diff --git a/packages/netlify-cms-widget-number/src/NumberControl.js b/packages/netlify-cms-widget-number/src/NumberControl.js
index 96ddd6e6..e6b314c4 100644
--- a/packages/netlify-cms-widget-number/src/NumberControl.js
+++ b/packages/netlify-cms-widget-number/src/NumberControl.js
@@ -8,6 +8,46 @@ const ValidationErrorTypes = {
   CUSTOM: 'CUSTOM',
 };
 
+export function validateMinMax(value, min, max, field, t) {
+  let error;
+
+  switch (true) {
+    case value !== '' && 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 value !== '' && 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 value !== '' && 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:
+      error = null;
+      break;
+  }
+
+  return error;
+}
+
 export default class NumberControl extends React.Component {
   static propTypes = {
     field: ImmutablePropTypes.map.isRequired,
@@ -45,47 +85,14 @@ export default class NumberControl extends React.Component {
     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 };
+    const error = validateMinMax(value, min, max, field, t);
+    return error ? { error } : true;
   };
 
   render() {
diff --git a/packages/netlify-cms-widget-number/src/__tests__/number.spec.js b/packages/netlify-cms-widget-number/src/__tests__/number.spec.js
index 4c1663ad..d4610b31 100644
--- a/packages/netlify-cms-widget-number/src/__tests__/number.spec.js
+++ b/packages/netlify-cms-widget-number/src/__tests__/number.spec.js
@@ -4,6 +4,7 @@ import { render, fireEvent } from 'react-testing-library';
 import 'react-testing-library/cleanup-after-each';
 import 'jest-dom/extend-expect';
 import { NetlifyCmsWidgetNumber } from '../';
+import { validateMinMax } from '../NumberControl';
 
 const NumberControl = NetlifyCmsWidgetNumber.controlComponent;
 
@@ -142,4 +143,73 @@ describe('Number widget', () => {
 
     expect(input.value).toBe('0');
   });
+
+  describe('validateMinMax', () => {
+    const field = { get: jest.fn() };
+    field.get.mockReturnValue('label');
+    const t = jest.fn();
+    t.mockImplementation((_, params) => params);
+
+    beforeEach(() => {
+      jest.clearAllMocks();
+    });
+
+    it('should return error when min max are defined and value is out of range', () => {
+      const error = validateMinMax(5, 0, 1, field, t);
+      const expectedMessage = {
+        fieldLabel: 'label',
+        minValue: 0,
+        maxValue: 1,
+      };
+      expect(error).not.toBeNull();
+      expect(error).toEqual({
+        type: 'RANGE',
+        message: expectedMessage,
+      });
+      expect(t).toHaveBeenCalledTimes(1);
+      expect(t).toHaveBeenCalledWith('editor.editorControlPane.widget.range', expectedMessage);
+    });
+
+    it('should return error when min is defined and value is out of range', () => {
+      const error = validateMinMax(5, 6, false, field, t);
+      const expectedMessage = {
+        fieldLabel: 'label',
+        minValue: 6,
+      };
+      expect(error).not.toBeNull();
+      expect(error).toEqual({
+        type: 'RANGE',
+        message: expectedMessage,
+      });
+      expect(t).toHaveBeenCalledTimes(1);
+      expect(t).toHaveBeenCalledWith('editor.editorControlPane.widget.min', expectedMessage);
+    });
+
+    it('should return error when max is defined and value is out of range', () => {
+      const error = validateMinMax(5, false, 3, field, t);
+      const expectedMessage = {
+        fieldLabel: 'label',
+        maxValue: 3,
+      };
+      expect(error).not.toBeNull();
+      expect(error).toEqual({
+        type: 'RANGE',
+        message: expectedMessage,
+      });
+      expect(t).toHaveBeenCalledTimes(1);
+      expect(t).toHaveBeenCalledWith('editor.editorControlPane.widget.max', expectedMessage);
+    });
+
+    it('should not return error when min max are defined and value is empty', () => {
+      const error = validateMinMax('', 0, 1, field, t);
+
+      expect(error).toBeNull();
+    });
+
+    it('should not return error when min max are defined and value is in range', () => {
+      const error = validateMinMax(0, -1, 1, field, t);
+
+      expect(error).toBeNull();
+    });
+  });
 });