk exists, ask a qualified professional.

Exporting And Comparing

The export buttons keep the estimate easy to save. CSV is useful for spreadsheets and records. PDF is useful for simple reports. The example table gives common practice rows. Change one value at a time and compare the results. This makes the effect of ABV, serving size, time, and ratio easier to see. Higher drink strength raises pure alcohol. More elapsed time lowers the estimated remaining BAC. A smaller ratio can produce a lower estimated weight for the same BAC. Use these comparisons for learning, not permission. Keep clear notes with each saved estimate.

FAQs

What does this calculator estimate?

It estimates the body weight that could match a target BAC after a stated drink amount, alcohol strength, time period, and Widmark ratio.

Is this a legal BAC test?

No. It is only an educational estimate. Legal BAC depends on approved testing methods, local rules, timing, and individual biology.

What target BAC should I enter?

Enter a decimal like 0.08, or choose percent and enter 8. The form converts the selected format before calculating weight.

What is the Widmark ratio?

It represents alcohol distribution in body water. The calculator offers common average values and a custom field for learning examples.

Why does time affect the result?

Elapsed time reduces estimated BAC through the metabolism rate. The calculator adds that reduction back before solving the weight equation.

Can I use milliliters?

Yes. Choose milliliters in the volume unit field. The script converts milliliters to fluid ounces before applying the formula.

Why is my result unrealistic?

Very high BAC targets, tiny drink amounts, or unusual ratios can create unrealistic weights. Check units, ABV, drinks, and time.

Can I export the calculation?

Yes. After calculation, use the CSV button for spreadsheet data or the PDF button for a simple saved report.