# On a FX volatility smile, Is a-delta put volatility equal to (1-a)-delta call volatility?

On a FX volatility smile in terms of delta, If I want 95-delta put vol, Is this volatility equal to a 5-delta call vol, and viceversa?

Thanks.

It depends on the delta convention. The parity $$\Delta_{\text{Put}(\text{strike } K)} = 1 - \Delta_{\text{Call}(\text{strike } K)}$$ works only when the delta convention is forward delta, so the 95-delta put vol is equal to the 5-delta call vol only in this case.