Hardcode Toolbar icon dimension

android/app/src/main/java/com/reactnativenavigation/utils/ImageUtils.java

 package com.reactnativenavigation.utils;
 
+import android.content.Context;
+import android.content.res.Resources;
 import android.graphics.PorterDuff;
 import android.graphics.PorterDuffColorFilter;
 import android.graphics.drawable.Drawable;
+import android.util.DisplayMetrics;
 
 /**
  * Created by guyc on 23/04/16.
         drawable.setColorFilter(new PorterDuffColorFilter(tint, PorterDuff.Mode.SRC_IN));
     }
 
+    /**
+     * This method converts dp unit to equivalent pixels, depending on device density.
+     *
+     * @param dp A value in dp (density independent pixels) unit. Which we need to convert into pixels
+     * @param context Context to get resources and device specific display metrics
+     * @return A float value to represent px equivalent to dp depending on device density
+     */
+    public static float convertDpToPixel(float dp, Context context){
+        Resources resources = context.getResources();
+        DisplayMetrics metrics = resources.getDisplayMetrics();
+        float px = dp * ((float)metrics.densityDpi / DisplayMetrics.DENSITY_DEFAULT);
+        return px;
+    }
 }

android/app/src/main/java/com/reactnativenavigation/views/RnnToolBar.java

             mOldButtons = oldScreen == null ? null : oldScreen.getButtons();
             mNewButtons = newScreen.getButtons();
             mTintColor = newScreen.navBarButtonColor;
-            mIconDimensions = (int) (toolBar.getHeight() * 0.4f);
+            mIconDimensions = (int) ImageUtils.convertDpToPixel(48, toolBar.getContext());
         }
 
         @Override