diff --git a/voussoirkit/imagetools.py b/voussoirkit/imagetools.py
new file mode 100644
index 0000000..9f979c2
--- /dev/null
+++ b/voussoirkit/imagetools.py
@@ -0,0 +1,19 @@
+def fit_into_bounds(image_width, image_height, frame_width, frame_height, only_shrink=False):
+    '''
+    Given the w+h of the image and the w+h of the frame,
+    return new w+h that fits the image into the frame
+    while maintaining the aspect ratio.
+
+    (1920, 1080, 400, 400) -> (400, 225)
+    '''
+    width_ratio = frame_width / image_width
+    height_ratio = frame_height / image_height
+    ratio = min(width_ratio, height_ratio)
+
+    new_width = int(image_width * ratio)
+    new_height = int(image_height * ratio)
+
+    if only_shrink and (new_width > image_width or new_height > image_height):
+        return (image_width, image_height)
+
+    return (new_width, new_height)