How to determine interplanar spacing for BCC/FCC crystals?

I have a query as to how interplanar spacing in fcc and bcc can be determined. In line with the known formula,

$$d_{hkl} = frac{a}{sqrt{h^2+k^2+l^2}}$$

for a crystal with Miller indices (1 1 0), if the crystal is scc/bcc then the formula holds good!
But for fcc, it does not! According to the formula, the spacing is $frac{a}{sqrt{2}}$, but in practical observation it is $frac{a}{2sqrt{2}}$.

I searched for a distinct formula on the internet to satisfy the fcc case, but I failed! I read some books, looked at some questions, and the author uses the ordinary formula to solve the questions.

I’m confused!
Help me to understand where I’m incorrect!