diff --git a/src/Command/UpdateExchangeRatesCommand.php b/src/Command/UpdateExchangeRatesCommand.php
index 9e06669a..9f52e124 100644
--- a/src/Command/UpdateExchangeRatesCommand.php
+++ b/src/Command/UpdateExchangeRatesCommand.php
@@ -43,6 +43,7 @@ declare(strict_types=1);
 namespace App\Command;
 
 use App\Entity\PriceInformations\Currency;
+use Brick\Math\BigDecimal;
 use function count;
 use Doctrine\ORM\EntityManagerInterface;
 use Exchanger\Exception\Exception;
@@ -122,10 +123,11 @@ class UpdateExchangeRatesCommand extends Command
 
         //Iterate over each candidate and update exchange rate
         foreach ($candidates as $currency) {
+            /** @var Currency $currency */
             try {
                 $rate = $swap->latest($currency->getIsoCode().'/'.$this->base_current);
-                $currency->setExchangeRate((string) $rate->getValue());
-                $io->note(sprintf('Set exchange rate of %s to %f', $currency->getIsoCode(), $currency->getExchangeRate()));
+                $currency->setExchangeRate(BigDecimal::of($rate->getValue()));
+                $io->note(sprintf('Set exchange rate of %s to %f', $currency->getIsoCode(), $currency->getExchangeRate()->toFloat()));
                 $this->em->persist($currency);
 
                 ++$success_counter;
diff --git a/src/Entity/Parts/Supplier.php b/src/Entity/Parts/Supplier.php
index 7bf16083..e731c940 100644
--- a/src/Entity/Parts/Supplier.php
+++ b/src/Entity/Parts/Supplier.php
@@ -153,7 +153,7 @@ class Supplier extends AbstractCompany
     /**
      * Sets the shipping costs for an order with this supplier.
      *
-     * @param string|null $shipping_costs a BigDecimal with the shipping costs
+     * @param BigDecimal|null $shipping_costs a BigDecimal with the shipping costs
      *
      * @return Supplier
      */
diff --git a/src/Entity/PriceInformations/Currency.php b/src/Entity/PriceInformations/Currency.php
index 300bf0e0..90aa8f25 100644
--- a/src/Entity/PriceInformations/Currency.php
+++ b/src/Entity/PriceInformations/Currency.php
@@ -45,6 +45,9 @@ namespace App\Entity\PriceInformations;
 use App\Entity\Attachments\CurrencyAttachment;
 use App\Entity\Base\AbstractStructuralDBElement;
 use App\Entity\Parameters\CurrencyParameter;
+use App\Validator\Constraints\BigDecimal\BigDecimalPositive;
+use Brick\Math\BigDecimal;
+use Brick\Math\RoundingMode;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
 use Doctrine\ORM\Mapping as ORM;
@@ -63,10 +66,10 @@ class Currency extends AbstractStructuralDBElement
     public const PRICE_SCALE = 5;
 
     /**
-     * @var string|null The exchange rate between this currency and the base currency
+     * @var BigDecimal|null The exchange rate between this currency and the base currency
      *                  (how many base units the current currency is worth)
-     * @ORM\Column(type="decimal", precision=11, scale=5, nullable=true)
-     * @Assert\Positive()
+     * @ORM\Column(type="big_decimal", precision=11, scale=5, nullable=true)
+     * @BigDecimalPositive()
      */
     protected $exchange_rate;
 
@@ -148,22 +151,22 @@ class Currency extends AbstractStructuralDBElement
     /**
      * Returns the inverse exchange rate (how many of the current currency the base unit is worth).
      */
-    public function getInverseExchangeRate(): ?string
+    public function getInverseExchangeRate(): ?BigDecimal
     {
         $tmp = $this->getExchangeRate();
 
-        if (null === $tmp || '0' === $tmp) {
+        if (null === $tmp || $tmp->isZero()) {
             return null;
         }
 
-        return bcdiv('1', $tmp, static::PRICE_SCALE);
+        return BigDecimal::one()->dividedBy($tmp, $tmp->getScale(), RoundingMode::HALF_UP);
     }
 
     /**
      * Returns The exchange rate between this currency and the base currency
      * (how many base units the current currency is worth).
      */
-    public function getExchangeRate(): ?string
+    public function getExchangeRate(): ?BigDecimal
     {
         return $this->exchange_rate;
     }
@@ -171,12 +174,12 @@ class Currency extends AbstractStructuralDBElement
     /**
      * Sets the exchange rate of the currency.
      *
-     * @param string|null $exchange_rate The new exchange rate of the currency.
+     * @param BigDecimal|null $exchange_rate The new exchange rate of the currency.
      *                                   Set to null, if the exchange rate is unknown.
      *
      * @return Currency
      */
-    public function setExchangeRate(?string $exchange_rate): self
+    public function setExchangeRate(?BigDecimal $exchange_rate): self
     {
         $this->exchange_rate = $exchange_rate;
 
diff --git a/src/Form/AdminPages/CurrencyAdminForm.php b/src/Form/AdminPages/CurrencyAdminForm.php
index 6f3e5a3c..cb53ca90 100644
--- a/src/Form/AdminPages/CurrencyAdminForm.php
+++ b/src/Form/AdminPages/CurrencyAdminForm.php
@@ -43,6 +43,7 @@ declare(strict_types=1);
 namespace App\Form\AdminPages;
 
 use App\Entity\Base\AbstractNamedDBElement;
+use App\Form\Type\BigDecimalMoneyType;
 use Symfony\Component\Form\Extension\Core\Type\CurrencyType;
 use Symfony\Component\Form\Extension\Core\Type\MoneyType;
 use Symfony\Component\Form\FormBuilderInterface;
@@ -74,7 +75,7 @@ class CurrencyAdminForm extends BaseEntityAdminForm
             'disabled' => ! $this->security->isGranted($is_new ? 'create' : 'edit', $entity),
         ]);
 
-        $builder->add('exchange_rate', MoneyType::class, [
+        $builder->add('exchange_rate', BigDecimalMoneyType::class, [
             'required' => false,
             'label' => 'currency.edit.exchange_rate',
             'currency' => $this->default_currency,
diff --git a/src/Services/PricedetailHelper.php b/src/Services/PricedetailHelper.php
index ac480c14..0da8eb31 100644
--- a/src/Services/PricedetailHelper.php
+++ b/src/Services/PricedetailHelper.php
@@ -213,11 +213,11 @@ class PricedetailHelper
         $val_base = $value;
         if (null !== $originCurrency) {
             //Without an exchange rate we can not calculate the exchange rate
-            if (0.0 === (float) $originCurrency->getExchangeRate()) {
+            if ($originCurrency->getExchangeRate() === null || $originCurrency->getExchangeRate()->isZero()) {
                 return null;
             }
 
-            $val_base = bcmul($value, $originCurrency->getExchangeRate(), Pricedetail::PRICE_PRECISION);
+            $val_base = bcmul($value, (string) $originCurrency->getExchangeRate(), Pricedetail::PRICE_PRECISION);
         }
 
         //Convert value in base currency to target currency
@@ -228,7 +228,7 @@ class PricedetailHelper
                 return null;
             }
 
-            $val_target = bcmul($val_base, $targetCurrency->getInverseExchangeRate(), Pricedetail::PRICE_PRECISION);
+            $val_target = bcmul($val_base, (string) $targetCurrency->getInverseExchangeRate(), Pricedetail::PRICE_PRECISION);
         }
 
         return $val_target;
diff --git a/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThanValidator.php b/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThanValidator.php
new file mode 100644
index 00000000..e140223c
--- /dev/null
+++ b/src/Validator/Constraints/BigDecimal/BigDecimalGreaterThanValidator.php
@@ -0,0 +1,59 @@
+<?php
+/**
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ * Copyright (C) 2019 - 2020 Jan Böhmer (https://github.com/jbtronics)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace App\Validator\Constraints\BigDecimal;
+
+
+use Brick\Math\BigDecimal;
+use Symfony\Component\Validator\Constraints\AbstractComparisonValidator;
+use Symfony\Component\Validator\Constraints\GreaterThan;
+
+/**
+ * Validates values are greater than the previous (>).
+ *
+ * @author Daniel Holmes <daniel@danielholmes.org>
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class BigDecimalGreaterThanValidator extends AbstractComparisonValidator
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function compareValues($value1, $value2)
+    {
+        if ($value1 instanceof BigDecimal) {
+            $value1 = (string) $value1;
+        }
+
+        if ($value2 instanceof BigDecimal) {
+            $value2 = (string) $value2;
+        }
+
+        return null === $value2 || $value1 > $value2;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function getErrorCode()
+    {
+        return GreaterThan::TOO_LOW_ERROR;
+    }
+}
\ No newline at end of file
diff --git a/src/Validator/Constraints/BigDecimal/BigDecimalPositive.php b/src/Validator/Constraints/BigDecimal/BigDecimalPositive.php
new file mode 100644
index 00000000..aa92a3ab
--- /dev/null
+++ b/src/Validator/Constraints/BigDecimal/BigDecimalPositive.php
@@ -0,0 +1,49 @@
+<?php
+/**
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ * Copyright (C) 2019 - 2020 Jan Böhmer (https://github.com/jbtronics)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace App\Validator\Constraints\BigDecimal;
+
+
+use Symfony\Component\Validator\Constraints\GreaterThan;
+use Symfony\Component\Validator\Constraints\GreaterThanValidator;
+use Symfony\Component\Validator\Constraints\NumberConstraintTrait;
+
+/**
+ * @Annotation
+ * @Target({"PROPERTY", "METHOD", "ANNOTATION"})
+ *
+ * @author Jan Schädlich <jan.schaedlich@sensiolabs.de>
+ */
+class BigDecimalPositive extends GreaterThan
+{
+    use NumberConstraintTrait;
+
+    public $message = 'This value should be positive.';
+
+    public function __construct($options = null)
+    {
+        parent::__construct($this->configureNumberConstraintOptions($options));
+    }
+
+    public function validatedBy(): string
+    {
+        return BigDecimalGreaterThanValidator::class;
+    }
+}
\ No newline at end of file
diff --git a/templates/AdminPages/CurrencyAdmin.html.twig b/templates/AdminPages/CurrencyAdmin.html.twig
index ed50f108..43f443d3 100644
--- a/templates/AdminPages/CurrencyAdmin.html.twig
+++ b/templates/AdminPages/CurrencyAdmin.html.twig
@@ -20,7 +20,7 @@
     {{ form_row(form.exchange_rate) }}
     {% if entity.inverseExchangeRate %}
         <span class="form-text text-muted offset-3 col-9">
-        {{ '1'|format_currency(default_currency) }} = {{ entity.inverseExchangeRate | format_currency(entity.isoCode, {fraction_digit: 5}) }}
+        {{ '1'|format_currency(default_currency) }} = {{ entity.inverseExchangeRate.tofloat | format_currency(entity.isoCode, {fraction_digit: 5}) }}
     </span>
     {% endif %}
 {% endblock %}
diff --git a/tests/Entity/PriceSystem/CurrencyTest.php b/tests/Entity/PriceSystem/CurrencyTest.php
index 810f51ac..07a7e030 100644
--- a/tests/Entity/PriceSystem/CurrencyTest.php
+++ b/tests/Entity/PriceSystem/CurrencyTest.php
@@ -43,6 +43,7 @@ declare(strict_types=1);
 namespace App\Tests\Entity\PriceSystem;
 
 use App\Entity\PriceInformations\Currency;
+use Brick\Math\BigDecimal;
 use PHPUnit\Framework\TestCase;
 
 class CurrencyTest extends TestCase
@@ -54,10 +55,10 @@ class CurrencyTest extends TestCase
         //By default the inverse exchange rate is not set:
         $this->assertNull($currency->getInverseExchangeRate());
 
-        $currency->setExchangeRate('0');
+        $currency->setExchangeRate(BigDecimal::zero());
         $this->assertNull($currency->getInverseExchangeRate());
 
-        $currency->setExchangeRate('1.45643');
-        $this->assertSame('0.68661', $currency->getInverseExchangeRate());
+        $currency->setExchangeRate(BigDecimal::of('1.45643'));
+        $this->assertSame(BigDecimal::of('0.68661'), $currency->getInverseExchangeRate());
     }
 }