To find the unit rate for 1 bag of chips given that 5 bags cost $6.25, we can divide the total cost by the number of bags.
\[ \text{Cost for 1 bag} = \frac{\text{Total Cost}}{\text{Number of Bags}} = \frac{6.25}{5} = 1.25 \]
Thus, the unit rate for 1 bag of chips is $1.25.
Therefore, the correct response is $1.25.