diff --git a/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/PurchaseCalculator.java b/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/PurchaseCalculator.java
index 076032c..efac008 100644
--- a/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/PurchaseCalculator.java
+++ b/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/PurchaseCalculator.java
@@ -1,4 +1,34 @@
 package edu.ntnu.idi.idatt2003.gruppe42.Model.Calculator;
 
-public class PurchaseCalculator {
+import edu.ntnu.idi.idatt2003.gruppe42.Model.Share;
+import java.math.BigDecimal;
+
+public class PurchaseCalculator implements TransactionCalculator {
+  private BigDecimal purchasePrice;
+  private BigDecimal quantity;
+
+  public PurchaseCalculator(Share share) {
+    this.purchasePrice = share.getPurchasePrice();
+    this.quantity = share.getQuantity();
+  }
+
+  @Override
+  public BigDecimal calculateGross() {
+    return null;
+  }
+
+  @Override
+  public BigDecimal calculateCommission() {
+    return null;
+  }
+
+  @Override
+  public BigDecimal calculateTax() {
+    return null;
+  }
+
+  @Override
+  public BigDecimal calculateTotal() {
+    return null;
+  }
 }
diff --git a/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/SaleCalculator.java b/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/SaleCalculator.java
index bd7badb..833d5ae 100644
--- a/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/SaleCalculator.java
+++ b/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/SaleCalculator.java
@@ -1,4 +1,36 @@
 package edu.ntnu.idi.idatt2003.gruppe42.Model.Calculator;
 
-public class SaleCalculator {
+import edu.ntnu.idi.idatt2003.gruppe42.Model.Share;
+import java.math.BigDecimal;
+
+public class SaleCalculator implements TransactionCalculator {
+  private BigDecimal purchasePrice;
+  private BigDecimal salesPrice;
+  private BigDecimal quantity;
+
+  public SaleCalculator(Share share) {
+    this.purchasePrice = share.getPurchasePrice();
+    this.salesPrice = share.getStock().getSalesPrice();
+    this.quantity = share.getQuantity();
+  }
+
+  @Override
+  public BigDecimal calculateGross() {
+    return null;
+  }
+
+  @Override
+  public BigDecimal calculateCommission() {
+    return null;
+  }
+
+  @Override
+  public BigDecimal calculateTax() {
+    return null;
+  }
+
+  @Override
+  public BigDecimal calculateTotal() {
+    return null;
+  }
 }
diff --git a/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/TransactionCalculator.java b/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/TransactionCalculator.java
index 9e35b4e..361b224 100644
--- a/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/TransactionCalculator.java
+++ b/src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Calculator/TransactionCalculator.java
@@ -1,4 +1,14 @@
 package edu.ntnu.idi.idatt2003.gruppe42.Model.Calculator;
 
+import java.math.BigDecimal;
+
 public interface TransactionCalculator {
+
+  BigDecimal calculateGross();
+
+  BigDecimal calculateCommission();
+
+  BigDecimal calculateTax();
+
+  BigDecimal calculateTotal();
 }