One of the most powerful tools in betting is dutching. It's a way of backing two or more horses at fixed odds for an equal profit should any of selection win.

With the advent of mobile phone technology access to these calculators is now available on the course as well as when you are betting from home. I have put up a very simple fixed stake dutching calculator that can be accessed from most modern mobile phones and web browers

The main version can be seen at: http://www.bismarckbookie.co.uk/dutchingCalculator.html
The mini version for use on mobile phones can be found at: http://www.bismarckbookie.com/miniDutchingCalculator.html

I have done my best to ensure that the calculator is quick and easy to use so that you can make use of it alongside the Betfair website.

For those of you interested in how to calculate your own dutch stakes on course you can do it using a simple calculator (like those on most phones):

1. First we need to calculate the total probability of the horses we want to back
   1. Calculate the decimal odds for the first selection (top divided by bottom + 1) e.g. 6/4 + 1 = 2.5
      
   2. The percentage of the book this selection takes up is 1 divided by the decimal odds e.g 1/2.5 = 0.4 means the selection accounts for 40% of the book.
      
   3. Store this value in your calculators memory (M+)
   4. Do the same calculation for each selection and add the result to your calculator's memory; 1 divieded by the decimal odds then press M+
2. To calculate the amount to stake on each horse do the following:
   1. Calculate the selections book percentage (1 divided by it's decimal odds) and divide it by the total percentage of your selections. (Recall this from your calculator memory using MR button) then multiply this by the amount you want to stake e.g. 1 / 2.5 = 0.4 / 0.6 = 0.67 * 10 = 6.67
      
   2. Repeat the above for each selection you want to back

Once you get used to your calculator you should be able to do this quite quickly. Alternatively just use the calculators mentioned above. If the mini calculator doesn't work on your mobile, let me know the make and model and I will see if I can put something together you can use. I have tested the above calculators with the IPhone and a Nokia N95.