diff --git a/README.md b/README.md
index 6f4df08d..25fe8194 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ dependencies {
 }
 ```
 
-**2)** Add the ``com.melnykov.fab.FloatingActionButton`` to your layout XML file. The button should be placed in the bottom right corner of the screen. The width and height of the floating action button are hardcoded to **56dp** for the normal and **40dp** for the mini button as specified in the [guidelines].
+**2)** Add the ``com.melnykov.fab.FloatingActionButton`` to your layout XML file. The button should be placed in the bottom right corner of the screen. The width and height of the floating action button are hardcoded to **56dp** for the normal and **40dp** for the mini button as specified in the [guidelines], but can also be overridden manually via the ``fab_size`` dimension attribute, if this special case is required.
 
 ```xml
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
diff --git a/library/src/main/java/com/melnykov/fab/FloatingActionButton.java b/library/src/main/java/com/melnykov/fab/FloatingActionButton.java
index 3f88ddf8..34b45956 100644
--- a/library/src/main/java/com/melnykov/fab/FloatingActionButton.java
+++ b/library/src/main/java/com/melnykov/fab/FloatingActionButton.java
@@ -37,6 +37,7 @@
 
 public class FloatingActionButton extends ImageButton {
     private static final int TRANSLATE_DURATION_MILLIS = 200;
+    private static final float SHADOW_SIZE_RELATIVE = 0.2f; // shadow padding relative to width / height, based on fab_shadow & fab_shadow_mini drawables.
 
     @Retention(RetentionPolicy.SOURCE)
     @IntDef({TYPE_NORMAL, TYPE_MINI})
@@ -54,6 +55,7 @@ public class FloatingActionButton extends ImageButton {
     private int mColorDisabled;
     private boolean mShadow;
     private int mType;
+    private int mSize;
 
     private int mShadowSize;
 
@@ -80,8 +82,7 @@ public FloatingActionButton(Context context, AttributeSet attrs, int defStyle) {
     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
-        int size = getDimension(
-            mType == TYPE_NORMAL ? R.dimen.fab_size_normal : R.dimen.fab_size_mini);
+        int size = mSize;
         if (mShadow && !hasLollipopApi()) {
             size += mShadowSize * 2;
             setMarginsWithoutShadow();
@@ -97,11 +98,15 @@ private void init(Context context, AttributeSet attributeSet) {
         mColorDisabled = getColor(android.R.color.darker_gray);
         mType = TYPE_NORMAL;
         mShadow = true;
+        mSize = -1;
         mScrollThreshold = getResources().getDimensionPixelOffset(R.dimen.fab_scroll_threshold);
-        mShadowSize = getDimension(R.dimen.fab_shadow_size);
+
         if (attributeSet != null) {
             initAttributes(context, attributeSet);
         }
+
+        calculateSize();
+        calculateShadowSize();
         updateBackground();
     }
 
@@ -119,12 +124,30 @@ private void initAttributes(Context context, AttributeSet attributeSet) {
                     mColorDisabled);
                 mShadow = attr.getBoolean(R.styleable.FloatingActionButton_fab_shadow, true);
                 mType = attr.getInt(R.styleable.FloatingActionButton_fab_type, TYPE_NORMAL);
+
+                // TYPE_MINI overrides any custom size
+                if(mType == TYPE_NORMAL) {
+                    mSize = attr.getDimensionPixelSize(R.styleable.FloatingActionButton_fab_size, mSize);
+                }
             } finally {
                 attr.recycle();
             }
         }
     }
 
+    private void calculateSize() {
+        mSize = mSize == -1 ? getDefaultSize() : mSize;
+    }
+
+    private int getDefaultSize() {
+        return getDimension(mType == TYPE_NORMAL ? R.dimen.fab_size_normal : R.dimen.fab_size_mini);
+    }
+
+    private void calculateShadowSize() {
+        // custom shadow size for TYPE_NORMAL only, TYPE_MINI gets default shadow size
+        mShadowSize =  (mType == TYPE_NORMAL) ? (int)(SHADOW_SIZE_RELATIVE * mSize) : getDimension(R.dimen.fab_shadow_size);
+    }
+
     private void updateBackground() {
         StateListDrawable drawable = new StateListDrawable();
         drawable.addState(new int[]{android.R.attr.state_pressed}, createDrawable(mColorPressed));
@@ -194,9 +217,7 @@ private void setBackgroundCompat(Drawable drawable) {
             setOutlineProvider(new ViewOutlineProvider() {
                 @Override
                 public void getOutline(View view, Outline outline) {
-                    int size = getDimension(mType == TYPE_NORMAL ? R.dimen.fab_size_normal
-                        : R.dimen.fab_size_mini);
-                    outline.setOval(0, 0, size, size);
+                    outline.setOval(0, 0, mSize, mSize);
                 }
             });
             setClipToOutline(true);
diff --git a/library/src/main/res/values/attrs.xml b/library/src/main/res/values/attrs.xml
index 792f37f3..5803275f 100644
--- a/library/src/main/res/values/attrs.xml
+++ b/library/src/main/res/values/attrs.xml
@@ -7,6 +7,7 @@
         <attr name="fab_colorRipple" format="color" />
         <attr name="fab_colorDisabled" format="color" />
         <attr name="fab_shadow" format="boolean" />
+        <attr name="fab_size" format="dimension" />
         <attr name="fab_type" format="enum">
             <enum name="normal" value="0" />
             <enum name="mini" value="1" />