diff --git a/src/KSPACE/ewald.cpp b/src/KSPACE/ewald.cpp
index 7a383d8472..04ebd7eb82 100644
--- a/src/KSPACE/ewald.cpp
+++ b/src/KSPACE/ewald.cpp
@@ -174,9 +174,9 @@ void Ewald::init()
   double lpry = rms(kymax,yprd,natoms,q2);
   double lprz = rms(kzmax,zprd_slab,natoms,q2);
   double lpr = sqrt(lprx*lprx + lpry*lpry + lprz*lprz) / sqrt(3.0);
-  double spr = 2.0*q2 * exp(-g_ewald*g_ewald*cutoff*cutoff) /
-    sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
-  double tpr = estimate_table_accuracy(spr);
+  double q2_over_sqrt = q2 / sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
+  double spr = 2.0 *q2_over_sqrt * exp(-g_ewald*g_ewald*cutoff*cutoff);
+  double tpr = estimate_table_accuracy(q2_over_sqrt,spr);
   double accuracy = sqrt(lpr*lpr + spr*spr + tpr*tpr);
 
   // stats
diff --git a/src/KSPACE/pppm.cpp b/src/KSPACE/pppm.cpp
index 966d3a98a8..a4aed0f3a7 100644
--- a/src/KSPACE/pppm.cpp
+++ b/src/KSPACE/pppm.cpp
@@ -1089,9 +1089,9 @@ void PPPM::set_grid()
   double lpry = rms(h_y,yprd,natoms,q2,acons);
   double lprz = rms(h_z,zprd_slab,natoms,q2,acons);
   double lpr = sqrt(lprx*lprx + lpry*lpry + lprz*lprz) / sqrt(3.0);
-  double spr = 2.0*q2 * exp(-g_ewald*g_ewald*cutoff*cutoff) /
-    sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
-  double tpr = estimate_table_accuracy(spr);
+  double q2_over_sqrt = q2 / sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
+  double spr = 2.0 *q2_over_sqrt * exp(-g_ewald*g_ewald*cutoff*cutoff);
+  double tpr = estimate_table_accuracy(q2_over_sqrt,spr);
   double accuracy = sqrt(lpr*lpr + spr*spr + tpr*tpr);
 
   // free local memory
diff --git a/src/kspace.cpp b/src/kspace.cpp
index 397c2067c7..61fa8e400d 100644
--- a/src/kspace.cpp
+++ b/src/kspace.cpp
@@ -129,30 +129,31 @@ void KSpace::ev_setup(int eflag, int vflag)
    estimate the accuracy of the short-range coulomb tables
 ------------------------------------------------------------------------- */
 
-double KSpace::estimate_table_accuracy(double spr)
+double KSpace::estimate_table_accuracy(double q2_over_sqrt, double spr)
 {
   double table_accuracy = 0.0;
   int nctb = force->pair->ncoultablebits;
   if (nctb) {
     double empirical_precision[17];
-    empirical_precision[6] = 2.12E-04;
-    empirical_precision[7] = 4.97E-05;
-    empirical_precision[8] = 1.24E-05;
-    empirical_precision[9] = 3.04E-06;
-    empirical_precision[10] = 8.51E-07;
-    empirical_precision[11] = 1.85E-07;
-    empirical_precision[12] = 5.87E-08;
-    empirical_precision[13] = 2.81E-08;
-    empirical_precision[14] = 2.20E-08;
-    empirical_precision[15] = 2.13E-08;
-    empirical_precision[16] = 2.11E-08;
+    empirical_precision[6] =  6.99E-03;
+    empirical_precision[7] =  1.78E-03;
+    empirical_precision[8] =  4.72E-04;
+    empirical_precision[9] =  1.17E-04;
+    empirical_precision[10] = 2.95E-05;
+    empirical_precision[11] = 7.41E-06;
+    empirical_precision[12] = 1.76E-06;
+    empirical_precision[13] = 9.28E-07;
+    empirical_precision[14] = 7.46E-07;
+    empirical_precision[15] = 7.32E-07;
+    empirical_precision[16] = 7.30E-07;
     if (nctb <= 6) table_accuracy = empirical_precision[6];
     else if (nctb <= 16) table_accuracy = empirical_precision[nctb];
     else table_accuracy = empirical_precision[16];
-    table_accuracy *= two_charge_force;
+    table_accuracy *= q2_over_sqrt;
     if (table_accuracy > spr)
       error->warning(FLERR,"For better accuracy use 'pair_modify table 0'");
   }
+
   return table_accuracy;
 }
 
diff --git a/src/kspace.h b/src/kspace.h
index eeb586a287..cfa3dafc9a 100644
--- a/src/kspace.h
+++ b/src/kspace.h
@@ -70,7 +70,7 @@ class KSpace : protected Pointers {
   int maxeatom,maxvatom;
 
   void ev_setup(int, int);
-  double estimate_table_accuracy(double);
+  double estimate_table_accuracy(double, double);
 };
 
 }