diff --git a/README.md b/README.md
index 00c42c0..0ebb34f 100644
--- a/README.md
+++ b/README.md
@@ -88,6 +88,17 @@ var os = new OnScreen({
 The instance, `os`, has the following options:
 
 `options.tolerance` is the number of pixels an element is allowed to enter its container boundaries before calling its callback. Defaults to `0`.
+May be configured as a number which will be used for all boundaries or as an object containing tolerance values for each boundary. Missing property values also default to `0`.
+```javascript
+var os = new OnScreen({
+    tolerance: {
+        top: 10,
+        right: 20,
+        bottom: 30,
+        left: 40
+    }
+});
+```
 
 `options.debounce` is the number of milliseconds to wait before calling an element's callback after the user has stopped scrolling. Defaults to `100`.
 
diff --git a/lib/helpers/in-container.js b/lib/helpers/in-container.js
index b2d89d7..51748a7 100644
--- a/lib/helpers/in-container.js
+++ b/lib/helpers/in-container.js
@@ -5,7 +5,9 @@
  * @param {node} element The DOM node you want to check
  * @return {boolean} A boolean value that indicates wether is on or off the container.
  */
-function inContainer(el, options = { tolerance: 0, container: '' }) {
+function inContainer(el,
+                     options = { tolerance: { top: 0, right: 0, bottom: 0, left: 0 },
+                     container: '' }) {
     if (!el) {
         throw new Error('You should specify the element you want to test');
     }
@@ -15,7 +17,7 @@ function inContainer(el, options = { tolerance: 0, container: '' }) {
     }
     if (typeof options === 'string') {
         options = {
-            tolerance: 0,
+            tolerance: { top: 0, right: 0, bottom: 0, left: 0 },
             container: document.querySelector(options)
         };
     }
@@ -24,7 +26,7 @@ function inContainer(el, options = { tolerance: 0, container: '' }) {
     }
     if (options instanceof HTMLElement) {
         options = {
-            tolerance: 0,
+            tolerance: { top: 0, right: 0, bottom: 0, left: 0 },
             container: options
         };
     }
@@ -36,19 +38,19 @@ function inContainer(el, options = { tolerance: 0, container: '' }) {
 
     return (
         // // Check bottom boundary
-        (el.offsetTop + el.clientHeight) - options.tolerance >
+        (el.offsetTop + el.clientHeight) - options.tolerance.bottom >
         options.container.scrollTop &&
 
         // Check right boundary
-        (el.offsetLeft + el.clientWidth) - options.tolerance >
+        (el.offsetLeft + el.clientWidth) - options.tolerance.right >
         options.container.scrollLeft &&
 
         // Check left boundary
-        el.offsetLeft + options.tolerance <
+        el.offsetLeft + options.tolerance.left <
         containerRect.width + options.container.scrollLeft &&
 
         // // Check top boundary
-        el.offsetTop + options.tolerance <
+        el.offsetTop + options.tolerance.top <
         containerRect.height + options.container.scrollTop
     );
 }
diff --git a/lib/helpers/in-viewport.js b/lib/helpers/in-viewport.js
index 883a628..2d3fb04 100644
--- a/lib/helpers/in-viewport.js
+++ b/lib/helpers/in-viewport.js
@@ -5,7 +5,7 @@
  * @param {node} element The DOM node you want to check
  * @return {boolean} A boolean value that indicates wether is on or off the viewport.
  */
-function inViewport(el, options = { tolerance: 0 }) {
+function inViewport(el, options = { tolerance: { top: 0, right: 0, bottom: 0, left: 0 } }) {
     if (!el) {
         throw new Error('You should specify the element you want to test');
     }
@@ -18,17 +18,17 @@ function inViewport(el, options = { tolerance: 0 }) {
 
     return (
         // Check bottom boundary
-        elRect.bottom - options.tolerance > 0 &&
+        elRect.bottom - options.tolerance.bottom > 0 &&
 
         // Check right boundary
-        elRect.right - options.tolerance > 0 &&
+        elRect.right - options.tolerance.right > 0 &&
 
         // Check left boundary
-        elRect.left + options.tolerance < (window.innerWidth ||
+        elRect.left + options.tolerance.left < (window.innerWidth ||
         document.documentElement.clientWidth) &&
 
         // Check top boundary
-        elRect.top + options.tolerance < (window.innerHeight ||
+        elRect.top + options.tolerance.top < (window.innerHeight ||
         document.documentElement.clientHeight)
     );
 }
diff --git a/lib/index.js b/lib/index.js
index 8c0cc7f..9161e4b 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -48,10 +48,39 @@ function OnScreen(options = { tolerance: 0, debounce: 100, container: window })
         },
         tolerance: {
             get() {
-                return parseInt(options.tolerance, 10) || 0;
+                if (typeof options.tolerance === 'number') {
+                    const tolerance = parseInt(options.tolerance, 10) || 0;
+                    return {
+                        top: tolerance,
+                        right: tolerance,
+                        bottom: tolerance,
+                        left: tolerance
+                    };
+                }
+
+                return {
+                    top: parseInt(options.tolerance.top, 10) || 0,
+                    right: parseInt(options.tolerance.right, 10) || 0,
+                    bottom: parseInt(options.tolerance.bottom, 10) || 0,
+                    left: parseInt(options.tolerance.left, 10) || 0
+                };
             },
             set(value) {
-                options.tolerance = value;
+                if (typeof value === 'number') {
+                    options.tolerance = {
+                        top: value,
+                        right: value,
+                        bottom: value,
+                        left: value
+                    };
+                } else {
+                    options.tolerance = {
+                        top: value.top || 0,
+                        right: value.right || 0,
+                        bottom: value.bottom || 0,
+                        left: value.left || 0
+                    };
+                }
             }
         }
     });
diff --git a/test/index_test.js b/test/index_test.js
index baba109..4a0c402 100644
--- a/test/index_test.js
+++ b/test/index_test.js
@@ -6,17 +6,65 @@ describe('Instantiation', () => {
     it('should create an instance with default settings', () => {
         const instance = new OnScreen();
 
-        expect(instance.options.tolerance).to.equal(0);
+        ['top', 'right', 'bottom', 'left'].forEach((prop) => {
+            expect(instance.options.tolerance[prop]).to.equal(0);
+        });
         expect(instance.options.debounce).to.equal(100);
     });
 
-    it('should create an instance with custom settings', () => {
+    it('should create an instance with custom settings and single tolerance value', () => {
         const instance = new OnScreen({
             tolerance: 50,
             debounce: 50
         });
 
-        expect(instance.options.tolerance).to.equal(50);
+        ['top', 'right', 'bottom', 'left'].forEach((prop) => {
+            expect(instance.options.tolerance[prop]).to.equal(50);
+        });
+        expect(instance.options.debounce).to.equal(50);
+    });
+
+    it('should create an instance with custom settings and multiple tolerance values', () => {
+        const instance = new OnScreen({
+            tolerance: {
+                top: 150,
+                right: 250,
+                bottom: 350,
+                left: 450
+            },
+            debounce: 50
+        });
+
+        const expectedTolerances = {
+            top: 150,
+            right: 250,
+            bottom: 350,
+            left: 450
+        };
+        ['top', 'right', 'bottom', 'left'].forEach((prop) => {
+            expect(instance.options.tolerance[prop]).to.equal(expectedTolerances[prop]);
+        });
+        expect(instance.options.debounce).to.equal(50);
+    });
+
+    it('should create an instance with custom settings and some tolerances missing', () => {
+        const instance = new OnScreen({
+            tolerance: {
+                top: 150,
+                right: 250
+            },
+            debounce: 50
+        });
+
+        const expectedTolerances = {
+            top: 150,
+            right: 250,
+            bottom: 0,
+            left: 0
+        };
+        ['top', 'right', 'bottom', 'left'].forEach((prop) => {
+            expect(instance.options.tolerance[prop]).to.equal(expectedTolerances[prop]);
+        });
         expect(instance.options.debounce).to.equal(50);
     });
 });