It’s one of the most common mistakes people make when drinking alcohol: underestimating how much they’ve had. Many people assume they know what counts as “one standard drink”, but in most cases, they’re wrong. And that misunderstanding can cost you—especially if you’re asked to take part in roadside or workplace alcohol testing.
So, what is a standard drink?
A standard drink is a measure of alcohol, not a measure of liquid. In Australia, a standard drink contains 10 grams of pure alcohol, regardless of the type of beverage. That means a standard drink isn’t defined by the size of the bottle, glass or can. Instead, it’s defined by how much alcohol is inside.
While the concept sounds simple, in practice it can be confusing. Beers come in different strengths. Wine glasses vary in size. Spirits can be poured generously. Cocktails contain multiple ingredients. All these variables make it easy to underestimate how much alcohol you’ve consumed.
How Many Standard Drinks Are in Common Alcoholic Beverages?
Here are some typical examples:
- Full-strength beer (4.8% alcohol): A 285ml glass (a middy/pot) is about 1.1 standard drinks. A 375ml can contains about 1.4 standard drinks.
- Mid-strength beer (3.5% alcohol): A 375ml can equals around 1 standard drink.
- Wine (13% alcohol): A 150ml pour contains 1.5 standard drinks. Many restaurant pours are larger, meaning more alcohol than you expect.
- Spirits (40% alcohol): A standard nip of 30ml is 1 standard drink. However, at home or at parties, people often pour much more.
- Cocktails: These vary widely and often contain multiple shots of alcohol. A single cocktail can easily contain two, three, or even four standard drinks.
Because serving sizes and alcohol strengths vary, you can drink more alcohol than you realise. This misunderstanding is one reason why people fail roadside and workplace alcohol testing, despite thinking they haven’t had much to drink.
Why Understanding Standard Drinks Is So Important
Knowing what a standard drink is matters for several reasons, especially around driving, workplace safety, and managing risk.
- Roadside Alcohol Testing
Police conduct alcohol testing to protect all road users. If you underestimate your alcohol intake, you could easily blow over the limit. Your breath alcohol concentration depends on many factors—body size, gender, food intake, timing, and alcohol strength. Misjudging a couple of drinks or even a single drink can put you over the legal limit.
- Workplace Alcohol Testing
Like on the roadside, many workplaces carry out alcohol testing to protect employees and meet WHS obligations. If you’re operating machinery, driving, or working in a high-risk environment, having alcohol in your system can cause accidents, injuries, or worse. Understanding standard drinks helps you better judge whether you’re fit for work and reduces the risk of breaching your employer’s workplace alcohol testing policy.
- Safety for Yourself and Others
While safety on the roads and in workplaces is important, it can be important in other parts of our lives. Even small amounts of alcohol can affect coordination, judgement, and reaction time. A point worth knowing if you’re, for example, working around the home, or walking around traffic. By understanding what you’re consuming, you can make safer decisions about when to stop drinking or when to delay doing activities that require you to be alert.
Using Tools to Better Estimate Your BAC
Once you understand standard drinks, you’re in a stronger position to judge whether you’re safe to drive or go to work.
To help, you can use online tools such as calculators. They help you estimate your breath alcohol content based on what you’ve consumed, your weight and the number of hours you’ve been drinking. Keep in mind, though, that these calculators are only a guide.
For greater reassurance, consider using a quality personal breathalyser, such as the Dräger Alcotest 4000. It gives a reading that doesn’t rely on your ability to calculate standard drinks.
However, remember that personal breathalysers should only be used as a guide. Accuracy can vary depending on calibration, environment, and timing. And, above all, the quality of your unit.
The Only Way to Be Absolutely Sure
While understanding standard drinks, using a calculator, or owning a quality breathalyser can help you make safer choices, there is only one way to be completely certain you’re safe to drive or go to work. There’s only one way to ensure you will not fail roadside or workplace alcohol testing.
Don’t drink at all.
If you have any doubt, choose caution. Alcohol affects everyone differently, and no estimate is perfect.
Understanding standard drinks empowers you to make safer decisions, protect yourself, and avoid serious consequences. It’s a simple step that can prevent life-changing mistakes.
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Learn what a standard drink is and why it matters for driving and workplace alcohol testing. Understand drink sizes, alcohol content and safer choices. Integrity Sampling explains what you need to know.
