Maximum Lot Size
I have not found any websites or apps that will calculate the maximum lot size using account size and margin. I have put together some examples in the spreadsheet below.
Alternatively, this link will allow you to enter margin rate and lot size to determine the account size needed for that number of lots. Keep entering lot sizes until it calculates your account amount. This does not consider the trade being in a negative position which would increase the margin requirements. With Oanda, if you are in a margin call situation, you have three days to remedy the situation. Some other brokers will immediately close your positions. Go to the link below and click on the “Margin” tab.
https://www.xm.com/forex-calculators/margin#forex-calculator
In this example, the account currency is USD and we want to find out the margin/lots for a EURUSD trade. From the drop-down select a leverage of 50 (this is the maximum leverage for EURUSD for an Oanda acocunt). Our account size is $15,000 so we know that from the Account Type drop-down we need to select Micro lots. Enter in different volume in Lots and then click to Calculate button to determine the Required Margin (account size) needed. In this case, we can trade at least 500 micro lots. If you are trading mini lots, this would be 500 / 10 or 50 mini lots.
1 standard lot = 10 mini lots = 100 micro lots.
Oanda’s margin rates can be found here – https://www.oanda.com/resources/legal/united-states/legal/margin-rates. On the right-hand size, select the maximum margin that your account has. This is a setting that you specify for your account. The maximum is 50:1. You will then see, for example, that the EURUSD margin requirement is 2%. 1/.02 = 50. So when the maximum margin is 50:1, the EURUSD is also 50:1. There are other currency pairs with higher margin requirements.
Pip Value Calculator
To calculate the Profit/Loss for a one pip movement, use the same link as above and click on the “Pip Value” tab. Select the currency pair, the account currency, the account type and enter the volume. Click the “Calculate” button. I this case, each pip is worth $50.
Profit and Loss Calculator
If you click on the Profit & Loss tab, you can enter the data to calculate P&L in $ or pips. In the top of the screen, you would enter the “Set Stop Loss Amount” and the “Set Take Profit Amount” in $’s (for a USD account) and when you click the “Calculate” button, the price of the stop loss and take profit will be calcualted. For the bottom of the screen you would enter the Set Stop Loss and Set Take Profit in pips and stop loss and take profit will be calculated in $’s (for a USD account).