--- a/gfx/layers/apz/src/AsyncPanZoomController.cpp
+++ b/gfx/layers/apz/src/AsyncPanZoomController.cpp
@@ -64,16 +64,17 @@
 #include "nsDebug.h"                    // for NS_WARNING
 #include "nsIDOMWindowUtils.h"          // for nsIDOMWindowUtils
 #include "nsMathUtils.h"                // for NS_hypot
 #include "nsPoint.h"                    // for nsIntPoint
 #include "nsStyleConsts.h"
 #include "nsStyleStruct.h"              // for nsTimingFunction
 #include "nsTArray.h"                   // for nsTArray, nsTArray_Impl, etc
 #include "nsThreadUtils.h"              // for NS_IsMainThread
+#include "nsViewportInfo.h"             // for kViewportMinScale, kViewportMaxScale
 #include "prsystem.h"                   // for PR_GetPhysicalMemorySize
 #include "SharedMemoryBasic.h"          // for SharedMemoryBasic
 #include "ScrollSnap.h"                 // for ScrollSnapUtils
 #include "WheelScrollAnimation.h"
 #if defined(MOZ_ANDROID_APZ)
 #include "AndroidAPZ.h"
 #endif // defined(MOZ_ANDROID_APZ)
 
@@ -395,26 +396,16 @@ static const double kDefaultEstimatedPai
  */
 static bool gIsHighMemSystem = false;
 static bool IsHighMemSystem()
 {
   return gIsHighMemSystem;
 }
 
 /**
- * Maximum zoom amount, always used, even if a page asks for higher.
- */
-static const CSSToParentLayerScale MAX_ZOOM(8.0f);
-
-/**
- * Minimum zoom amount, always used, even if a page asks for lower.
- */
-static const CSSToParentLayerScale MIN_ZOOM(0.125f);
-
-/**
  * Is aAngle within the given threshold of the horizontal axis?
  * @param aAngle an angle in radians in the range [0, pi]
  * @param aThreshold an angle in radians in the range [0, pi/2]
  */
 static bool IsCloseToHorizontal(float aAngle, float aThreshold)
 {
   return (aAngle < aThreshold || aAngle > (M_PI - aThreshold));
 }
@@ -697,17 +688,19 @@ AsyncPanZoomController::AsyncPanZoomCont
      mTreeManager(aTreeManager),
      mSharingFrameMetricsAcrossProcesses(false),
      mFrameMetrics(mScrollMetadata.GetMetrics()),
      mMonitor("AsyncPanZoomController"),
      mLastContentPaintMetrics(mLastContentPaintMetadata.GetMetrics()),
      mX(this),
      mY(this),
      mPanDirRestricted(false),
-     mZoomConstraints(false, false, MIN_ZOOM, MAX_ZOOM),
+     mZoomConstraints(false, false,
+        mFrameMetrics.GetDevPixelsPerCSSPixel() * kViewportMinScale / ParentLayerToScreenScale(1),
+        mFrameMetrics.GetDevPixelsPerCSSPixel() * kViewportMaxScale / ParentLayerToScreenScale(1)),
      mLastSampleTime(GetFrameTime()),
      mLastCheckerboardReport(GetFrameTime()),
      mOverscrollEffect(MakeUnique<OverscrollEffect>(*this)),
      mState(NOTHING),
      mNotificationBlockers(0),
      mInputQueue(aInputQueue),
      mPinchPaintTimerSet(false),
      mAPZCId(sAsyncPanZoomControllerCount++),
@@ -3670,21 +3663,27 @@ bool AsyncPanZoomController::IsInPanning
 
 void AsyncPanZoomController::UpdateZoomConstraints(const ZoomConstraints& aConstraints) {
   APZC_LOG("%p updating zoom constraints to %d %d %f %f\n", this, aConstraints.mAllowZoom,
     aConstraints.mAllowDoubleTapZoom, aConstraints.mMinZoom.scale, aConstraints.mMaxZoom.scale);
   if (IsNaN(aConstraints.mMinZoom.scale) || IsNaN(aConstraints.mMaxZoom.scale)) {
     NS_WARNING("APZC received zoom constraints with NaN values; dropping...");
     return;
   }
+
+  CSSToParentLayerScale min = mFrameMetrics.GetDevPixelsPerCSSPixel()
+    * kViewportMinScale / ParentLayerToScreenScale(1);
+  CSSToParentLayerScale max = mFrameMetrics.GetDevPixelsPerCSSPixel()
+    * kViewportMaxScale / ParentLayerToScreenScale(1);
+
   // inf float values and other bad cases should be sanitized by the code below.
   mZoomConstraints.mAllowZoom = aConstraints.mAllowZoom;
   mZoomConstraints.mAllowDoubleTapZoom = aConstraints.mAllowDoubleTapZoom;
-  mZoomConstraints.mMinZoom = (MIN_ZOOM > aConstraints.mMinZoom ? MIN_ZOOM : aConstraints.mMinZoom);
-  mZoomConstraints.mMaxZoom = (MAX_ZOOM > aConstraints.mMaxZoom ? aConstraints.mMaxZoom : MAX_ZOOM);
+  mZoomConstraints.mMinZoom = (min > aConstraints.mMinZoom ? min : aConstraints.mMinZoom);
+  mZoomConstraints.mMaxZoom = (max > aConstraints.mMaxZoom ? aConstraints.mMaxZoom : max);
   if (mZoomConstraints.mMaxZoom < mZoomConstraints.mMinZoom) {
     mZoomConstraints.mMaxZoom = mZoomConstraints.mMinZoom;
   }
 }
 
 ZoomConstraints
 AsyncPanZoomController::GetZoomConstraints() const
 {