'Calculate your daily rate. Say it out loud. 'I'm a £500 a day sort of guy''

Have you ever wondered what a day of your working life is worth?

Now, putting a monetary value on a finite and precious resource, such as a day of your life, is philosophically fragile. Your time, like mine, is priceless. What's more, as the days turn into months and the months into years, scarcity makes it steadily more valuable. But never mind the metaphysics. What is the cost, in hard cash, to the NHS of a day of a manager's time?

A note of encouragement to readers without a formal financial background: the next few paragraphs contain arithmetic. Sums. But be not afraid. They are easy sums and you will feel empowered once you master them. For they define two fundamental aspects of your relationship with your employer - your pay and the amount of time you spend at work to get it - and they point to a third: your productivity.

First, the pay. Let's say, for argument's sake, your current salary is£40,000 per year: the salary level at which HSJ's executive focus job advertisements begin.

But your salary is not the only cost of employing you. Your employer will also have to shell out national insurance contributions and, if you work for the NHS, contribute to the pension scheme. Together, these amount to around 25 per cent of your salary: another£10,000. If you find this amount surprisingly high, you may not have grasped yet why the cost of public sector pensions has become a major political concern in recent years.

And that is not all. You will also expect your employer to pay for some training to keep your skills up to date or prepare you for the next reorganisation. Let's say they spend£1,000 a year, if the strategic health authority doesn't get its sticky hands on the money first.

So an employee with a£40,000 salary actually costs around£51,000 a year. Some would say the true cost is a lot more. We have not included an office for you to sit in, or a computer, or a telephone, or a payroll department to pay your salary, or a human resources department to monitor your development, or a boss to manage your performance.

Second, the amount of time you spend at work. There are 365 days in a year and not even chief executives work on all of them. The conventional calculation of the number of potentially productive working days per year goes:

  • Total weekdays (365 x 5/7).. 261
  • less public holidays.......... ....(8)
  • less annual leave, say........... (30)
  • less training, say.................. (5)
  • less sickness, say.................. (8)
  • Potentially productive days... 210

Now you may quibble with some of these assumptions. Public holidays vary slightly from one year to another and across the UK.

Not everyone gets as much as 30 days leave and some get more. Actual access to training varies. Many would consider eight days sickness absence over-generous, although the NHS average - which includes long-term illness - is considerably higher than the 3 per cent this represents. And the absence of any provision for maternity leave suggests either an all-male workforce or the imminent demise of the human race.

But never mind the quibbles. The final stage is simply to divide one number into the other. Fifty-one thousand pounds for 210 days of productive work represents a cost to the NHS of£242.86 per day for someone on a£40,000 salary. Call it£250 per day for ease of calculation and to allow for missing costs. If you are lucky enough to be on a salary of£80,000 following the recent restructuring, a day of your time is worth roughly twice this: around 500 quid.

At this stage, calculate your own daily rate. Say it out loud. 'I'm a£500 a day sort of guy', or whatever the number and gender might be.

'So what?' you may ask. 'I'm worth it.' And you may well be. But I would suggest this piece of knowledge has a couple of potentially useful applications. The first is that next time you are taking on temporary workers - be they agency clerks, interim managers or management consultants - you have a decent benchmark against which to measure the reasonableness of their pay demands.

But be warned: because few temps manage to work 210 days a year, they tend to expect more money per day. That is the price of their flexibility, for being available when they are needed.

Second and far more important, you can now put a price on all of your time that gets wasted because of the way we work. Instead of grumbling like everyone else about how busy your diary is, or the proliferation of pointless meetings, or the burden of corporate e-mail, you can now easily work out the true cost of the waste. You can annoy your colleagues with smart-arse comments like: 'Do you know, having us all here for the last hour of that meeting cost£1,100 and we couldn't even agree a date for the next meeting?'

Far from being an idle intellectual exercise, this is an important step towards self-empowerment. Ultimately, managers need to manage their own productivity: no-one can do it for them. If you allow a quarter of your 210 potentially productive days to be frittered away on meaningless administrative tasks, you will achieve less than a colleague who only wastes 10 per cent, however hard you try to catch up at the weekend. Knowing the cost of waste acts as a spur. It is the managerial equivalent of marking the prices of clinical supplies on the boxes so nurses know the cost of what they are opening.

The NHS Institute's excellent Releasing Time to Care programme (Productive Ward) uses lean principles and incorporates a decade of service improvement learning, but its core is empowerment at ward level. If you are attending its introductory events, you might ponder: what would a 'releasing time to manage' programme look like? It would surely have a lot to do with time management.

Noel Plumridge is an independent consultant and former NHS finance director.