When Will I Be Sober?

When Will I Be Sober is an online alcohol units calculator, that tells you when you should avoid driving until, after a big night out/lively lunch/depressing breakfast.

It’s designed to be a) good looking and b) simple enough that severely hungover people can operate it.

Site is currently on version 0.8. Check it out currently at http://whenwillibesober.com, and see where its going with the roadmap below


0.1  – Plan site, work out functionality.
0.2 – Come up with basic design.
0.3 – Build design in HTML & CSS.
0.4 – Throw in AJAX functionality, and PHP.
0.5 – Generate “When” section with correct times, and hunt out bugs.
0.6 – Add a disclaimer and explanation to “Why” section.

0.7 – Add database input, to save all tests done.
0.8 – Add a “Who” section, draw a lovely graph from all the database data.
0.9 – Add social media, and contact drinkaware.co.uk, and other campaigns, get some cross links going.
1.0 – Add “Advanced” section, to allow for more detailed alcohol input.
1.1 – Massive corporate sponsorship: Aiming for a huge header banner, at least 600 pixels high, advertising Jack Daniels. Retire.

33 thoughts on “When Will I Be Sober?

  1. Hi, I am doing an alcohol abuse project for my second year ICT project at college. I was wondering whether it would be possible to include this in project, solely for that purpose and for no commercial or other use. If not possible if there anywhere you can reccomend to show me how to create this calculator if not to complicated or another site which would allow me to use the calculator.

    Many thanks

    1. Hey Josh. I’d be happy to let you have the source code. It’s a fairly simple php based calculation, based on average strengths and volumes of alcoholic drinks. Send me your email address through the contact form, and I’ll send it your way…

    2. Hey Chris
      Thanks a lot, that would be much appreciated. Hopefully should not be too complicated to put in to Flash.


  2. Hi like this website and calculator tool but surely you should calculate from when you stopped drinking rather than when you started?

    1. Hi Julie, thanks for that. The point is that once the liquid is in your body your liver can begin to break down the alcohol. So as soon as you start drinking, your liver can start working. The tool isn’t perfect, but if you drink 10 pints, your liver will definitely begin to work in the hour after you start rather than waiting until you have drunk all ten pints before kicking in.

    1. Its a nice idea, however, quantity and strength of narcotics is much harder to quantify – “I smoked one joint” – that could be a small rollup, mostly tobacco with a sprinkling of low strength resin, or a huge length of pure buds and seed, which would have a vastly different amount of THC, the active ingredient.

    1. At the top, in the What? section? But how many people will know how many units they have drunk? If they know it, its very easy: You will be in sober from n hours after you started drinking, where n is number of units.

  3. You don’t drink all of the alcohol at the instant you start drinking, so the calculation could be improved by adding a time period over which the units were consumed.

    Also the ability to add the strength and quantity of alcohol would much improve this site. I know it’s only meant to be an approximation, but as it stands it’s pretty much useless.

    1. Thanks for the feedback. It definitely aims to be a rough calculation, rather than 100% accurate. Even if you put in exactly the right amount of alcohol, you can’t account for minor differences in rate of liver metabolism. If it calculated everything completely correctly, but your liver worked 10% slower than average, then the calculator would be more likely to advise you that you were safe when you weren’t.

      So I’m happy to use slightly conservative values, to allow for a safety margin. There’s good evidence that people don’t know how much they are drinking, don’t know how much alcohol there is in a drink, and underestimate the time needed to sober up. I wouldn’t say its useless at the moment – just realistic.

    2. Hi Chris,

      Thanks for the response. I was maybe a bit harsh when I said “useless” if this is aimed at pretty-much clueless people who drink e.g. bottles of Bud.

      However, I suspect you are way off the mark when you talk of using “slightly conservative values”: my point is that ABV can vary so wildly, as can bottle sizes. I happen to have a 660ml bottle of 11% beer in my cupboard; I bet your calculator would not be making a conservative estimate if I entered 1 bottle of beer, as your interface suggests I should.

      Now, you could argue that people should realise neither an 11% beer nor a 660ml bottle are standard, but you already implied you are aiming this at the alcohol-uneducated, and how could they be expected to compensate anyway, when you don’t even indicate what “standard” values you are using.

      It’s a noble project, but I would suggest allowing people to adjust volumes and ABV – or at the very least making them visible.

      What values are you using anyway? 5% for beer and 355ml? I wouldn’t even begin to guess with cider as there isn’t really a standard: it commonly varies from about 3% up to 9% and the bottles are using 1 litre, 2 litres, or 3 litres.

    3. Hi Michael,

      Sorry, missed the reply here.

      Yes, its true, there are a number of problems with the calculator. I may consider doing an “advanced” mode in future variations: your comments have been taken on board!


  4. Hi, Chris.
    Thanks for the very useful wee program.

    As you probably know, the Scottish Government are about to change the allowable quantity of alcohol in the bloodstream – from 80 down to 50. Is there any chance of a “Scottish version” of your program to take account of the change?



    1. Hi Jim,

      It’s not something I’ve got on the cards at the moment, but I’d consider it. The thing is, the algorithm at the moment basically allows for around half a unit of alcohol, which errs on the side of caution for the rest of the UK, and is probably about on the nail for the Scottish law.

      The problem is that no calculator can be that precise, because things like body fat, metabolism, contents of stomach, level of dehydration affect these things. If you and I both drank two pints of beer, what our circulating blood volume of alchohol is over the next 3-5 hours would likely be fairly different, and we would be legally able to drive at times up to an hour apart from each other.

      So, what I’d say is that the calculator probably works adequately for both Scotland and England, and if there’s any doubt, you should wait until the completely sober time stated on the calculator.

      Thanks for the email,

  5. Hi
    Michael asks about timescale, but I don’t think you responded?
    Anyway I just entered my quantities from yesterday and it said I would be sober by 11.30, however that’s when I had my last drink. Are you going to put a finish time on this very handy site, as this would definitely make it more useable.


    1. Hi Lynette. I’m intrigued to see what amounts you entered. Your liver starts metabolising pretty much from the moment alcohol enters your blood stream: If you drank just one unit an hour, you basically wouldn’t get drunk. So the calculator needs the start time, not the end time.


  6. Hi Chris. Thanks and congratulations for your drink/drive calculator. I would ignore the criticisms that it’s not 100% accurate. Even if it was, it couldn’t take into account things like short measures, how much people had eaten and individual metabolisms. I guess publishing the average ABV used for the different categories used on the tool would help folk adjust their results if they wanted to and I would imagine that would be fairly simple to do. I say “imagine” because I actually have no idea! 🙂

    A positive, and no doubt intended, effect of the reduction in drink/drive limit in Scotland, where I live, is an increase in people’s awareness of the morning after issues. Your site helps that. Thanks again.

  7. I’m a bit confused I drink fosters the beer is 1.8 units if I drink 7 I’m told I cant drive till 11 am

  8. Hiya Chris,

    I’m with Dave (comment 18) on this one – definitely ignore the less than constructive criticism from pedants – for a ‘rough idea’ (which is all you could possibly expect from the internet anyway without taking into account many variables such as height, weight, even medical history… blah blah blah – and would make the site far too complicated for a hungover person to deal with!), it’s excellent.

    As a new driver trying to be as safe as possible, I’ve come to your page a few times now – and even used it while still drinking to see if it would be safe to drink more units as I had to drive at some point the next day. I decided not to open the other bottle as it most likely wouldn’t have been. I tend to err on the side of caution too and love that you’ve done that with your calculations.

    The fact you’ve clearly stated in bold letters that ‘This tool is only an estimate’… SHOULD have been enough to keep the pedants off your back. Still – it is the internet lol.

    Thanks again for helping to keep the roads an ever so slightly safer place.

  9. Hi Chris, I just wanted to say thank you for this very useful tool. My kids and their mates have recently started driving and so many of their friends just don’t realise that they are ‘drink driving’ the morning after. I have got this calculator out many a time and they are “Whoa but I feel absolutely fine!” so they are now realising that they need to drink less if they have to drive in the morning. I appreciate that it really is impossible to be 100 percent accurate but it gives a very good indication and has certainly made a lot of our friends stop and think as they really didn’t realise how much alcohol is in their system. So once again thank you very much for this guide, it is proving itself invaluable!

  10. Thanks for this. It helped inform my decision to work from home today rather than drive to the office the morning after the works Christmas bash. I have circulated it around workmates. It is a very useful tool.

    1. Ha, awesome, glad to help. Incidentally, our stats over Christmas are always hilarious. Turns out the world drinks a LOT over December

  11. A bit confused. 6 bottles of beer is 11 units and 6 cans of beer is 15. Can and bottle are both 355ml here in Canada.

  12. After a long hard wait i get my antibuse tomorrow and i have worked so hard to get it and this site helped me so much an thank you.

  13. #1.) why does it use military time, but also include am/pm? is there such a thing as 13:00a.m.? no? then why not just say 1am or 1pm?

    #2.) i measured my bottle of liquor and got the total amount “missing”. then used this calculator, i never paid attention to the result much except the fact it said “11”. about 12 (noon) i got in my truck (with a mandatory blowbox device) blew, it worked and i drove.
    later i was explaining to my girlfriend why i had the measuring cups full off booze…. showed her the site, did the same math i used earlier and noticed it said id be good by 11pm. yet i blew fine at 11am.
    same thing is happening right now. i had 10 beers at 4pm today, its 9:44pm now. your calculator is telling me i wont be good until like 10-11pm tomorrow. 24 hours to dissolve 10 beers? the math is off, ill prove it when i blow in my blowbox tommorow at 6:30-7am tomorrow.

    1. correction, it says 10 beers starting 4:00pm today, i willnot be sober until 5pm tomorrow. i think it means to say 5am.

    2. Firstly, thanks for using the site. It’s a rough guide that errs on the side of caution.

      The average bottle of beer contains just under 2 units of alcohol, and the average liver processes around 1 unit per hour.

      So if you start drinking 10 beers at 4pm, it’ll take approximately 20 yours to be completely sober. I put that into the calculator and it shows 11am on the site.

      So, it seems to be right? I guess maybe you put the wrong time AM Vs PM in? I used 24 hour time as that’s what we use in the UK and most of the world, but I put in AM and PM to help out Americans who are less comfortable with 24 hour time.


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