Leverage

If you know your actual account balance (which is hopefully bloody obvious) and your average stop loss used on your trades (providing your trading system has a close range in typical stops placed) and finally the average or fixed risk as a percentage of the account balance placed on each trade (know as ‘r’ for the geeky folks) then you can estimate the actual leverage employed on your trades before even opening an fx account and worrying about what maximum leverage to accept.

For example.
Account balance $20,000
Risk per trade 2%
Average typical stop 50 pips
2% of $20,000 = $400
$400 / 50 pips = $8 per pip

Let’s assume you trade currency pair ending in xxx/usd where one standard lot is $10 per pip (a notional value of $100,000) So, $8 per pip has a notional value of $80,000 against an account balance of $20,000.

Leverage used on this trade is
80,000 / 20,000 = 4.0
Leverage employed 1:4

So why take an account with 1:100 leverage when you need only 4% of this.

(You should take into account required margin too which is subtracted from your balance as the trade is placed)