The measure of one interior angle in a regular pentagon can be calculated using the formula for the interior angle of a regular polygon:
\[ \text{Interior angle} = \frac{(n - 2) \times 180°}{n} \]
where \( n \) is the number of sides. For a pentagon, \( n = 5 \).
\[ \text{Interior angle} = \frac{(5 - 2) \times 180°}{5} = \frac{3 \times 180°}{5} = \frac{540°}{5} = 108° \]
Therefore, the measure of one interior angle in a regular pentagon is 108°.