I used to stay late at work, but then I realised something crazy.

Getting in a little early and leaving a little late every day might be seen as a good thing by many, but you're massively selling yourself short. Here's why.

A day lost, every week

As of 2015 the typical full-time job in the western world involves working 7.5 hours a day, 5 days a week, 48 weeks a year. You'll have about 30 minutes to eat lunch (usually at work, but not counted in the working hours), and you'll spend 30 minutes commuting each way. You'll believe that you work a 37.5 hour week, but in actuality you'll be spending 9 hours a day, 45 hours a week, on work related stuff. You've already lost 7.5 hours of your time each week, the equivalent of one whole workday, and you probably didn't realise it.

Leaking weeks away

So, lets assume that you work between 9am and 5pm. You might get to the office a little early every day, maybe 8:45am. Then, when 5pm rolls around, maybe you like to hang back a bit to tie off a couple of loose ends, usually getting away at about 5:15pm. No big deal, right? Wrong.

By adding an extra 15 minutes to the start and end of your day, you've increased the time you spend at work by 2.5 hours a week, an extra third of a working day! This means that for every three weeks you work, you'll have worked one extra day for free. Fast forward one year, and you've sacrificed over three weeks of your time!

Time science

Curious how this works? Here's the breakdown:

• 0.5 hours x 5 days = 2.5 hours extra time worked each week
• 2.5 hours x 48 weeks = 120 hours extra time worked each year
• 120 hours / 7.5 = 16 work days extra per year
• 16 days / 5 = 3 working weeks and 1 work day extra per year

Those extra 30 minutes a day really rack up, huh. Would you willingly work an extra three weeks for free to tie up loose ends, or to look committed? If you could have three weeks of your life back right now, for every year that you've done this, would you take them? I know I would.

Do what you love

The truth is, once we've spent our time it's gone, and it can never be claimed back. We all have stuff that we love doing, and unless you really love your job, it's probably not work. So, arrive on time, leave on time, and the next time your boss gives you a funny look because you're downing tools at exactly 5:00pm, remember; you're on your time now.