diff --git a/src/Invoice/Calculator/WeeklyInvoiceCalculator.php b/src/Invoice/Calculator/WeeklyInvoiceCalculator.php
new file mode 100644
index 00000000..5f50303b
--- /dev/null
+++ b/src/Invoice/Calculator/WeeklyInvoiceCalculator.php
@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Invoice\Calculator;
+
+use App\Invoice\CalculatorInterface;
+use App\Invoice\InvoiceItemInterface;
+
+/**
+ * A calculator that sums up the invoice item records per week.
+ */
+class WeeklyInvoiceCalculator extends AbstractSumInvoiceCalculator implements CalculatorInterface
+{
+    protected function calculateSumIdentifier(InvoiceItemInterface $invoiceItem): string
+    {
+        return $invoiceItem->getBegin()->format('W');
+    }
+
+    /**
+     * @return string
+     */
+    public function getId(): string
+    {
+        return 'weekly';
+    }
+}
diff --git a/src/Invoice/Hydrator/InvoiceItemDefaultHydrator.php b/src/Invoice/Hydrator/InvoiceItemDefaultHydrator.php
index 438ed95c..19c95d06 100644
--- a/src/Invoice/Hydrator/InvoiceItemDefaultHydrator.php
+++ b/src/Invoice/Hydrator/InvoiceItemDefaultHydrator.php
@@ -83,6 +83,8 @@ class InvoiceItemDefaultHydrator implements InvoiceItemHydrator
             'entry.end_time' => $formatter->getFormattedTime($end),
             'entry.end_timestamp' => $end->getTimestamp(),
             'entry.date' => $formatter->getFormattedDateTime($begin),
+            'entry.week' => \intval($begin->format('W')),
+            'entry.weekyear' => $begin->format('o'),
             'entry.user_id' => $user->getId(),
             'entry.user_name' => $user->getUsername(),
             'entry.user_title' => $user->getTitle(),
diff --git a/tests/Invoice/Calculator/WeeklyInvoiceCalculatorTest.php b/tests/Invoice/Calculator/WeeklyInvoiceCalculatorTest.php
new file mode 100644
index 00000000..bc5ddd66
--- /dev/null
+++ b/tests/Invoice/Calculator/WeeklyInvoiceCalculatorTest.php
@@ -0,0 +1,137 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Tests\Invoice\Calculator;
+
+use App\Entity\Activity;
+use App\Entity\Customer;
+use App\Entity\InvoiceTemplate;
+use App\Entity\Project;
+use App\Entity\Timesheet;
+use App\Entity\User;
+use App\Invoice\Calculator\WeeklyInvoiceCalculator;
+use App\Invoice\InvoiceModel;
+use App\Repository\Query\InvoiceQuery;
+use App\Tests\Invoice\DebugFormatter;
+use DateTime;
+
+/**
+ * @covers \App\Invoice\Calculator\WeeklyInvoiceCalculator
+ * @covers \App\Invoice\Calculator\AbstractSumInvoiceCalculator
+ * @covers \App\Invoice\Calculator\AbstractMergedCalculator
+ * @covers \App\Invoice\Calculator\AbstractCalculator
+ */
+class WeeklyInvoiceCalculatorTest extends AbstractCalculatorTest
+{
+    public function testEmptyModel()
+    {
+        $this->assertEmptyModel(new WeeklyInvoiceCalculator());
+    }
+
+    public function testWithMultipleEntries()
+    {
+        $customer = new Customer();
+        $template = new InvoiceTemplate();
+        $template->setVat(19);
+
+        $user = $this->getMockBuilder(User::class)->onlyMethods(['getId'])->disableOriginalConstructor()->getMock();
+        $user->method('getId')->willReturn(1);
+
+        $project1 = $this->getMockBuilder(Project::class)->onlyMethods(['getId'])->disableOriginalConstructor()->getMock();
+        $project1->method('getId')->willReturn(1);
+
+        $project2 = $this->getMockBuilder(Project::class)->onlyMethods(['getId'])->disableOriginalConstructor()->getMock();
+        $project2->method('getId')->willReturn(2);
+
+        $project3 = $this->getMockBuilder(Project::class)->onlyMethods(['getId'])->disableOriginalConstructor()->getMock();
+        $project3->method('getId')->willReturn(3);
+
+        $timesheet = new Timesheet();
+        $timesheet
+            ->setBegin(new DateTime('2018-11-29'))
+            ->setEnd(new DateTime())
+            ->setDuration(3600)
+            ->setRate(293.27)
+            ->setUser($user)
+            ->setActivity((new Activity())->setName('sdsd'))
+            ->setProject($project1);
+
+        $timesheet2 = new Timesheet();
+        $timesheet2
+            ->setBegin(new DateTime('2018-11-29'))
+            ->setEnd(new DateTime())
+            ->setDuration(400)
+            ->setRate(84.75)
+            ->setUser($user)
+            ->setActivity((new Activity())->setName('bar'))
+            ->setProject($project2);
+
+        $timesheet3 = new Timesheet();
+        $timesheet3
+            ->setBegin(new DateTime('2018-11-28'))
+            ->setEnd(new DateTime())
+            ->setDuration(1800)
+            ->setRate(111.11)
+            ->setUser($user)
+            ->setActivity((new Activity())->setName('foo'))
+            ->setProject($project1);
+
+        $timesheet4 = new Timesheet();
+        $timesheet4
+            ->setBegin(new DateTime())
+            ->setEnd(new DateTime('2018-11-28'))
+            ->setDuration(400)
+            ->setRate(1947.99)
+            ->setUser($user)
+            ->setActivity((new Activity())->setName('blub'))
+            ->setProject($project2);
+
+        $timesheet5 = new Timesheet();
+        $timesheet5
+            ->setBegin(new DateTime('2018-11-28'))
+            ->setEnd(new DateTime())
+            ->setDuration(400)
+            ->setRate(84)
+            ->setUser(new User())
+            ->setActivity(new Activity())
+            ->setProject($project3);
+
+        $entries = [$timesheet, $timesheet2, $timesheet3, $timesheet4, $timesheet5];
+
+        $query = new InvoiceQuery();
+        $query->setProjects([$project1]);
+
+        $model = new InvoiceModel(new DebugFormatter());
+        $model->setCustomer($customer);
+        $model->setTemplate($template);
+        $model->addEntries($entries);
+        $model->setQuery($query);
+
+        $sut = new WeeklyInvoiceCalculator();
+        $sut->setModel($model);
+
+        $this->assertEquals('weekly', $sut->getId());
+        $this->assertEquals(3000.13, $sut->getTotal());
+        $this->assertEquals(19, $sut->getVat());
+        $this->assertEquals('EUR', $model->getCurrency());
+        $this->assertEquals(2521.12, $sut->getSubtotal());
+        $this->assertEquals(6600, $sut->getTimeWorked());
+
+        $entries = $sut->getEntries();
+        self::assertCount(2, $entries);
+        $this->assertEquals(573.13, $entries[0]->getRate());
+        $this->assertEquals(1947.99, $entries[1]->getRate());
+        self::assertEquals(2521.12, $entries[0]->getRate() + $entries[1]->getRate());
+    }
+
+    public function testDescriptionByTimesheet()
+    {
+        $this->assertDescription(new WeeklyInvoiceCalculator(), false, false);
+    }
+}
diff --git a/tests/Invoice/Hydrator/InvoiceItemDefaultHydratorTest.php b/tests/Invoice/Hydrator/InvoiceItemDefaultHydratorTest.php
index 92254b94..396a51e6 100644
--- a/tests/Invoice/Hydrator/InvoiceItemDefaultHydratorTest.php
+++ b/tests/Invoice/Hydrator/InvoiceItemDefaultHydratorTest.php
@@ -62,6 +62,8 @@ class InvoiceItemDefaultHydratorTest extends TestCase
             'entry.end_time',
             'entry.end_timestamp',
             'entry.date',
+            'entry.week',
+            'entry.weekyear',
             'entry.user_id',
             'entry.user_name',
             'entry.user_alias',
diff --git a/tests/Invoice/Renderer/DebugRendererTest.php b/tests/Invoice/Renderer/DebugRendererTest.php
index d14a5cb9..f2934532 100644
--- a/tests/Invoice/Renderer/DebugRendererTest.php
+++ b/tests/Invoice/Renderer/DebugRendererTest.php
@@ -225,6 +225,8 @@ class DebugRendererTest extends TestCase
             'entry.end_time',
             'entry.end_timestamp',
             'entry.date',
+            'entry.week',
+            'entry.weekyear',
             'entry.user_id',
             'entry.user_name',
             'entry.user_alias',
diff --git a/translations/invoice-calculator.de.xlf b/translations/invoice-calculator.de.xlf
index 96feaaac..74755b2b 100644
--- a/translations/invoice-calculator.de.xlf
+++ b/translations/invoice-calculator.de.xlf
@@ -30,6 +30,10 @@
                 <source>date</source>
                 <target>Datum: ein Eintrag pro Tag (verwendet Startdatum)</target>
             </trans-unit>
+            <trans-unit id="weekly">
+                <source>weekly</source>
+                <target>Wöchentlich: ein Eintrag pro Woche (verwendet Startdatum)</target>
+            </trans-unit>
         </body>
     </file>
 </xliff>
diff --git a/translations/invoice-calculator.en.xlf b/translations/invoice-calculator.en.xlf
index 5dbc0986..f3427283 100644
--- a/translations/invoice-calculator.en.xlf
+++ b/translations/invoice-calculator.en.xlf
@@ -30,6 +30,10 @@
                 <source>date</source>
                 <target>Date: one entry per day (uses start date)</target>
             </trans-unit>
+            <trans-unit id="weekly">
+                <source>weekly</source>
+                <target>Weekly: one entry per week (uses start date)</target>
+            </trans-unit>
         </body>
     </file>
 </xliff>