Hilary Duff was 15 when she filmed A Cinderella Story ; the movie came out in 2004, by which time she had turned 16.

html

<table>
  <tr><th>Detail</th><th>Age</th></tr>
  <tr><td>While filming</td><td>15</td></tr>
  <tr><td>At release</td><td>16</td></tr>
</table>