diff --git a/tienda_ilusion/don_confiao/static/js/calculate_subtotal_line.js b/tienda_ilusion/don_confiao/static/js/calculate_subtotal_line.js
new file mode 100644
index 0000000..6f10690
--- /dev/null
+++ b/tienda_ilusion/don_confiao/static/js/calculate_subtotal_line.js
@@ -0,0 +1,50 @@
+const quantity_lineRegexSelector = `[id^="${idPrefix}"][id$="${quantitySuffix}"]`;
+const price_lineRegexSelector = `[id^="${idPrefix}"][id$="${priceSuffix}"]`;
+
+function insertSubtotalField() {
+  // Selecciona la fila de precio unitario para añadir la fila del subtotal después de ella
+  const unitPriceRow = document.querySelector('input[id="id_saleline_set-0-unit_price"]').closest('tr');
+
+  // Crear una nueva fila para el subtotal
+  const subtotalRow = document.createElement('tr');
+  subtotalRow.innerHTML = `
+         <th><label for="id_saleline_set-0-subtotal">Subtotal:</label></th>
+         <td><input type="number" name="saleline_set-0-subtotal" id="id_saleline_set-0-subtotal" readonly></td>
+     `;
+
+     // Insertar la fila del subtotal después de la fila del precio unitario
+     unitPriceRow.after(subtotalRow);
+ }
+
+function calculateSubtotal(id) {
+     const quantityElement = document.getElementById(`id_saleline_set-${id}-quantity`);
+     const unitPriceElement = document.getElementById(`id_saleline_set-${id}-unit_price`);
+     const subtotalElement = document.getElementById(`id_saleline_set-${id}-subtotal`);
+
+     const quantity = parseFloat(quantityElement.value) || 0;
+     const unitPrice = parseFloat(unitPriceElement.value) || 0;
+     const subtotal = quantity * unitPrice;
+
+     subtotalElement.value = subtotal.toFixed(2);
+ }
+
+ // Inserta el campo subtotal al cargar la página
+ window.addEventListener('load', () => {
+   insertSubtotalField();
+
+   complete_form.addEventListener('change', function(event){
+     const quantityInputs = document.querySelectorAll(quantity_lineRegexSelector);
+     const ids = Array.prototype.map.call(quantityInputs, function(input) {
+       return input.id.match(/\d+/)[0];
+     });
+
+     ids.forEach(function(id) {
+       if (event.target.matches(quantity_lineRegexSelector)) {
+         calculateSubtotal(id);
+       }
+       if (event.target.matches(price_lineRegexSelector)) {
+         calculateSubtotal(id);
+       }
+     })
+   });
+ });
diff --git a/tienda_ilusion/don_confiao/templates/don_confiao/purchase.html b/tienda_ilusion/don_confiao/templates/don_confiao/purchase.html
index 2095a43..c21690b 100644
--- a/tienda_ilusion/don_confiao/templates/don_confiao/purchase.html
+++ b/tienda_ilusion/don_confiao/templates/don_confiao/purchase.html
@@ -18,4 +18,5 @@
   <br/><button name="form" type="submit" >Comprar</button>
   <script src="{% static 'js/add_line.js' %}"></script>
   <script src="{% static 'js/sale_summary.js' %}"></script>
+  <script src="{% static 'js/calculate_subtotal_line.js' %}"></script>
 </form>