Arrive Alive

How Much Is Too Much To Drink Before I Drive?

How Much is Too Much to drink before I drive?

People often ask how much can they drink before they go past the limit?

Here is a "basic" answer:

1 metric tot is 8,4 g of ethyl alcohol.

The average beer contains between 13 - 16 grams of ethyl alcohol.

One beer is therefore ± equivalent of a double eg brandy.

In trials all the participants (Male & Female students) exceeded the legal limit = 0,05g/dl after two beers.

According to the Widmark formula:

A = p x c x 10 x r
A = amount of alcohol in grams
p = mass of the person
x 10 = to convert promille ( parts per thousand) to g/dl or g/%
"r" = Widmark factor which is on average 0,7 for men and 0,6 for females.
c = blood alcohol level.

Blood alcohol level = A divided by p x r x 10.

As far as wine is concerned: It would depend on whether you are referring to fortified wine or not. (Fortified implying that alcohol had been added to the wine)

Usually on any bottle the % of alcohol is indicated. 10% would imply 10 grams/alcohol per 100 ml of wine. Then once again the Widmark formulae can be applied to get an estimation of expected blood alcohol level.

Many other factors determine the uptake of alcohol.

These factors include:

Volume, strength, type of dilutant ( eg Coke), type of meal, medication, previous operations, temp of drink, water content of organs, diffusion gradient, rate of blood flow, any GIT disease etc. The effects vary from person to person. No set pattern of behavior does exist. We do not wish to elaborate on all these factors. As you can probably deduct, there is not a simple answer to the question !!

It is important to understand that alcohol affects the cognitive functions of the intoxicated person. Driving is an action that requires good multitasking with the driver having to concentrate not only on steering the vehicle- but also road conditions, other vehicles and pedestrians, signs and traffic lights etc

Visitors to the Arrive Alive website often ask how many drinks they may have before they go on the road. This is a question we need to approach with caution. It is important to recognize that there are too many variables to provide an exact answer - and we can only provide a rough guide.

It is also important to recognize that this is only a guide to what might keep you within the legal limit.

If the question is “How many drinks may I have before my ability to drive is reduced?” - the answer would be NONE!


We would rather like to recommend that you DO NOT drink before you drive - and that you plan ahead and have a sober designated driver take you home!

We would like to share the guide provided by the Institute of Alcohol Studies:

The basic guideline in South Africa is that 2 drinks within 1 hour will put you on/over the legal limit so don’t drink more than this if you will be driving.

View: Alcohol and You - Institute of Alcohol Studies

Alcohol can also contribute towards inattentional blindness - the failure to detect unexpected salient objects that appear in the visual field of the intoxicated person.

Click Here for the International Study: Blind Drunk: The Effects of Alcohol on Inattentional Blindness

Study by: Seema L Clifasefi , Melanie K T Takarangi & Jonah S Bergman

To conclude - do not drink and drive!

View this Guide from South Africans Against Drunk Driving [SADD]

Also visit the following sections:

Drunk Driving and Road Safety

Alcohol, Drugs and Road Safety

Search Road Safety Articles

Latest Pages

Road Safety Tips For Easter 2018

Road Safety Tips For Easter 2018

1 Obey the rules of the road and carry your driver’s licence with you. 2 Plan the route to your holiday destination and allow enough time to reach the destination - taking into account many road works and delays along the route! 3 Check that your vehicle is in a roadworthy condition

Read More

Fleet Management / Logistics and Road Safety

Fleet Management  / Logistics and Road Safety

Background Information Fleet management is a term used to describe the management of any/all aspects relating to a company’s vehicle. This can include a range of functions, such as vehicle financing, vehicle maintenance, vehicle telematics (tracking and diagnostics of vehicles), driver management,

Read More

Hijack Prevention Guidelines

Hijack Prevention Guidelines

Introduction: It has become increasingly difficult to steal motor vehicles, with all the anti-theft devices, such as immobilisers, gear-locks, etc. These steps have resulted in a dramatic increase in vehicle hijackings. The hijacker has the element of surprise and this is a concern. The increasing

Read More

Protecting Yourself against Hijackings

Protecting Yourself against Hijackings

Amidst the increase in hijackings in South Africa, it is very important to know some of the following aspects: How do the hijackers operate? When am I most at risk? How do I avoid being hijacked? What do I do when confronted? HOW TO AVOID A HIJACK SITUATION Sterling work has been

Read More

Standard Bank and Fuel Cards, Fleet Cards and Safety from Fraud

Standard Bank and Fuel Cards, Fleet Cards and Safety from Fraud

What are the best measures from the side of the bank to combat fraud with a garage/ petrol card? A robust and state of the art fleet management system is key to assist customers to manage fleet expenses and combat fraud. In 2010 Standard Bank Fleet Management pioneered and led an industry initiative

Read More

Absa and Fuel Cards, Fleet Cards and Safety from Fraud

Absa and Fuel Cards, Fleet Cards and Safety from Fraud

Absa: General Comments Absa views financial crime in a very serious light and takes a zero-tolerance approach to all matters involving criminal conduct. We invest heavily in a comprehensive and robust suite of information protection measures and work closely with law enforcement agencies and banking

Read More

Load More Pages


View All