diff --git a/packages/netlify-cms-core/src/constants/defaultPhrases.js b/packages/netlify-cms-core/src/constants/defaultPhrases.js
index 79114de0..ebae7694 100644
--- a/packages/netlify-cms-core/src/constants/defaultPhrases.js
+++ b/packages/netlify-cms-core/src/constants/defaultPhrases.js
@@ -39,6 +39,9 @@ export function getPhrases() {
           required: '%{fieldLabel} is required.',
           regexPattern: "%{fieldLabel} didn't match the pattern: %{pattern}.",
           processing: '%{fieldLabel} is processing.',
+          range: '%{fieldLabel} must be between %{minValue} and %{maxValue}.',
+          min: '%{fieldLabel} must be at least %{minValue}.',
+          max: '%{fieldLabel} must be %{maxValue} or less.',
         },
       },
       editor: {
diff --git a/packages/netlify-cms-core/src/constants/validationErrorTypes.js b/packages/netlify-cms-core/src/constants/validationErrorTypes.js
index 2305209c..b29adddb 100644
--- a/packages/netlify-cms-core/src/constants/validationErrorTypes.js
+++ b/packages/netlify-cms-core/src/constants/validationErrorTypes.js
@@ -1,5 +1,6 @@
 export default {
   PRESENCE: 'PRESENCE',
   PATTERN: 'PATTERN',
+  RANGE: 'RANGE',
   CUSTOM: 'CUSTOM',
 };
diff --git a/packages/netlify-cms-widget-number/src/NumberControl.js b/packages/netlify-cms-widget-number/src/NumberControl.js
index c926611e..be6e7c61 100644
--- a/packages/netlify-cms-widget-number/src/NumberControl.js
+++ b/packages/netlify-cms-widget-number/src/NumberControl.js
@@ -1,6 +1,7 @@
 import React from 'react';
 import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
+import ValidationErrorTypes from 'netlify-cms-core/src/constants/validationErrorTypes';
 
 export default class NumberControl extends React.Component {
   static propTypes = {
@@ -15,6 +16,7 @@ export default class NumberControl extends React.Component {
     step: PropTypes.number,
     min: PropTypes.number,
     max: PropTypes.number,
+    t: PropTypes.func.isRequired,
   };
 
   static defaultProps = {
@@ -33,6 +35,54 @@ export default class NumberControl extends React.Component {
     }
   };
 
+  isValid = () => {
+    const { field, value, t } = this.props;
+    const hasPattern = !!field.get('pattern', false);
+    const min = field.get('min', false);
+    const max = field.get('max', false);
+    let error;
+
+    // Pattern overrides min/max logic always:
+    if (hasPattern) {
+      return true;
+    }
+
+    switch (true) {
+      case min !== false && max !== false && (value < min || value > max):
+        error = {
+          type: ValidationErrorTypes.RANGE,
+          message: t('editor.editorControlPane.widget.range', {
+            fieldLabel: field.get('label', field.get('name')),
+            minValue: min,
+            maxValue: max,
+          }),
+        };
+        break;
+      case min !== false && value < min:
+        error = {
+          type: ValidationErrorTypes.RANGE,
+          message: t('editor.editorControlPane.widget.min', {
+            fieldLabel: field.get('label', field.get('name')),
+            minValue: min,
+          }),
+        };
+        break;
+      case max !== false && value > max:
+        error = {
+          type: ValidationErrorTypes.RANGE,
+          message: t('editor.editorControlPane.widget.max', {
+            fieldLabel: field.get('label', field.get('name')),
+            maxValue: max,
+          }),
+        };
+        break;
+      default:
+        return true;
+    }
+
+    return { error };
+  };
+
   render() {
     const { field, value, classNameWrapper, forID, setActiveStyle, setInactiveStyle } = this.props;
     const min = field.get('min', '');
diff --git a/website/content/docs/widgets/number.md b/website/content/docs/widgets/number.md
index 5b9f31ee..88ce191c 100644
--- a/website/content/docs/widgets/number.md
+++ b/website/content/docs/widgets/number.md
@@ -13,6 +13,7 @@ The number widget uses an HTML number input, saving the value as a string, integ
   - `valueType`: accepts `int` or `float`; any other value results in saving as a string
   - `min`: accepts a number for minimum value accepted; unset by default
   - `max`: accepts a number for maximum value accepted; unset by default
+  - `step`: accepts a number for stepping up/down values in the input; 1 by default
 - **Example:**
     ```yaml
     - label: "Puppy Count"
@@ -22,4 +23,5 @@ The number widget uses an HTML number input, saving the value as a string, integ
       valueType: "int"
       min: 1
       max: 101
+      step: 2
     ```