I've had a drink, when can I drive again ?

[Nigel Worc's]

Serious question, as apart from the odd bottle of real ale on a summers evening, at home, I don't normally drink.

I'm in England, so sensible limits apply.

I've had five pints of black sheep bitter, with a meal, at a Christmas party over the course of an entire evening, the last one being at 22.30 hours.

I do feel impaired, but not pissed by any means.

When do the collective think I'll be below the limit again , roughly ?

[Mr Classic]

Completely out of your system by 1030 latest, if you started at 7 then out by 0630. Ok to drive from about 0500. These are just averages.



I think.

[Red Devil]

Nigel Worc's said:

When do the collective think I'll be below the limit again , roughly ?

That will depend on a number of factors. Don't know enough about you to provide the answer.

Using these tools will give you a reasonably close guide.
http://www.blacksheepbrewery.com/beers/black_sheep...
http://www.drinkdriving.org/drink_driving_informat...
http://www.nhs.uk/chq/Pages/853.aspx?CategoryID=87
http://www.nhs.uk/Tools/Pages/Alcohol-unit-calcula...

[Willy Nilly]

This is my issue with the drink drive laws.

We all know that if we do 71mph on an empty motorway we will leave a trail of devastation in are wake not since since WWII and have dial in front of us to tell us when the carnage is going to start. But with being 1mg over the drink drive limit, not only will the world end but you get a criminal record and treated like a leper for good measure, but you really have no idea if you are legal or not.

Don't drink and drive then, is the answer. Correct, not many people go on the lash then drive home, but what about tomorrow?

[bramley]

Move to Malawi. If you get caught drink-drinking here you pay £7.50 and the kind policeman lets you DRIVE away! Not that there are any police around on the roads at night...

[Helicopter123]

bramley said:

Move to Malawi. If you get caught drink-drinking here you pay £7.50 and the kind policeman lets you DRIVE away! Not that there are any police around on the roads at night...

Are you saying a society that allows people to drive pissed is a better place?

[bramley]

Helicopter123 said:

Are you saying a society that allows people to drive pissed is a better place?

Oh yes, I mean clearly this country can teach the rest of the world so much about road safety

[anonymous-user]

Get a breathalyser or don't drive at all the day after having a skinfull. The rate at which people process alcohol varies widely, although a unit an hour is the usual approximation your certainly can't rely on it.

[anonymous-user]

If you feel impaired, then you shouldn't drive, regardless of your bloody alcohol level. It's as simple as that.

When I learned to fly, my human performance text book said that from the time you start drinking it takes approximately 1 hour for each unit of alcohol to be processed by the body, plus one hour. So if you assume that a typical pint of ale contains 2 units per pint (you'll need to check the actual figures for what you were drinking), and that you are of average size, then you're body should have processed all of the alcohol after 11 hours from your first drink. Of course you will be technically legal to drive a little while before that.

Of course, this isn't foolproof, but for a typical evening out like the one you describe, it's a pretty good guide and one i've always used.

[TooMany2cvs]

Inkyfingers said:

So if you assume that a typical pint of ale contains 2 units per pint (you'll need to check the actual figures for what you were drinking)

<points up to links earlier>
Black Sheep is 4.4%, so 4.4 units in one litre. A pint is 564ml, so 2.5 units. Five pints - 12.5 units.

[anonymous-user]

TooMany2cvs said:

<points up to links earlier>
Black Sheep is 4.4%, so 4.4 units in one litre. A pint is 564ml, so 2.5 units. Five pints - 12.5 units.

So you need approximately 13.5 hours from the first pint for the alcohol to leave the body. However, even that makes assumptions such as the rate of consumption.

As has been said, safest way is get a breathalyser and test yourself.

[allergictocheese]

TooMany2cvs said:

<points up to links earlier>
Black Sheep is 4.4%, so 4.4 units in one litre. A pint is 564ml, so 2.5 units. Five pints - 12.5 units.

That's the cask ale, which is generally rare on tap. I suspect Nigel was supping the Best Bitter, which is what you see in most pubs and is a more session friendly 3.8%

[rs1952]

TooMany2cvs said:

<points up to links earlier>
Black Sheep is 4.4%, so 4.4 units in one litre. A pint is 564ml, so 2.5 units. Five pints - 12.5 units.

[Pedant mode] One pint is 568ml [/pedant mode].

Not that this will change your calculations that much, though.

There seems to be a lot of confusion about what constitutes a "unit" of alcohol. It's 10ml. Simple as that. 10ml ethanol = 1 unit.

Therefore your pint of Black Sheep at 5% = 568ml of fluid, of which 24.992ml alcohol, = 2.5 units rounded to one decimal place.

Here are some other examples:

% proof Alcohol Units per pint
3.5-------19.88-----1.988
3.6-------20.448----2.0448
3.7-------21.016----2.1016
3.8-------21.584----2.1584
3.9-------22.152----2.2152
4.0-------22.72-----2.272
4.1-------23.288----2.3288
4.2-------23.856----2.3856
4.3-------24.424----2.4424
4.4-------24.992----2.4992
4.5-------25.56-----2.556
4.6-------26.128----2.6128
4.7-------26.696----2.6696
4.8-------27.264----2.7264
4.9-------27.832----2.7832

Large glass of wine (250ml):

% proof Alcohol Units per glass
10.5------26.25-----2.625
11--------27.5------2.75
11.5------28.75-----2.875
12--------30--------3
12.5------31.25-----3.125
13--------32.5------3.25

[TooMany2cvs]

rs1952][Pedant mode] One pint is 568ml [/pedant mode said:

.

<grin> Just testing, honest...

[quote]There seems to be a lot of confusion about what constitutes a "unit" of alcohol. It's 10ml. Simple as that. 10ml ethanol = 1 unit.

Therefore your pint of Black Sheep at 5% = 568ml of fluid, of which 24.992ml alcohol, = 2.5 units rounded to one decimal place.

The simpler way is to look at the ABV, and that's how many units in a litre. Then multiply by the number of litres you've actually drunk.

[7mike]

bramley said:

Helicopter123 said:

Are you saying a society that allows people to drive pissed is a better place?

Oh yes, I mean clearly this country can teach the rest of the world so much about road safety

http://internationaltransportforum.org/irtadpublic...

Perhaps you could elaborate on the rolled eyes smilie?
Looking at page two of this would suggest the answer to your comment is; yes. Quite a few of my colleagues do most of their work overseas these days. The founder of the largest post-test driver training organisation in the USA is an ex-met police driver.

[Halmyre]

Red Devil said:

That will depend on a number of factors. Don't know enough about you to provide the answer.

Using these tools will give you a reasonably close guide.
http://www.blacksheepbrewery.com/beers/black_sheep...
http://www.drinkdriving.org/drink_driving_informat...
http://www.nhs.uk/chq/Pages/853.aspx?CategoryID=87
http://www.nhs.uk/Tools/Pages/Alcohol-unit-calcula...

The drinkdriving link calculates blood alcohol count based on when you first had a drink - surely the time you had your last drink is just as relevant? Or am I missing something?

[anonymous-user]

Halmyre said:

The drinkdriving link calculates blood alcohol count based on when you first had a drink - surely the time you had your last drink is just as relevant? Or am I missing something?

The first unit takes 2 hours to be metabolised and each subsequent unit takes an hour. So the simple calc is, the time you can safely drive SHOULD be X+1 hours after the first drink where X is the total number of units consumed.

So if you drink 8 units in an hour, or in 8 hours the safe time is always 9 hours from the first drink.

The time of last drink is irrelevant as I understand it.

[Dr Jekyll]

garyhun said:

The first unit takes 2 hours to be metabolised and each subsequent unit takes an hour. So the simple calc is, the time you can safely drive SHOULD be X+1 hours after the first drink where X is the total number of units consumed.

So if you drink 8 units in an hour, or in 8 hours the safe time is always 9 hours from the first drink.

The time of last drink is irrelevant as I understand it.

So if you have 1 unit at Noon, then 7 more at 8PM, that's the same as having the other 7 units at 1PM? It seems to me there must be a difference.

[rs1952]

TooMany2cvs said:

rs1952][Pedant mode] One pint is 568ml [/pedant mode said:

.

<grin> Just testing, honest...

TooMany2cvs said:

rs1952 said:

There seems to be a lot of confusion about what constitutes a "unit" of alcohol. It's 10ml. Simple as that. 10ml ethanol = 1 unit.
Therefore your pint of Black Sheep at 5% = 568ml of fluid, of which 24.992ml alcohol, = 2.5 units rounded to one decimal place.

The simpler way is to look at the ABV, and that's how many units in a litre. Then multiply by the number of litres you've actually drunk.

My second to fourth line of my post was copied and pasted from one that appeared on PH back in 2005 that I kept for posterity, but that time they were taking about beer that was 5% proof. I edited the later calculation but forgot to edit the percentage against Black Sheep which, as Nigel as already mentioned, was 4.4%.

Just testing, honest

But I'm not sure that your way is any simpler than mine given that, if you're drinking in a pub, you'll be drinking by imperial measure and not metric. So then you need to know, and remember, how many pints there are in a litre to be able to do the calculation. When you've already possibly just had a skinful...

[Nigel Worc's]

Roughly 12 hours from my last drink is good enough for me chaps, I don't do it very often, hence the question, I wouldn't drive if I felt impaired anyway, alcohol related or not.

As long as I feel ok, legal is what I'm looking for, rather than zero.