diff --git a/src/lib/progress-spinner/progress-spinner.spec.ts b/src/lib/progress-spinner/progress-spinner.spec.ts
index 5aff4b509922..5c9c758f69ab 100644
--- a/src/lib/progress-spinner/progress-spinner.spec.ts
+++ b/src/lib/progress-spinner/progress-spinner.spec.ts
@@ -17,6 +17,7 @@ describe('MatProgressSpinner', () => {
         ProgressSpinnerCustomStrokeWidth,
         ProgressSpinnerCustomDiameter,
         SpinnerWithColor,
+        ProgressSpinnerWithStringValues,
       ],
     }).compileComponents();
   }));
@@ -184,6 +185,24 @@ describe('MatProgressSpinner', () => {
     expect(fixture.nativeElement.querySelector('svg').getAttribute('focusable')).toBe('false');
   });
 
+  it('should handle the number inputs being passed in as strings', () => {
+    const fixture = TestBed.createComponent(ProgressSpinnerWithStringValues);
+    const spinner = fixture.debugElement.query(By.directive(MatProgressSpinner));
+    const svgElement = spinner.nativeElement.querySelector('svg');
+
+    fixture.detectChanges();
+
+    expect(spinner.componentInstance.diameter).toBe(37);
+    expect(spinner.componentInstance.strokeWidth).toBe(11);
+    expect(spinner.componentInstance.value).toBe(25);
+
+    expect(spinner.nativeElement.style.width).toBe('38px');
+    expect(spinner.nativeElement.style.height).toBe('38px');
+    expect(svgElement.style.width).toBe('38px');
+    expect(svgElement.style.height).toBe('38px');
+    expect(svgElement.getAttribute('viewBox')).toBe('0 0 38 38');
+  });
+
 });
 
 
@@ -211,3 +230,10 @@ class SpinnerWithColor { color: string = 'primary'; }
 
 @Component({template: `<mat-progress-spinner value="50" [color]="color"></mat-progress-spinner>`})
 class ProgressSpinnerWithColor { color: string = 'primary'; }
+
+@Component({
+  template: `
+    <mat-progress-spinner value="25" diameter="37" strokeWidth="11"></mat-progress-spinner>
+  `
+})
+class ProgressSpinnerWithStringValues { }
diff --git a/src/lib/progress-spinner/progress-spinner.ts b/src/lib/progress-spinner/progress-spinner.ts
index f2c55071e1b7..c4db3d0016ef 100644
--- a/src/lib/progress-spinner/progress-spinner.ts
+++ b/src/lib/progress-spinner/progress-spinner.ts
@@ -26,6 +26,18 @@ import {coerceNumberProperty} from '@angular/cdk/coercion';
 /** Possible mode for a progress spinner. */
 export type ProgressSpinnerMode = 'determinate' | 'indeterminate';
 
+/**
+ * Base reference size of the spinner.
+ * @docs-private
+ */
+const BASE_SIZE = 100;
+
+/**
+ * Base reference stroke width of the spinner.
+ * @docs-private
+ */
+const BASE_STROKE_WIDTH = 10;
+
 // Boilerplate for applying mixins to MatProgressSpinner.
 /** @docs-private */
 export class MatProgressSpinnerBase {
@@ -84,17 +96,15 @@ const INDETERMINATE_ANIMATION_TEMPLATE = `
 export class MatProgressSpinner extends _MatProgressSpinnerMixinBase implements CanColor,
   OnChanges {
 
-  private _value: number = 0;
-  private readonly _baseSize = 100;
-  private readonly _baseStrokeWidth = 10;
-  private _fallbackAnimation = false;
+  private _value = 0;
   private _strokeWidth: number;
+  private _fallbackAnimation = false;
 
   /** The width and height of the host element. Will grow with stroke width. **/
-  _elementSize = this._baseSize;
+  _elementSize = BASE_SIZE;
 
   /** Tracks diameters of existing instances to de-dupe generated styles (default d = 100) */
-  private static diameters = new Set<number>([100]);
+  private static diameters = new Set<number>([BASE_SIZE]);
 
   /**
    * Used for storing all of the generated keyframe animations.
@@ -107,11 +117,14 @@ export class MatProgressSpinner extends _MatProgressSpinnerMixinBase implements
   get diameter(): number {
     return this._diameter;
   }
-
   set diameter(size: number) {
-    this._setDiameterAndInitStyles(size);
+    this._diameter = coerceNumberProperty(size);
+
+    if (!this._fallbackAnimation && !MatProgressSpinner.diameters.has(this._diameter)) {
+      this._attachStyleNode();
+    }
   }
-  _diameter = this._baseSize;
+  private _diameter = BASE_SIZE;
 
   /** Stroke width of the progress spinner. */
   @Input()
@@ -134,7 +147,7 @@ export class MatProgressSpinner extends _MatProgressSpinnerMixinBase implements
   }
   set value(newValue: number) {
     if (newValue != null && this.mode === 'determinate') {
-      this._value = Math.max(0, Math.min(100, newValue));
+      this._value = Math.max(0, Math.min(100, coerceNumberProperty(newValue)));
     }
   }
 
@@ -154,14 +167,13 @@ export class MatProgressSpinner extends _MatProgressSpinnerMixinBase implements
 
   ngOnChanges(changes: SimpleChanges) {
     if (changes.strokeWidth || changes.diameter) {
-      this._elementSize =
-          this._diameter + Math.max(this.strokeWidth - this._baseStrokeWidth, 0);
+      this._elementSize = this._diameter + Math.max(this.strokeWidth - BASE_STROKE_WIDTH, 0);
     }
   }
 
   /** The radius of the spinner, adjusted for stroke width. */
   get _circleRadius() {
-    return (this.diameter - this._baseStrokeWidth) / 2;
+    return (this.diameter - BASE_STROKE_WIDTH) / 2;
   }
 
   /** The view box of the spinner's svg element. */
@@ -194,14 +206,6 @@ export class MatProgressSpinner extends _MatProgressSpinnerMixinBase implements
     return this.strokeWidth / this._elementSize * 100;
   }
 
-  /** Sets the diameter and adds diameter-specific styles if necessary. */
-  private _setDiameterAndInitStyles(size: number): void {
-    this._diameter = size;
-    if (!MatProgressSpinner.diameters.has(this.diameter) && !this._fallbackAnimation) {
-      this._attachStyleNode();
-    }
-  }
-
   /** Dynamically generates a style tag containing the correct animation for this diameter. */
   private _attachStyleNode(): void {
     let styleTag = MatProgressSpinner.styleTag;
diff --git a/src/lib/select/select.spec.ts b/src/lib/select/select.spec.ts
index 45cb03cf0c59..a58f331646b7 100644
--- a/src/lib/select/select.spec.ts
+++ b/src/lib/select/select.spec.ts
@@ -1870,7 +1870,6 @@ describe('MatSelect', () => {
 
         // There appears to be a small rounding error on IE, so we verify that the value is close,
         // not exact.
-        let platform = new Platform();
         if (platform.TRIDENT) {
           let difference =
               Math.abs(optionTop + (menuItemHeight - triggerHeight) / 2 - triggerTop);