Forex options are calculated with 'Greeks'. A basic explanation of these 'Greeks' will help you understand how and why the forex options move and behave in a certain way. An option is a derivative and how it's value is derived is from a formula that combines these Greeks together. The Greeks are how these options respond to various factors such as price movement, time decay, volatility, and interest rates.

There are 5 Greeks involved and we share go through them one by one.

Delta:

The speed of the option's price gain or loss against the gain or loss of the 'mother' or underlying asset price is known as the Delta. The Delta is a figure that shows us how fast or slow the option will move relative to its 'mother' or underlying asset. A Delta of 1 means the option price is moving at the same speed and direction as the 'mother' or underlying asset. A Delta of -1 means the option price is moving in the opposite direction for every point the 'mother' or underlying asset moves.

The probability of an option expiring in-the-money is also expressed in the Delta. An at the money call option has a Delta of 0.5; i.e., 50%, meaning a 50% chance of expiring in the money. A deep in the money call will have a Delta of near 1, or 100%, meaning a near 100% chance of expiration in the money. A very out-of-the-money call option will have a Delta of close to zero, meaning a near zero chance of expiring in the money.

Gamma:

Gamma is derived from Delta is the odds of a change in Delta. It also informs in advance if the Delta could be changing. Gammas are positive for both the call and put. When options are deep in the money of deep out of the money the Gammas will be near zero as the probability of a change in Delta are very low. Likewise at strike price the Gamma would likely to e the highest.

Theta:

Time decay is reflected in the option position as Theta. Options bought have negative Theta, which means that each day you do not sell that option, the time value is declining because of the time decay. In this case, time decay is making it worse for the buyer of the option. When you sell options, Theta is positive, meaning that time decay is good for the option seller.

Vega:

How volatility affects the option pricing is reflected in the in Vega. In other words, its sensitivity to volatility. Options tend to have price increases when the underlying asset's volatility increases. In this case, volatility is good for the buyer of an option and bad for the seller of an option. Vega is positive for long option and negative for short option.

Rho:

Rho is how interest rates affect the pricing of the the option. When interest rates are high and it is good for the position, Rho will be positive. If interest rates are high but bad for the option position, Rho will be negative.