diff --git a/financeplanner/calc.py b/financeplanner/calc.py
new file mode 100644
index 0000000..ac2e85e
--- /dev/null
+++ b/financeplanner/calc.py
@@ -0,0 +1,80 @@
+from dateutil.relativedelta import relativedelta
+from django.db.models import Q
+
+from financeplanner.utils import current_date
+
+
+class ActualTransaction:
+
+    def __init__(self, date, subject, amount):
+        self.date = date
+        self.subject = subject
+        self.amount = amount
+
+
+class Statistics:
+
+    def __init__(self, user):
+        self.user = user
+        self.today = current_date()
+        self.start = self.today - relativedelta(months=6)
+        self.end = self.today + relativedelta(months=6)
+        self.calc_start = self.start
+        self.balances = []
+        self.transactions = []
+        self.actual_transactions = []
+
+    def _fetch_relevant_balances(self):
+        balances = []
+        balances_until_start = self.user.balances.filter(date__lte=self.start)
+        if balances_until_start.exists():
+            balances = [balances_until_start.latest("date")]
+        other_balances = self.user.balances.filter(date__gt=self.start, date__lte=self.end).order_by("date")
+        self.balances = balances + list(other_balances)
+        if self.balances:
+            self.calc_start = self.balances[0].date
+
+    def _fetch_relevant_transactions(self):
+        one_time_in_range = Q(
+            booking_date__gte=self.calc_start,
+            booking_date__lte=self.end,
+            recurring_months__isnull=True,
+        )
+        endlessly_recurring = Q(
+            booking_date__lte=self.end,
+            recurring_months__isnull=False,
+            not_recurring_after__isnull=True,
+        )
+        recurring_and_ending_in_range = Q(
+            booking_date__lte=self.end,
+            recurring_months__isnull=False,
+            not_recurring_after__gte=self.calc_start,
+        )
+        transactions = self.user.transactions.filter(
+            one_time_in_range | endlessly_recurring | recurring_and_ending_in_range
+        ).order_by("booking_date")
+        self.transactions = list(transactions)
+
+    def _calculate_actual_transactions(self):
+        actual_transaction = []
+        for trans in self.transactions:
+            if trans.recurring_months:
+                iter_date = trans.booking_date
+                iter_step = 1
+                limit = min(trans.not_recurring_after, self.end) if trans.not_recurring_after else self.end
+                while iter_date < limit:
+                    if iter_date >= self.calc_start:
+                        actual_transaction.append(ActualTransaction(
+                            date=iter_date,
+                            subject=f"{trans.subject} #{iter_step}",
+                            amount=trans.amount,
+                        ))
+                    iter_date += relativedelta(months=trans.recurring_months)
+                    iter_step += 1
+            else:
+                actual_transaction.append(ActualTransaction(
+                    date=trans.booking_date,
+                    subject=trans.subject,
+                    amount=trans.amount,
+                ))
+        self.actual_transactions = actual_transaction