diff --git a/docker-compose.yml b/docker-compose.yml
index 696b30c..921e9bc 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -93,6 +93,16 @@ services:
       # If unset -> disabled (OpenWrt auto upgrade is enabled)
       #DISABLE_OPENWRT_AUTO_UPGRADE: "true"
 
+      # Resizes the OpenWrt disk image when the container runs the first time.
+      # Notes:
+      #  * In a additional step you need to resize the partitions inside OpenWrt
+      #    Follow: https://openwrt.org/docs/guide-user/advanced/expand_root
+      #  * If you want to resize the OpenWrt after the container first time run
+      #    Follow: https://github.com/AlbrechtL/openwrt-docker/issues/34#issuecomment-2795886248
+      # Value: Size im MB (minimal 512)
+      # If unset -> no resize (OpenWrt default image size)
+      #IMAGE_SIZE_ON_INIT: "512"
+
       # Enable debugging mode.
       # Showing the final qemu command and OpenWrt bootlog
       # If unset -> disabled
diff --git a/src/helpers.sh b/src/helpers.sh
index 8ed08ee..29b695c 100644
--- a/src/helpers.sh
+++ b/src/helpers.sh
@@ -19,5 +19,6 @@ trap 'error "Status $? while: $BASH_COMMAND (line $LINENO/$BASH_LINENO)"' ERR
 : "${LUCI_WEB_BUTTON_JSON:=""}"   # Adapt the "OpenWrt LuCI web interface" button to your needs.
 : "${OPENWRT_AFTER_BOOT_CMD:=""}" # User command or script to run after OpenWrt is booted
 : "${DISABLE_OPENWRT_AUTO_UPGRADE:=""}"  # Disables the OpenWrt upgrade check every container startup
+: "${IMAGE_SIZE_ON_INIT:=""}"  # New OpenWrt disk image size
 : "${IS_U_OS_APP:=""}"    # By default this container is not a u-OS app
 : "${DEBUG:=""}"          # Disable debugging
diff --git a/src/install_openwrt_rootfs.sh b/src/install_openwrt_rootfs.sh
index 8851311..d522290 100644
--- a/src/install_openwrt_rootfs.sh
+++ b/src/install_openwrt_rootfs.sh
@@ -11,11 +11,24 @@ FILE=/storage/squashfs-combined-${OPENWRT_IMAGE_ID}.img
 if [[ ($DISABLE_OPENWRT_AUTO_UPGRADE != "true") ||  (! -f /storage/current_version) ]]; then
   if [ -f "$FILE" ]; then
       info "$FILE exists. Nothing to do."
-  else 
+  else
       info "$FILE does not exist. Copying squashfs-combined-${OPENWRT_VERSION}.img to storage ..."
       cp /var/vm/squashfs-combined-${OPENWRT_VERSION}.img.gz /storage/squashfs-combined-${OPENWRT_IMAGE_ID}.img.gz
       gzip -d /storage/squashfs-combined-${OPENWRT_IMAGE_ID}.img.gz
-      
+
+      # Check if IMAGE_SIZE_ON_INIT is set
+      if [[ -n "$IMAGE_SIZE_ON_INIT" ]]; then
+          # Check if IMAGE_SIZE_ON_INIT is greater than 511
+          if [[ "$IMAGE_SIZE_ON_INIT" -gt 511 ]]; then
+              info "Resize OpenWrt to $IMAGE_SIZE_ON_INIT MB"
+              dd if=/dev/zero of="/storage/squashfs-combined-${OPENWRT_IMAGE_ID}.img" seek="$IMAGE_SIZE_ON_INIT" obs=1MB count=0
+          else
+              error "Error: IMAGE_SIZE_ON_INIT must be greater than 511."
+              rm /storage/squashfs-combined-${OPENWRT_IMAGE_ID}.img
+              exit 1
+          fi
+      fi
+
       if [ -f "/storage/current_version" ]; then
         mv /storage/current_version /storage/old_version
       fi