diff --git a/WebARKit/WebARKitCamera.cpp b/WebARKit/WebARKitCamera.cpp
index e4893d4..98b4006 100644
--- a/WebARKit/WebARKitCamera.cpp
+++ b/WebARKit/WebARKitCamera.cpp
@@ -13,10 +13,8 @@ bool WebARKitCamera::setupCamera(int width, int height) {
     }
     xsize = width;
     ysize = height;
-    // simple routine to calculate focal length from diagonal field of view, and convert to camera matrix.
-    diagonal_image_size = std::pow(std::pow(xsize, 2.0) + std::pow(ysize, 2.0), 0.5);
-    diagonal_fov_radians = diagonal_fov_degrees * m_pi / 180.0;
-    focal_length = 0.5 * diagonal_image_size / std::tan(0.5 * diagonal_fov_radians);
+
+    setFocalLength(xsize, ysize);
 
     cmat.at(0) = focal_length;
     cmat.at(2) = 0.5 * xsize;
@@ -42,4 +40,13 @@ std::array<double, 9> WebARKitCamera::getCameraData() const {
 std::array<double, 6> WebARKitCamera::getDistortionCoefficients() const {
    return kc;
 }
+
+void WebARKitCamera::setFocalLength(int width, int height) {
+    double diagonal_image_size;
+    double diagonal_fov_radians;
+     // simple routine to calculate focal length from diagonal field of view, and convert to camera matrix.
+    diagonal_image_size = std::pow(std::pow(width, 2.0) + std::pow(height, 2.0), 0.5);
+    diagonal_fov_radians = diagonal_fov_degrees * m_pi / 180.0;
+    focal_length = 0.5 * diagonal_image_size / std::tan(0.5 * diagonal_fov_radians);
+}
 } // namespace webarkit
\ No newline at end of file
diff --git a/WebARKit/include/WebARKitCamera.h b/WebARKit/include/WebARKitCamera.h
index 98824c1..33b65f6 100644
--- a/WebARKit/include/WebARKitCamera.h
+++ b/WebARKit/include/WebARKitCamera.h
@@ -17,14 +17,16 @@ class WebARKitCamera {
 
     std::array<double, 6> getDistortionCoefficients() const;
 
+    double getFocalLength() const { return focal_length; }
+
   private:
     int xsize, ysize;
     std::array<double, 9> cmat;
     std::array<double, 6> kc;
     double focal_length;
-    double diagonal_image_size;
     double diagonal_fov_degrees;
-    double diagonal_fov_radians;
+
+    void setFocalLength(int width, int height);
 };
 } // namespace webarkit
 
diff --git a/tests/webarkit_test.cc b/tests/webarkit_test.cc
index e829673..6f7b692 100644
--- a/tests/webarkit_test.cc
+++ b/tests/webarkit_test.cc
@@ -78,6 +78,7 @@ TEST(WebARKitCameraTest, TestCamera) {
   EXPECT_EQ(camera_mat[4], 571.25920269684582);
   EXPECT_EQ(camera_mat[5], 240.0);
   EXPECT_EQ(camera_mat[8], 1.0);
+  EXPECT_EQ(camera.getFocalLength(), 571.25920269684582);
   camera.printSettings();
 }