Three numbers determine what a price move is worth to you.
Contract size. A standard oil lot conventionally represents 1,000 barrels, matching the underlying futures contract, and many brokers offer fractional lots. Confirm this on the contract specification page for your instrument rather than assuming, because it varies between providers.
Tick value. At 1,000 barrels per lot, a $1.00 move equals $1,000 per lot. Oil is normally quoted to two decimal places, making the minimum $0.01 increment worth $10 per lot.
Margin and leverage. The margin requirement determines how much capital is tied up. Note that leverage on energy instruments is frequently tiered rather than flat: GTCFX publishes a dynamic leverage schedule under which the maximum available leverage on crude oil applies to the first tier and reduces as position size increases.[1] Assuming the headline maximum applies to your whole position is a common and expensive error.
A worked example. You open one lot of WTI at $85.00 and close at $86.20. The move is $1.20, and at $1,000 per dollar per lot that is $1,200 gross. From that, subtract the spread paid at entry and any overnight financing if the position was held past settlement.
Overnight financing. Leveraged oil positions held past the daily settlement window incur a financing charge. On an intraday trade this is irrelevant; on a three-week hold it becomes a significant share of total cost, and it accrues whether the trade is winning or losing. Some providers also apply a multi-day financing charge on one weekday to account for the weekend — check which day applies to your instrument before building a strategy that holds through it.