diff --git a/CMakeLists_files.cmake b/CMakeLists_files.cmake
index d01dddbf8..4a7bc041f 100644
--- a/CMakeLists_files.cmake
+++ b/CMakeLists_files.cmake
@@ -99,6 +99,7 @@ list (APPEND MAIN_SOURCE_FILES
   opm/simulators/wells/BlackoilWellModelGuideRates.cpp
   opm/simulators/wells/BlackoilWellModelRestart.cpp
   opm/simulators/wells/ConnFiltrateData.cpp
+  opm/simulators/wells/FractionCalculator.cpp
   opm/simulators/wells/GasLiftCommon.cpp
   opm/simulators/wells/GasLiftGroupInfo.cpp
   opm/simulators/wells/GasLiftSingleWellGeneric.cpp
@@ -568,6 +569,7 @@ list (APPEND PUBLIC_HEADER_FILES
   opm/simulators/wells/BlackoilWellModelGuideRates.hpp
   opm/simulators/wells/BlackoilWellModelRestart.hpp
   opm/simulators/wells/ConnFiltrateData.hpp
+  opm/simulators/wells/FractionCalculator.hpp
   opm/simulators/wells/GasLiftCommon.hpp
   opm/simulators/wells/GasLiftGroupInfo.hpp
   opm/simulators/wells/GasLiftSingleWellGeneric.hpp
diff --git a/opm/simulators/wells/FractionCalculator.cpp b/opm/simulators/wells/FractionCalculator.cpp
new file mode 100644
index 000000000..2a7a4f574
--- /dev/null
+++ b/opm/simulators/wells/FractionCalculator.cpp
@@ -0,0 +1,177 @@
+/*
+  Copyright 2019 Norce.
+  Copyright 2020 Equinor ASA.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <config.h>
+#include <opm/simulators/wells/FractionCalculator.hpp>
+
+#include <opm/input/eclipse/Schedule/Schedule.hpp>
+#include <opm/input/eclipse/Schedule/Well/Well.hpp>
+
+#include <opm/simulators/wells/GroupState.hpp>
+#include <opm/simulators/wells/WellGroupHelpers.hpp>
+#include <opm/simulators/wells/WellState.hpp>
+
+#include <cassert>
+
+namespace Opm::WellGroupHelpers {
+
+FractionCalculator::FractionCalculator(const Schedule& schedule,
+                                       const WellState& well_state,
+                                       const GroupState& group_state,
+                                       const int report_step,
+                                       const GuideRate* guide_rate,
+                                       const GuideRateModel::Target target,
+                                       const PhaseUsage& pu,
+                                       const bool is_producer,
+                                       const Phase injection_phase)
+    : schedule_(schedule)
+    , well_state_(well_state)
+    , group_state_(group_state)
+    , report_step_(report_step)
+    , guide_rate_(guide_rate)
+    , target_(target)
+    , pu_(pu)
+    , is_producer_(is_producer)
+    , injection_phase_(injection_phase)
+{
+}
+
+double FractionCalculator::fraction(const std::string& name,
+                                    const std::string& control_group_name,
+                                    const bool always_include_this)
+{
+    double fraction = 1.0;
+    std::string current = name;
+    while (current != control_group_name) {
+        fraction *= localFraction(current, always_include_this ? name : "");
+        current = parent(current);
+    }
+    return fraction;
+}
+
+double FractionCalculator::localFraction(const std::string& name,
+                                         const std::string& always_included_child)
+{
+    const double my_guide_rate = guideRate(name, always_included_child);
+    const Group& parent_group = schedule_.getGroup(parent(name), report_step_);
+    const double total_guide_rate = guideRateSum(parent_group, always_included_child);
+
+    // the total guide gate is the same as my_guide rate
+    // the well/group is probably on its own, i.e. return 1
+    // even is its guide_rate is zero
+    const double guide_rate_epsilon = 1e-12;
+    if ( std::abs(my_guide_rate - total_guide_rate) < guide_rate_epsilon )
+        return 1.0;
+
+    assert(total_guide_rate > my_guide_rate);
+    return my_guide_rate / total_guide_rate;
+}
+
+std::string FractionCalculator::parent(const std::string& name)
+{
+    if (schedule_.hasWell(name)) {
+        return schedule_.getWell(name, report_step_).groupName();
+    } else {
+        return schedule_.getGroup(name, report_step_).parent();
+    }
+}
+
+double FractionCalculator::guideRateSum(const Group& group,
+                                        const std::string& always_included_child)
+{
+    double total_guide_rate = 0.0;
+    for (const std::string& child_group : group.groups()) {
+        bool included = (child_group == always_included_child);
+        if (is_producer_) {
+            const auto ctrl = this->group_state_.production_control(child_group);
+            included |= (ctrl == Group::ProductionCMode::FLD) ||
+                        (ctrl == Group::ProductionCMode::NONE);
+        } else {
+            const auto ctrl = this->group_state_.injection_control(child_group,
+                                                                   this->injection_phase_);
+            included |= (ctrl == Group::InjectionCMode::FLD) ||
+                        (ctrl == Group::InjectionCMode::NONE);
+        }
+        if (included) {
+            total_guide_rate += guideRate(child_group, always_included_child);
+        }
+    }
+    for (const std::string& child_well : group.wells()) {
+        bool included = (child_well == always_included_child);
+        if (is_producer_) {
+            included |= well_state_.isProductionGrup(child_well);
+        } else {
+            included |= well_state_.isInjectionGrup(child_well);
+        }
+
+        if (included) {
+            total_guide_rate += guideRate(child_well, always_included_child);
+        }
+    }
+    return total_guide_rate;
+}
+
+double FractionCalculator::guideRate(const std::string& name, const std::string& always_included_child)
+{
+    if (schedule_.hasWell(name, report_step_)) {
+        return WellGroupHelpers::getGuideRate(name, schedule_, well_state_, group_state_,
+                                              report_step_, guide_rate_, target_, pu_);
+    } else {
+        if (groupControlledWells(name, always_included_child) > 0) {
+            if (is_producer_ && guide_rate_->has(name)) {
+                return guide_rate_->get(name, target_, getGroupRateVector(name));
+            } else if (!is_producer_ && guide_rate_->has(name, injection_phase_)) {
+                return guide_rate_->get(name, injection_phase_);
+            } else {
+                // We are a group, with default guide rate.
+                // Compute guide rate by accumulating our children's guide rates.
+                const Group& group = schedule_.getGroup(name, report_step_);
+                const double eff = group.getGroupEfficiencyFactor();
+                return eff * guideRateSum(group, always_included_child);
+            }
+        } else {
+            // No group-controlled subordinate wells.
+            return 0.0;
+        }
+    }
+}
+
+int FractionCalculator::groupControlledWells(const std::string& group_name,
+                                             const std::string& always_included_child)
+{
+    return WellGroupHelpers::groupControlledWells(schedule_,
+                                                  well_state_,
+                                                  this->group_state_,
+                                                  report_step_,
+                                                  group_name,
+                                                  always_included_child,
+                                                  is_producer_,
+                                                  injection_phase_);
+}
+
+GuideRate::RateVector FractionCalculator::getGroupRateVector(const std::string& group_name)
+{
+    assert(is_producer_);
+    return WellGroupHelpers::getProductionGroupRateVector(this->group_state_,
+                                                          this->pu_,
+                                                          group_name);
+}
+
+} // namespace Opm::WGHelpers
diff --git a/opm/simulators/wells/FractionCalculator.hpp b/opm/simulators/wells/FractionCalculator.hpp
new file mode 100644
index 000000000..9d83c9ced
--- /dev/null
+++ b/opm/simulators/wells/FractionCalculator.hpp
@@ -0,0 +1,77 @@
+/*
+  Copyright 2019 Norce.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#ifndef OPM_FRACTION_CALCULATOR_HEADER_INCLUDED
+#define OPM_FRACTION_CALCULATOR_HEADER_INCLUDED
+
+#include <opm/input/eclipse/Schedule/Group/GuideRate.hpp>
+
+#include <string>
+
+namespace Opm {
+class GroupState;
+struct PhaseUsage;
+class Schedule;
+class WellState;
+}
+
+namespace Opm::WellGroupHelpers {
+
+class FractionCalculator
+{
+public:
+    FractionCalculator(const Schedule& schedule,
+                       const WellState& well_state,
+                       const GroupState& group_state,
+                       const int report_step,
+                       const GuideRate* guide_rate,
+                       const GuideRateModel::Target target,
+                       const PhaseUsage& pu,
+                       const bool is_producer,
+                       const Phase injection_phase);
+    double fraction(const std::string& name,
+                    const std::string& control_group_name,
+                    const bool always_include_this);
+    double localFraction(const std::string& name,
+                         const std::string& always_included_child);
+
+private:
+    std::string parent(const std::string& name);
+    double guideRateSum(const Group& group,
+                        const std::string& always_included_child);
+    double guideRate(const std::string& name,
+                     const std::string& always_included_child);
+    int groupControlledWells(const std::string& group_name,
+                             const std::string& always_included_child);
+    GuideRate::RateVector getGroupRateVector(const std::string& group_name);
+    const Schedule& schedule_;
+    const WellState& well_state_;
+    const GroupState& group_state_;
+    int report_step_;
+    const GuideRate* guide_rate_;
+    GuideRateModel::Target target_;
+    const PhaseUsage& pu_;
+    bool is_producer_;
+    Phase injection_phase_;
+};
+
+} // namespace Opm::WellGroupHelpers
+
+#endif // OPM_FRACTION_CALCULATOR_HEADER_INCLUDED
diff --git a/opm/simulators/wells/WellGroupControls.cpp b/opm/simulators/wells/WellGroupControls.cpp
index dba8bc0e1..8856297f7 100644
--- a/opm/simulators/wells/WellGroupControls.cpp
+++ b/opm/simulators/wells/WellGroupControls.cpp
@@ -30,6 +30,7 @@
 
 #include <opm/material/densead/Evaluation.hpp>
 
+#include <opm/simulators/wells/FractionCalculator.hpp>
 #include <opm/simulators/wells/GroupState.hpp>
 #include <opm/simulators/wells/TargetCalculator.hpp>
 #include <opm/simulators/wells/WellGroupHelpers.hpp>
diff --git a/opm/simulators/wells/WellGroupHelpers.cpp b/opm/simulators/wells/WellGroupHelpers.cpp
index dd7435e24..5aeb65b5b 100644
--- a/opm/simulators/wells/WellGroupHelpers.cpp
+++ b/opm/simulators/wells/WellGroupHelpers.cpp
@@ -35,6 +35,7 @@
 #include <opm/simulators/utils/DeferredLoggingErrorHelpers.hpp>
 #include <opm/simulators/utils/ParallelCommunication.hpp>
 
+#include <opm/simulators/wells/FractionCalculator.hpp>
 #include <opm/simulators/wells/GroupState.hpp>
 #include <opm/simulators/wells/RegionAverageCalculator.hpp>
 #include <opm/simulators/wells/TargetCalculator.hpp>
@@ -1074,130 +1075,6 @@ namespace WellGroupHelpers
         return num_wells;
     }
 
-    FractionCalculator::FractionCalculator(const Schedule& schedule,
-                                           const WellState& well_state,
-                                           const GroupState& group_state,
-                                           const int report_step,
-                                           const GuideRate* guide_rate,
-                                           const GuideRateModel::Target target,
-                                           const PhaseUsage& pu,
-                                           const bool is_producer,
-                                           const Phase injection_phase)
-        : schedule_(schedule)
-        , well_state_(well_state)
-        , group_state_(group_state)
-        , report_step_(report_step)
-        , guide_rate_(guide_rate)
-        , target_(target)
-        , pu_(pu)
-        , is_producer_(is_producer)
-        , injection_phase_(injection_phase)
-    {
-    }
-    double FractionCalculator::fraction(const std::string& name,
-                                        const std::string& control_group_name,
-                                        const bool always_include_this)
-    {
-        double fraction = 1.0;
-        std::string current = name;
-        while (current != control_group_name) {
-            fraction *= localFraction(current, always_include_this ? name : "");
-            current = parent(current);
-        }
-        return fraction;
-    }
-    double FractionCalculator::localFraction(const std::string& name, const std::string& always_included_child)
-    {
-        const double my_guide_rate = guideRate(name, always_included_child);
-        const Group& parent_group = schedule_.getGroup(parent(name), report_step_);
-        const double total_guide_rate = guideRateSum(parent_group, always_included_child);
-
-        // the total guide gate is the same as my_guide rate
-        // the well/group is probably on its own, i.e. return 1
-        // even is its guide_rate is zero
-        const double guide_rate_epsilon = 1e-12;
-        if ( std::abs(my_guide_rate - total_guide_rate) < guide_rate_epsilon )
-            return 1.0;
-
-        assert(total_guide_rate > my_guide_rate);
-        return my_guide_rate / total_guide_rate;
-    }
-    std::string FractionCalculator::parent(const std::string& name)
-    {
-        if (schedule_.hasWell(name)) {
-            return schedule_.getWell(name, report_step_).groupName();
-        } else {
-            return schedule_.getGroup(name, report_step_).parent();
-        }
-    }
-    double FractionCalculator::guideRateSum(const Group& group, const std::string& always_included_child)
-    {
-        double total_guide_rate = 0.0;
-        for (const std::string& child_group : group.groups()) {
-            bool included = (child_group == always_included_child);
-            if (is_producer_) {
-                const auto ctrl = this->group_state_.production_control(child_group);
-                included = included || (ctrl == Group::ProductionCMode::FLD) || (ctrl == Group::ProductionCMode::NONE);
-            } else {
-                const auto ctrl = this->group_state_.injection_control(child_group, this->injection_phase_);
-                included = included || (ctrl == Group::InjectionCMode::FLD) || (ctrl == Group::InjectionCMode::NONE);
-            }
-            if (included) {
-                total_guide_rate += guideRate(child_group, always_included_child);
-            }
-        }
-        for (const std::string& child_well : group.wells()) {
-            bool included = (child_well == always_included_child);
-            if (is_producer_) {
-                included = included || well_state_.isProductionGrup(child_well);
-            } else {
-                included = included || well_state_.isInjectionGrup(child_well);
-            }
-
-            if (included) {
-                total_guide_rate += guideRate(child_well, always_included_child);
-            }
-        }
-        return total_guide_rate;
-    }
-    double FractionCalculator::guideRate(const std::string& name, const std::string& always_included_child)
-    {
-        if (schedule_.hasWell(name, report_step_)) {
-            return getGuideRate(name, schedule_, well_state_, group_state_,
-                                report_step_, guide_rate_, target_, pu_);
-        } else {
-            if (groupControlledWells(name, always_included_child) > 0) {
-                if (is_producer_ && guide_rate_->has(name)) {
-                    return guide_rate_->get(name, target_, getGroupRateVector(name));
-                } else if (!is_producer_ && guide_rate_->has(name, injection_phase_)) {
-                    return guide_rate_->get(name, injection_phase_);
-                } else {
-                    // We are a group, with default guide rate.
-                    // Compute guide rate by accumulating our children's guide rates.
-                    const Group& group = schedule_.getGroup(name, report_step_);
-                    const double eff = group.getGroupEfficiencyFactor();
-                    return eff * guideRateSum(group, always_included_child);
-                }
-            } else {
-                // No group-controlled subordinate wells.
-                return 0.0;
-            }
-        }
-    }
-    int FractionCalculator::groupControlledWells(const std::string& group_name,
-                                                 const std::string& always_included_child)
-    {
-        return ::Opm::WellGroupHelpers::groupControlledWells(
-                                                             schedule_, well_state_, this->group_state_, report_step_, group_name, always_included_child, is_producer_, injection_phase_);
-    }
-
-    GuideRate::RateVector FractionCalculator::getGroupRateVector(const std::string& group_name)
-    {
-        assert(is_producer_);
-        return getProductionGroupRateVector(this->group_state_, this->pu_, group_name);
-    }
-
-
     std::vector<std::string>
     groupChainTopBot(const std::string& bottom, const std::string& top, const Schedule& schedule, const int report_step)
     {
diff --git a/opm/simulators/wells/WellGroupHelpers.hpp b/opm/simulators/wells/WellGroupHelpers.hpp
index c48862db1..573dc00b7 100644
--- a/opm/simulators/wells/WellGroupHelpers.hpp
+++ b/opm/simulators/wells/WellGroupHelpers.hpp
@@ -235,39 +235,6 @@ namespace WellGroupHelpers
                              const Phase injection_phase);
 
 
-    class FractionCalculator
-    {
-    public:
-        FractionCalculator(const Schedule& schedule,
-                           const WellState& well_state,
-                           const GroupState& group_state,
-                           const int report_step,
-                           const GuideRate* guide_rate,
-                           const GuideRateModel::Target target,
-                           const PhaseUsage& pu,
-                           const bool is_producer,
-                           const Phase injection_phase);
-        double fraction(const std::string& name, const std::string& control_group_name, const bool always_include_this);
-        double localFraction(const std::string& name, const std::string& always_included_child);
-
-    private:
-        std::string parent(const std::string& name);
-        double guideRateSum(const Group& group, const std::string& always_included_child);
-        double guideRate(const std::string& name, const std::string& always_included_child);
-        int groupControlledWells(const std::string& group_name, const std::string& always_included_child);
-        GuideRate::RateVector getGroupRateVector(const std::string& group_name);
-        const Schedule& schedule_;
-        const WellState& well_state_;
-        const GroupState& group_state_;
-        int report_step_;
-        const GuideRate* guide_rate_;
-        GuideRateModel::Target target_;
-        const PhaseUsage& pu_;
-        bool is_producer_;
-        Phase injection_phase_;
-    };
-
-
     std::pair<bool, double> checkGroupConstraintsInj(const std::string& name,
                                                      const std::string& parent,
                                                      const Group& group,