diff --git a/src/DataTables/PartsDataTable.php b/src/DataTables/PartsDataTable.php
index 9e6e2415..8dc94ba0 100644
--- a/src/DataTables/PartsDataTable.php
+++ b/src/DataTables/PartsDataTable.php
@@ -178,7 +178,22 @@ final class PartsDataTable implements DataTableTypeInterface
                 $amount = $context->getAmountSum();
                 $expiredAmount = $context->getExpiredAmountSum();
 
-                $ret = htmlspecialchars($this->amountFormatter->format($amount, $context->getPartUnit()));
+                $ret = '';
+
+                if ($context->isAmountUnknown()) {
+                    //When all amounts are unknown, we show a question mark
+                    if ($amount === 0.0) {
+                        $ret .= sprintf('<b class="text-primary" title="%s">?</b>',
+                            $this->translator->trans('part_lots.instock_unknown'));
+                    } else { //Otherwise mark it with greater equal and the (known) amount
+                        $ret .= sprintf('<b class="text-primary" title="%s">≥</b>',
+                            $this->translator->trans('part_lots.instock_unknown')
+                        );
+                        $ret .= htmlspecialchars($this->amountFormatter->format($amount, $context->getPartUnit()));
+                    }
+                } else {
+                    $ret .= htmlspecialchars($this->amountFormatter->format($amount, $context->getPartUnit()));
+                }
 
                 //If we have expired lots, we show them in parentheses behind
                 if ($expiredAmount > 0) {
diff --git a/src/Entity/Parts/PartTraits/InstockTrait.php b/src/Entity/Parts/PartTraits/InstockTrait.php
index 29d04c89..8ab300b5 100644
--- a/src/Entity/Parts/PartTraits/InstockTrait.php
+++ b/src/Entity/Parts/PartTraits/InstockTrait.php
@@ -160,9 +160,25 @@ trait InstockTrait
         return $this->getAmountSum() < $this->getMinAmount();
     }
 
+    /**
+     * Returns true, if at least one of the part lots has an unknown amount.
+     * It is possible that other part lots have a known amount, then getAmountSum() will return sum of all known amounts.
+     * @return bool True if at least one part lot has an unknown amount.
+     */
+    public function isAmountUnknown(): bool
+    {
+        foreach ($this->getPartLots() as $lot) {
+            if ($lot->isInstockUnknown()) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Returns the summed amount of this part (over all part lots)
-     * Part Lots that have unknown value or are expired, are not used for this value.
+     * Part Lots that have unknown value or are expired, are not used for this value (counted as 0).
      *
      * @return float The amount of parts given in partUnit
      */
diff --git a/templates/parts/info/_main_infos.html.twig b/templates/parts/info/_main_infos.html.twig
index e8ecd95c..99c20126 100644
--- a/templates/parts/info/_main_infos.html.twig
+++ b/templates/parts/info/_main_infos.html.twig
@@ -41,8 +41,17 @@
             <span class="text-muted">{{ helper.structural_entity_link(part.category) }}</span>
         </h6>
         <h6><i class="fas fa-shapes fa-fw"></i>
-            <span class="{% if part.notEnoughInstock %}text-danger font-weight-bold{% else %}text-muted{% endif %}">
-                <span title="{% trans %}instock.label{% endtrans %}">{{ part.amountSum | format_amount(part.partUnit) }}</span>
+            <span class="{% if part.notEnoughInstock and not part.amountUnknown %}text-danger font-weight-bold{% else %}text-muted{% endif %}">
+                {% if not part.amountUnknown %}
+                    {# For known instock we can just show the label as normal #}
+                    <span title="{% trans %}instock.label{% endtrans %}">{{ part.amountSum | format_amount(part.partUnit) }}</span>
+                {% else %}
+                    {% if part.amountSum == 0.0 %}
+                        <b title="{% trans %}part_lots.instock_unknown{% endtrans %}">?</b>
+                    {% else %}
+                        <span title="{% trans %}part_lots.instock_unknown{% endtrans %}">≥{{ part.amountSum | format_amount(part.partUnit) }}</span>
+                    {% endif %}
+                {% endif %}
                 {% if part.expiredAmountSum > 0 %}
                     <span title="{% trans %}part_lots.is_expired{% endtrans %}" class="text-muted">(+{{ part.expiredAmountSum }})</span>
                 {% endif %}