diff --git a/src/cdk/coercion/css-pixel-value.spec.ts b/src/cdk/coercion/css-pixel-value.spec.ts
new file mode 100644
index 000000000000..a3706921547d
--- /dev/null
+++ b/src/cdk/coercion/css-pixel-value.spec.ts
@@ -0,0 +1,19 @@
+import {coerceCssPixelValue} from './css-pixel-value';
+
+describe('coerceCssPixelValue', () => {
+  it('should add pixel units to a number value', () => {
+    expect(coerceCssPixelValue(1337)).toBe('1337px');
+  });
+
+  it('should ignore string values', () => {
+    expect(coerceCssPixelValue('1337rem')).toBe('1337rem');
+  });
+
+  it('should return an empty string for null', () => {
+    expect(coerceCssPixelValue(null)).toBe('');
+  });
+
+  it('should return an empty string for undefined', () => {
+    expect(coerceCssPixelValue(undefined)).toBe('');
+  });
+});
diff --git a/src/cdk/coercion/css-pixel-value.ts b/src/cdk/coercion/css-pixel-value.ts
new file mode 100644
index 000000000000..195110d3e230
--- /dev/null
+++ b/src/cdk/coercion/css-pixel-value.ts
@@ -0,0 +1,16 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+/** Coerces a value to a CSS pixel value. */
+export function coerceCssPixelValue(value: any): string {
+  if (value == null) {
+    return '';
+  }
+
+  return typeof value === 'string' ? value : `${value}px`;
+}
diff --git a/src/cdk/coercion/public-api.ts b/src/cdk/coercion/public-api.ts
index aa2fd160b1ab..6563d2bfab05 100644
--- a/src/cdk/coercion/public-api.ts
+++ b/src/cdk/coercion/public-api.ts
@@ -9,3 +9,4 @@
 export * from './boolean-property';
 export * from './number-property';
 export * from './array';
+export * from './css-pixel-value';
diff --git a/src/cdk/overlay/overlay-ref.ts b/src/cdk/overlay/overlay-ref.ts
index cd8ff411d415..83eb45f9c665 100644
--- a/src/cdk/overlay/overlay-ref.ts
+++ b/src/cdk/overlay/overlay-ref.ts
@@ -13,6 +13,7 @@ import {Observable, Subject} from 'rxjs';
 import {take} from 'rxjs/operators';
 import {OverlayKeyboardDispatcher} from './keyboard/overlay-keyboard-dispatcher';
 import {OverlayConfig} from './overlay-config';
+import {coerceCssPixelValue} from '@angular/cdk/coercion';
 
 
 /** An object where all of its properties cannot be written. */
@@ -254,27 +255,27 @@ export class OverlayRef implements PortalOutlet {
   /** Updates the size of the overlay element based on the overlay config. */
   private _updateElementSize() {
     if (this._config.width || this._config.width === 0) {
-      this._pane.style.width = formatCssUnit(this._config.width);
+      this._pane.style.width = coerceCssPixelValue(this._config.width);
     }
 
     if (this._config.height || this._config.height === 0) {
-      this._pane.style.height = formatCssUnit(this._config.height);
+      this._pane.style.height = coerceCssPixelValue(this._config.height);
     }
 
     if (this._config.minWidth || this._config.minWidth === 0) {
-      this._pane.style.minWidth = formatCssUnit(this._config.minWidth);
+      this._pane.style.minWidth = coerceCssPixelValue(this._config.minWidth);
     }
 
     if (this._config.minHeight || this._config.minHeight === 0) {
-      this._pane.style.minHeight = formatCssUnit(this._config.minHeight);
+      this._pane.style.minHeight = coerceCssPixelValue(this._config.minHeight);
     }
 
     if (this._config.maxWidth || this._config.maxWidth === 0) {
-      this._pane.style.maxWidth = formatCssUnit(this._config.maxWidth);
+      this._pane.style.maxWidth = coerceCssPixelValue(this._config.maxWidth);
     }
 
     if (this._config.maxHeight || this._config.maxHeight === 0) {
-      this._pane.style.maxHeight = formatCssUnit(this._config.maxHeight);
+      this._pane.style.maxHeight = coerceCssPixelValue(this._config.maxHeight);
     }
   }
 
@@ -369,10 +370,6 @@ export class OverlayRef implements PortalOutlet {
   }
 }
 
-function formatCssUnit(value: number | string) {
-  return typeof value === 'string' ? value as string : `${value}px`;
-}
-
 
 /** Size properties for an overlay. */
 export interface OverlaySizeConfig {
diff --git a/src/cdk/overlay/position/flexible-connected-position-strategy.ts b/src/cdk/overlay/position/flexible-connected-position-strategy.ts
index 4792318a89d4..76ced6f3762b 100644
--- a/src/cdk/overlay/position/flexible-connected-position-strategy.ts
+++ b/src/cdk/overlay/position/flexible-connected-position-strategy.ts
@@ -17,6 +17,7 @@ import {
 import {Observable, Subscription, Subject} from 'rxjs';
 import {OverlayRef} from '../overlay-ref';
 import {isElementScrolledOutsideView, isElementClippedByScrolling} from './scroll-clip';
+import {coerceCssPixelValue} from '@angular/cdk/coercion';
 
 
 // TODO: refactor clipping detection into a separate thing (part of scrolling module)
@@ -665,9 +666,9 @@ export class FlexibleConnectedPositionStrategy implements PositionStrategy {
       styles.bottom = '';
       styles.height = '100%';
     } else {
-      styles.height = `${boundingBoxRect.height}px`;
-      styles.top = boundingBoxRect.top != null ? `${boundingBoxRect.top}px` : '';
-      styles.bottom = boundingBoxRect.bottom != null ? `${boundingBoxRect.bottom}px` : '';
+      styles.top = coerceCssPixelValue(boundingBoxRect.top);
+      styles.bottom = coerceCssPixelValue(boundingBoxRect.bottom);
+      styles.height = coerceCssPixelValue(boundingBoxRect.height);
     }
 
     if (!this._hasFlexibleWidth || this._isPushed) {
@@ -675,19 +676,19 @@ export class FlexibleConnectedPositionStrategy implements PositionStrategy {
       styles.right = '';
       styles.width = '100%';
     } else {
-      styles.width = `${boundingBoxRect.width}px`;
-      styles.left = boundingBoxRect.left != null ? `${boundingBoxRect.left}px` : '';
-      styles.right = boundingBoxRect.right != null ? `${boundingBoxRect.right}px` : '';
+      styles.left = coerceCssPixelValue(boundingBoxRect.left);
+      styles.right = coerceCssPixelValue(boundingBoxRect.right);
+      styles.width = coerceCssPixelValue(boundingBoxRect.width);
     }
 
     const maxHeight = this._overlayRef.getConfig().maxHeight;
     if (maxHeight && this._hasFlexibleHeight) {
-      styles.maxHeight = formatCssUnit(maxHeight);
+      styles.maxHeight = coerceCssPixelValue(maxHeight);
     }
 
     const maxWidth = this._overlayRef.getConfig().maxWidth;
     if (maxWidth && this._hasFlexibleWidth) {
-      styles.maxWidth = formatCssUnit(maxWidth);
+      styles.maxWidth = coerceCssPixelValue(maxWidth);
     }
 
     this._lastBoundingBoxSize = boundingBoxRect;
@@ -800,7 +801,7 @@ export class FlexibleConnectedPositionStrategy implements PositionStrategy {
       const documentHeight = this._document.documentElement.clientHeight;
       styles.bottom = `${documentHeight - (overlayPoint.y + this._overlayRect.height)}px`;
     } else {
-      styles.top = `${overlayPoint.y}px`;
+      styles.top = coerceCssPixelValue(overlayPoint.y);
     }
 
     return styles;
@@ -835,7 +836,7 @@ export class FlexibleConnectedPositionStrategy implements PositionStrategy {
       const documentWidth = this._document.documentElement.clientWidth;
       styles.right = `${documentWidth - (overlayPoint.x + this._overlayRect.width)}px`;
     } else {
-      styles.left = `${overlayPoint.x}px`;
+      styles.left = coerceCssPixelValue(overlayPoint.x);
     }
 
     return styles;
@@ -971,11 +972,6 @@ export interface ConnectedPosition {
   offsetY?: number;
 }
 
-// TODO: move to common place
-function formatCssUnit(value: number | string) {
-  return typeof value === 'string' ? value as string : `${value}px`;
-}
-
 /** Shallow-extends a stylesheet object with another stylesheet object. */
 function extendStyles(dest: CSSStyleDeclaration, source: CSSStyleDeclaration): CSSStyleDeclaration {
   for (let key in source) {
diff --git a/src/cdk/overlay/scroll/block-scroll-strategy.ts b/src/cdk/overlay/scroll/block-scroll-strategy.ts
index 00cd0642e404..5ad36ea2a3e1 100644
--- a/src/cdk/overlay/scroll/block-scroll-strategy.ts
+++ b/src/cdk/overlay/scroll/block-scroll-strategy.ts
@@ -8,6 +8,7 @@
 
 import {ScrollStrategy} from './scroll-strategy';
 import {ViewportRuler} from '@angular/cdk/scrolling';
+import {coerceCssPixelValue} from '@angular/cdk/coercion';
 
 /**
  * Strategy that will prevent the user from scrolling while the overlay is visible.
@@ -38,8 +39,8 @@ export class BlockScrollStrategy implements ScrollStrategy {
 
       // Note: we're using the `html` node, instead of the `body`, because the `body` may
       // have the user agent margin, whereas the `html` is guaranteed not to have one.
-      root.style.left = `${-this._previousScrollPosition.left}px`;
-      root.style.top = `${-this._previousScrollPosition.top}px`;
+      root.style.left = coerceCssPixelValue(-this._previousScrollPosition.left);
+      root.style.top = coerceCssPixelValue(-this._previousScrollPosition.top);
       root.classList.add('cdk-global-scrollblock');
       this._isEnabled = true;
     }