diff --git a/components/engine/api.go b/components/engine/api.go
index e870ca7723..4f08b2aae6 100644
--- a/components/engine/api.go
+++ b/components/engine/api.go
@@ -248,6 +248,10 @@ func getContainersJSON(srv *Server, version float64, w http.ResponseWriter, r *h
 	if err != nil {
 		return err
 	}
+	size, err := getBoolParam(r.Form.Get("size"))
+	if err != nil {
+		return err
+	}
 	since := r.Form.Get("since")
 	before := r.Form.Get("before")
 	n, err := strconv.Atoi(r.Form.Get("limit"))
@@ -255,7 +259,7 @@ func getContainersJSON(srv *Server, version float64, w http.ResponseWriter, r *h
 		n = -1
 	}
 
-	outs := srv.Containers(all, n, since, before)
+	outs := srv.Containers(all, size, n, since, before)
 	b, err := json.Marshal(outs)
 	if err != nil {
 		return err
diff --git a/components/engine/commands.go b/components/engine/commands.go
index 05a484ddb1..2f84f357d1 100644
--- a/components/engine/commands.go
+++ b/components/engine/commands.go
@@ -867,6 +867,7 @@ func (cli *DockerCli) CmdImages(args ...string) error {
 func (cli *DockerCli) CmdPs(args ...string) error {
 	cmd := Subcmd("ps", "[OPTIONS]", "List containers")
 	quiet := cmd.Bool("q", false, "Only display numeric IDs")
+	size := cmd.Bool("s", false, "Display sizes")
 	all := cmd.Bool("a", false, "Show all containers. Only running containers are shown by default.")
 	noTrunc := cmd.Bool("notrunc", false, "Don't truncate output")
 	nLatest := cmd.Bool("l", false, "Show only the latest created container, include non-running ones.")
@@ -893,6 +894,9 @@ func (cli *DockerCli) CmdPs(args ...string) error {
 	if *before != "" {
 		v.Set("before", *before)
 	}
+	if *size {
+		v.Set("size", "1")
+	}
 
 	body, _, err := cli.call("GET", "/containers/json?"+v.Encode(), nil)
 	if err != nil {
@@ -906,7 +910,12 @@ func (cli *DockerCli) CmdPs(args ...string) error {
 	}
 	w := tabwriter.NewWriter(os.Stdout, 20, 1, 3, ' ', 0)
 	if !*quiet {
-		fmt.Fprintln(w, "ID\tIMAGE\tCOMMAND\tCREATED\tSTATUS\tPORTS\tSIZE")
+		fmt.Fprint(w, "ID\tIMAGE\tCOMMAND\tCREATED\tSTATUS\tPORTS")
+		if *size {
+			fmt.Fprintln(w, "\tSIZE")
+		} else {
+			fmt.Fprint(w, "\n")
+		}
 	}
 
 	for _, out := range outs {
@@ -916,10 +925,14 @@ func (cli *DockerCli) CmdPs(args ...string) error {
 			} else {
 				fmt.Fprintf(w, "%s\t%s\t%s\t%s ago\t%s\t%s\t", utils.TruncateID(out.ID), out.Image, utils.Trunc(out.Command, 20), utils.HumanDuration(time.Now().Sub(time.Unix(out.Created, 0))), out.Status, out.Ports)
 			}
-			if out.SizeRootFs > 0 {
-				fmt.Fprintf(w, "%s (virtual %s)\n", utils.HumanSize(out.SizeRw), utils.HumanSize(out.SizeRootFs))
+			if *size {
+				if out.SizeRootFs > 0 {
+					fmt.Fprintf(w, "%s (virtual %s)\n", utils.HumanSize(out.SizeRw), utils.HumanSize(out.SizeRootFs))
+				} else {
+					fmt.Fprintf(w, "%s\n", utils.HumanSize(out.SizeRw))
+				}
 			} else {
-				fmt.Fprintf(w, "%s\n", utils.HumanSize(out.SizeRw))
+				fmt.Fprint(w, "\n")
 			}
 		} else {
 			if *noTrunc {
diff --git a/components/engine/server.go b/components/engine/server.go
index e9be3a1668..f70ea755fe 100644
--- a/components/engine/server.go
+++ b/components/engine/server.go
@@ -251,7 +251,7 @@ func (srv *Server) ContainerChanges(name string) ([]Change, error) {
 	return nil, fmt.Errorf("No such container: %s", name)
 }
 
-func (srv *Server) Containers(all bool, n int, since, before string) []APIContainers {
+func (srv *Server) Containers(all, size bool, n int, since, before string) []APIContainers {
 	var foundBefore bool
 	var displayed int
 	retContainers := []APIContainers{}
@@ -285,8 +285,9 @@ func (srv *Server) Containers(all bool, n int, since, before string) []APIContai
 		c.Created = container.Created.Unix()
 		c.Status = container.State.String()
 		c.Ports = container.NetworkSettings.PortMappingHuman()
-		c.SizeRw, c.SizeRootFs = container.GetSize()
-
+		if size {
+			c.SizeRw, c.SizeRootFs = container.GetSize()
+		}
 		retContainers = append(retContainers, c)
 	}
 	return retContainers