A standard lot is 100,000 units of the base currency, which may or may not be USD.
[B]A mini-lot is 10,000 units of base currency,[/B] which may or may not be USD. If the [U]base currency[/U] is, in fact, USD (as, for example, in the USD/JPY pair), then a mini-lot is, in fact, $10,000.
However, 1 pip in this case is [B]not[/B] $1.
For an account denominated in USD, one pip = $1 per mini-lot when the [U]quote currency[/U] is USD (as, for example, in the EUR/USD pair).
As mentioned above, one standard lot is 100,000 units of base currency.
Let’s assume that you are trading a pair of the form XXX/USD, in an account denominated in USD, such that 1 pip = $10 per standard lot.
If you trade 0.05 lots, you would be trading 5,000 units of base currency (0.05 x 100,000 = 5,000).
Given that 1 pip is worth [U]$10 per standard lot[/U], we can calculate that —
1 pip is worth [U]$0.50 per 0.05 standard lots[/U] (0.05 x $10 = $0.50).
Notice that your broker’s maximum allowable leverage (50:1 in your example) has no bearing on pip-values. Maximum allowable leverage simply determines how much margin is required on your trades.
Also, the balance in your account ($500 in your example) has no bearing on pip-values.
Pip-values are determined by (1) the [U]quote currency[/U] of the pair you are trading, (2) the currency in which your account is denominated (your account currency), and (3) your position size.
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