diff --git a/Eigen/src/SparseCore/CompressedStorage.h b/Eigen/src/SparseCore/CompressedStorage.h
index 10d516a66..a667cb56e 100644
--- a/Eigen/src/SparseCore/CompressedStorage.h
+++ b/Eigen/src/SparseCore/CompressedStorage.h
@@ -83,10 +83,10 @@ class CompressedStorage
         reallocate(m_size);
     }
 
-    void resize(size_t size, float reserveSizeFactor = 0)
+    void resize(size_t size, double reserveSizeFactor = 0)
     {
       if (m_allocatedSize<size)
-        reallocate(size + size_t(reserveSizeFactor*size));
+        reallocate(size + size_t(reserveSizeFactor*double(size)));
       m_size = size;
     }
 
diff --git a/Eigen/src/SparseCore/SparseMatrix.h b/Eigen/src/SparseCore/SparseMatrix.h
index e0b7494c1..ed935c40d 100644
--- a/Eigen/src/SparseCore/SparseMatrix.h
+++ b/Eigen/src/SparseCore/SparseMatrix.h
@@ -1178,7 +1178,7 @@ EIGEN_DONT_INLINE typename SparseMatrix<_Scalar,_Options,_Index>::Scalar& Sparse
   size_t p = m_outerIndex[outer+1];
   ++m_outerIndex[outer+1];
 
-  float reallocRatio = 1;
+  double reallocRatio = 1;
   if (m_data.allocatedSize()<=m_data.size())
   {
     // if there is no preallocated memory, let's reserve a minimum of 32 elements
@@ -1190,13 +1190,13 @@ EIGEN_DONT_INLINE typename SparseMatrix<_Scalar,_Options,_Index>::Scalar& Sparse
     {
       // we need to reallocate the data, to reduce multiple reallocations
       // we use a smart resize algorithm based on the current filling ratio
-      // in addition, we use float to avoid integers overflows
-      float nnzEstimate = float(m_outerIndex[outer])*float(m_outerSize)/float(outer+1);
-      reallocRatio = (nnzEstimate-float(m_data.size()))/float(m_data.size());
+      // in addition, we use double to avoid integers overflows
+      double nnzEstimate = double(m_outerIndex[outer])*double(m_outerSize)/double(outer+1);
+      reallocRatio = (nnzEstimate-double(m_data.size()))/double(m_data.size());
       // furthermore we bound the realloc ratio to:
       //   1) reduce multiple minor realloc when the matrix is almost filled
       //   2) avoid to allocate too much memory when the matrix is almost empty
-      reallocRatio = (std::min)((std::max)(reallocRatio,1.5f),8.f);
+      reallocRatio = (std::min)((std::max)(reallocRatio,1.5),8.);
     }
   }
   m_data.resize(m_data.size()+1,reallocRatio);