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Alcohol and health

Cider and driving

How much cider can I drink and still drive?

In short

There is no answer to that question that CiderHQ or anyone else can give you. No calculation from units, body weight, time elapsed or how you feel establishes an individual’s blood alcohol concentration, and none of them establishes that you are safe to drive.

The legal limits differ within the United Kingdom: Scotland has a lower limit than England, Wales and Northern Ireland, and a driver who is under the limit in one is not necessarily under it in the other.

Impairment begins below every legal limit. The limits define an offence; they do not define a level at which driving is unaffected.

The limits, and where they differ

Scotland reduced its drink-drive limit in December 2014. The limit there is 50 milligrams of alcohol per 100 millilitres of blood, 22 microgrammes per 100 millilitres of breath, and 67 milligrams per 100 millilitres of urine.

In England, Wales and Northern Ireland the limit remains 80 milligrams per 100 millilitres of blood, 35 microgrammes per 100 millilitres of breath, and 107 milligrams per 100 millilitres of urine.

The practical significance for a driver is that crossing the border changes the legal position without anything changing in the vehicle or in the driver. A driver who is lawfully under the limit in Carlisle may be over it in Gretna.

Limits elsewhere differ again, and several European countries operate lower general limits and stricter limits for novice and professional drivers. Anyone driving in another jurisdiction should check that jurisdiction’s current rules with its own authority.

Drink-drive limits within the United Kingdom
JurisdictionBloodBreathUrine
Scotland50 mg / 100 ml22 µg / 100 ml67 mg / 100 ml
England80 mg / 100 ml35 µg / 100 ml107 mg / 100 ml
Wales80 mg / 100 ml35 µg / 100 ml107 mg / 100 ml
Northern Ireland80 mg / 100 ml35 µg / 100 ml107 mg / 100 ml
No calculation tells anyone they are safe to driveBlood alcohol concentration depends on body composition, sex, food, the rate of drinking, medication, liver function and individual metabolic rate. No units calculator, chart, app or rule of thumb converts drinks into a reliable blood alcohol figure for a specific person, and CiderHQ does not offer one. The only approach that reliably keeps a driver under any limit is not to drink before driving.

Why cider makes the estimate worse

The strength range is wide, and cider is often served without an ABV shown. A drinker who does not know whether they have had 4.5 per cent or 7.5 per cent cider cannot estimate their intake within a factor of nearly two.

Cider is served in beer measures. A pint of 7.5 per cent cider is about 4.3 UK units, which is more alcohol than most people associate with a single glass of anything.

Sweetness, fruit character and carbonation reduce the perception of strength, so the internal sense of how much has been drunk is systematically unreliable for sweet strong ciders.

Draught and farm cider varies between batches, and mulled or mixed drinks have no determinable strength at all.

The morning after

Alcohol is eliminated at a roughly constant rate that cannot be accelerated, so a person who drank heavily in the evening may still have a blood alcohol concentration above a legal limit the following morning. Sleep does not clear alcohol; it merely removes the subjective sense of being affected.

This is the situation in which drivers are most often caught out, because the feeling of impairment has largely passed while the concentration has not. It is also the situation in which self-assessment is least reliable, because the drinker feels normal.

There is no method of calculating when a specific person will be below a limit. Where any doubt exists, the position is unresolved, and driving on an unresolved position is a decision with consequences for other people as well as for the driver.

What the limit is not

A legal limit is a threshold for an offence, set by legislators balancing enforcement, evidence and public acceptability. It is not a scientific finding that driving below it is unaffected by alcohol.

Measurable impairment of reaction time, judgement and divided attention begins at blood alcohol concentrations below every limit in force in the United Kingdom. A driver who is under the limit may still be impaired, and may still be prosecuted for driving while unfit through drink, which is a separate offence from being over the prescribed limit.

CiderHQ states this because the framing of the question — "how much can I drink and still drive" — presupposes that there is a safe quantity to be identified. There is not one that can be identified for an individual, and the presupposition is the part of the question that is wrong.

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What this page is

A description of what is known, written for readers of legal drinking age. It is not medical advice and it is not an encouragement to drink. CiderHQ publishes no health benefits for alcohol, because current guidance from the major health authorities does not support them. For advice about your own drinking, speak to your national health service. Our policy on alcohol.

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