I think deducting 5% from the Betfair price is not always 100% accurate.

For example, if we had $5 on a $2.00 winner and 5% was deducted from the price it would reduce the price to $1.90. A $5 stake would therefore return $9.50, for a profit of $4.50.

What Betfair does is deduct 5% from the race's profit, not the price. The gross profit in this case would be $5, and deducting 5% from the $5 ($0.25) would produce a profit of $4.75 as opposed to $4.50.

I learnt of this "anomaly" when backing multiple horses but could not manually calculate the profit - it was always more then I expected.

I stand corrected Michael, may I add that I actually pay a lot less then the 5%, but my point still stands.
If you compare the prices there is nowhere an 18% difference, maybe in certain price ranges where the horse has an absolutely minimal chance, then yes.

lomaca, yes, you're right. The larger-priced horses often even double their TAB prices.

I've also looked at Place prices. There does not seem to be much difference, except for those at $1.04 with the TAB. I think my best Betfair price I obtained for a TAB $1.04 was about $1.30.

Thanks Bhags. I might try 3 ticks as suggested. Thanks to you all for your advice.

Where one finds the big difference between TABs & Betfair is when one is doing mutii-bets such as Dutching.

Example
Dutch 4 horses to a Book percentage of say 70%
Commission paid on profit.

Try doing the same with say a TAB
You wont get anywhere near this percentage on the same runners.
The commission is built into the price whether you win or lose on all runners , not just the ones that win , you pay through the reduced price in the form of their Over round on Book percentage which is usually 118.5% which includes their other trick of rounding down of divs, which no one likes talking about.

Example of Rounding down
e.g. If calculated divis actually 1.99 they round down to 1.90 they just keep the difference - funny that.

What about the 1.00 divs one often sees - that's funny too.
No one wants to talk about that either.

I would not want to do business with any one who blatantly snips punters in this manner, but they see nothing wrong with it - funny that.

I now know what the TAB means by chancing your luck.
Lucky to just get your money back after risking a ...
100% Liability .
Possible Zero div if successful, but you wont know until after the race, because what you see before the race, is not necessarily what you get.
100% loss if unsuccessful.

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CONVERTING BF PRICE

If one wishes to convert the Betfair price to a net price with com taken into account.
Then take 5% com off its Fractional odds, (not decimal odds.)
mutiply fractional odds say 4/1 x .95 = 3.8/1

Then convert to Decimal odds = 4.80


Example
5.00 horse.
4/1 x .95 = 3.80 + 1.00 = 4.80 Net BF price

Now this can be compared to TAB price.

This is spot on Bhagwan.
To reduce the commission paid, the more runners in the field you have your total stake spread across, the less relative commission you pay.
Those concentrating on one runner per race are really struggling with commission.
The worst case of course is short priced horses because they have a high strike rate, single bettors who like the longshots don't suffer quite as much.

There are cases where the profit gained outweighs the commission paid relatively because the profit is much more by ratio, but the general rule is, the more horses you back or lay per event, the less commission on total profit you end up paying as a percentage.

Thanks to some good advice here I may have found a fix to the initial problem. I set the bot to 4 ticks and 60 seconds before jump and had them all matched (except 2 that had odds <$1.40) for $75 bets. Problem solved by the wise guys again! Thanks

Yar .Wise guys .

No chump change round here, seeee ,yar.

LOL... Bhagsie Malone?