make images the same size in bootstrap grid

Question

I am creating an image gallery with 3 rows, each containing 3 images by using the Bootstrap grid system. All of the images have different size. What I am trying to do is make all of the images the same size. I tried to use the max-height or max-width in my CSS, however it didn't help to make all the images (thumbnails) similar size. Should I just get rid of the thumbnail class or is there any other solution?

body {
      padding-top: 70px;}
    .row .flex {
     display: inline-flex;
     width: 100%;}
    img {
     width:100%;
     min-height:100px;}

<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<div class="row match-to-row">
      <div class="col-lg-4 col-sm-6">
        <div class="thumbnail">
           <img src="https://source.unsplash.com/eKTUtA74uN0" alt="">
        </div>
      </div>
      <div class="col-lg-4 col-sm-6">
        <div class="thumbnail">
           <img src="https://source.unsplash.com/x-tbVqkfQCU" alt="">
        </div>
      </div>
      <div class="col-lg-4 col-sm-6">
        <div class="thumbnail">
           <img src="https://source.unsplash.com/cjpGSEkXfwM" alt="">
        </div>
      </div>

      <div class="row match-to-row">
        <div class="col-lg-4 col-sm-6">
          <div class="thumbnail">

            <img src="https://source.unsplash.com/63JKK67yGUE" alt="">
          </div>
        </div>
        <div class="col-lg-4 col-sm-6">
          <div class="thumbnail">

            <img src="https://source.unsplash.com/YP6lDrlxWYQ" alt="">
          </div>
        </div>
        <div class="col-lg-4 col-sm-6">
          <div class="thumbnail">

            <img src="https://source.unsplash.com/NqE8Ral8eCE" alt="">
          </div>
        </div>

        <div class="row flex match-to-row">
          <div class="col-lg-4 col-sm-6">
            <div class="thumbnail">

              <img src="https://source.unsplash.com/6oUsyeYXgTg" alt="">
            </div>
          </div>
          <div class="col-lg-4 col-sm-6">
            <div class="thumbnail">

              <img src="https://source.unsplash.com/WF2lvywxdMM" alt="">
            </div>
          </div>
          <div class="col-lg-4 col-sm-6">
            <div class="thumbnail">

              <img src="https://source.unsplash.com/2FdIvx7sy3U" alt="">
            </div>
          </div>
    </div>
  </div>

Answer 1

I think the property you're looking for is object-fit

img {
    width: 200px; /* You can set the dimensions to whatever you want */
    height: 200px;
    object-fit: cover;
}

The object-fit property works similarly to how you would using background-size: cover on a background image to make it fill the page without stretching. This way, you can define a width in a rule that all images will follow to ensure that they are the same size without distorting your picture.

Other values you can use with this property includes:

• fill - stretch the image.
• contain - preserve the aspect ratio of the image.
• cover - Fill the height and width of the box.
• none - Keep the original size.
• scale-down - compare the differences between none and contain to find the smallest object size.

object-fit | CSS-Tricks

Answer 2

Add the css class img-responsive to every image.