diff --git a/docs/generating_the_url_advanced.md b/docs/generating_the_url_advanced.md
index dd245b39..a1a5ae50 100644
--- a/docs/generating_the_url_advanced.md
+++ b/docs/generating_the_url_advanced.md
@@ -59,7 +59,8 @@ rt:%resizing_type
 Defines how imgproxy will resize the source image. Supported resizing types are:
 
 * `fit`: resizes the image while keeping aspect ratio to fit given size;
-* `fill`: resizes the image while keeping aspect ratio to fill given size and cropping projecting parts.
+* `fill`: resizes the image while keeping aspect ratio to fill given size and cropping projecting parts;
+* `auto`: if both source and resulting dimensions have the same orientation (portrait or landscape), imgproxy will use `fill`. Otherwise, it will use `fit`.
 
 Default: `fit`
 
diff --git a/docs/generating_the_url_basic.md b/docs/generating_the_url_basic.md
index baef7218..18347ad4 100644
--- a/docs/generating_the_url_basic.md
+++ b/docs/generating_the_url_basic.md
@@ -24,7 +24,8 @@ Once you set up your [URL signature](./configuration.md#url-signature), check ou
 imgproxy supports the following resizing types:
 
 * `fit`: resizes the image while keeping aspect ratio to fit given size;
-* `fill`: resizes the image while keeping aspect ratio to fill given size and cropping projecting parts.
+* `fill`: resizes the image while keeping aspect ratio to fill given size and cropping projecting parts;
+* `auto`: if both source and resulting dimensions have the same orientation (portrait or landscape), imgproxy will use `fill`. Otherwise, it will use `fit`.
 
 #### Width and height
 
diff --git a/process.go b/process.go
index 870eee11..50c8ee8b 100644
--- a/process.go
+++ b/process.go
@@ -49,11 +49,24 @@ func calcScale(width, height int, po *processingOptions, imgtype imageType) floa
 		wr := float64(po.Width) / srcW
 		hr := float64(po.Height) / srcH
 
+		rt := po.Resize
+
+		if rt == resizeAuto {
+			srcD := width - height
+			dstD := po.Width - po.Height
+
+			if (srcD >= 0 && dstD >= 0) || (srcD < 0 && dstD < 0) {
+				rt = resizeFill
+			} else {
+				rt = resizeFit
+			}
+		}
+
 		if po.Width == 0 {
 			scale = hr
 		} else if po.Height == 0 {
 			scale = wr
-		} else if po.Resize == resizeFit {
+		} else if rt == resizeFit {
 			scale = math.Min(wr, hr)
 		} else {
 			scale = math.Max(wr, hr)
diff --git a/processing_options.go b/processing_options.go
index 1ea8366d..16696e64 100644
--- a/processing_options.go
+++ b/processing_options.go
@@ -58,12 +58,14 @@ const (
 	resizeFit resizeType = iota
 	resizeFill
 	resizeCrop
+	resizeAuto
 )
 
 var resizeTypes = map[string]resizeType{
 	"fit":  resizeFit,
 	"fill": resizeFill,
 	"crop": resizeCrop,
+	"auto": resizeAuto,
 }
 
 type rgbColor struct{ R, G, B uint8 }