diff --git a/app/Http/Requests/App/InventoryStoreRequest.php b/app/Http/Requests/App/InventoryStoreRequest.php
index e58aed7..7b1a88a 100644
--- a/app/Http/Requests/App/InventoryStoreRequest.php
+++ b/app/Http/Requests/App/InventoryStoreRequest.php
@@ -24,6 +24,7 @@ public function rules(): array
             'sku' => ['nullable', 'string', 'max:50', 'unique:inventories,sku'],
             'barcode' => ['nullable', 'string', 'unique:inventories,barcode'],
             'category_id' => ['required', 'exists:categories,id'],
+            'unit_of_measure_id' => ['required', 'exists:units_of_measurement,id'],
             'track_serials' => ['nullable', 'boolean'],
 
             // Campos de Price
@@ -60,6 +61,7 @@ public function messages(): array
 
     /**
      * Validación condicional: retail_price > cost solo si cost > 0
+     * Y validación track_serials con unidades decimales
      */
     public function withValidator($validator)
     {
@@ -73,6 +75,17 @@ public function withValidator($validator)
                     'El precio de venta debe ser mayor que el costo.'
                 );
             }
+
+            // Validar incompatibilidad track_serials + unidades decimales
+            if ($this->input('track_serials')) {
+                $unit = \App\Models\UnitOfMeasurement::find($this->input('unit_of_measure_id'));
+                if ($unit && $unit->allows_decimals) {
+                    $validator->errors()->add(
+                        'track_serials',
+                        'No se pueden usar seriales con unidades fraccionarias (kg, L, m). Cambia a Unidad/Pieza/Caja o desactiva los seriales.'
+                    );
+                }
+            }
         });
     }
 }
diff --git a/app/Http/Requests/App/InventoryUpdateRequest.php b/app/Http/Requests/App/InventoryUpdateRequest.php
index c47cf0c..2168aa3 100644
--- a/app/Http/Requests/App/InventoryUpdateRequest.php
+++ b/app/Http/Requests/App/InventoryUpdateRequest.php
@@ -26,6 +26,7 @@ public function rules(): array
             'sku' => ['nullable', 'string', 'max:50'],
             'barcode' => ['nullable', 'string', 'unique:inventories,barcode,' . $inventoryId],
             'category_id' => ['nullable', 'exists:categories,id'],
+            'unit_of_measure_id' => ['nullable', 'exists:units_of_measurement,id'],
             'track_serials' => ['nullable', 'boolean'],
 
             // Campos de Price
@@ -61,6 +62,7 @@ public function messages(): array
 
     /**
      * Validación condicional: retail_price > cost solo si cost > 0
+     * Y validación track_serials con unidades decimales
      */
     public function withValidator($validator)
     {
@@ -74,6 +76,20 @@ public function withValidator($validator)
                     'El precio de venta debe ser mayor que el costo.'
                 );
             }
+
+            // Validar incompatibilidad track_serials + unidades decimales
+            $trackSerials = $this->input('track_serials', $this->route('inventario')?->track_serials);
+            $unitId = $this->input('unit_of_measure_id', $this->route('inventario')?->unit_of_measure_id);
+
+            if ($trackSerials && $unitId) {
+                $unit = \App\Models\UnitOfMeasurement::find($unitId);
+                if ($unit && $unit->allows_decimals) {
+                    $validator->errors()->add(
+                        'track_serials',
+                        'No se pueden usar seriales con unidades fraccionarias (kg, L, m). Cambia a Unidad/Pieza/Caja o desactiva los seriales.'
+                    );
+                }
+            }
         });
     }
 }
diff --git a/app/Models/Inventory.php b/app/Models/Inventory.php
index 29226d7..a59513b 100644
--- a/app/Models/Inventory.php
+++ b/app/Models/Inventory.php
@@ -20,6 +20,7 @@ class Inventory extends Model
 {
     protected $fillable = [
         'category_id',
+        'unit_of_measure_id',
         'name',
         'sku',
         'barcode',
@@ -42,29 +43,29 @@ public function warehouses()
     }
 
     /**
-     * Stock total en todos los almacenes
+     * Stock total en todos los almacenes (ahora soporta decimales)
      */
-    public function getStockAttribute(): int
+    public function getStockAttribute(): float
     {
-        return $this->warehouses()->sum('inventory_warehouse.stock');
+        return (float) $this->warehouses()->sum('inventory_warehouse.stock');
     }
 
     /**
      * Alias para compatibilidad
      */
-    public function getTotalStockAttribute(): int
+    public function getTotalStockAttribute(): float
     {
         return $this->stock;
     }
 
     /**
-     * Stock en un almacén específico
+     * Stock en un almacén específico (ahora soporta decimales)
      */
-    public function stockInWarehouse(int $warehouseId): int
+    public function stockInWarehouse(int $warehouseId): float
     {
-        return $this->warehouses()
+        return (float) ($this->warehouses()
             ->where('warehouse_id', $warehouseId)
-            ->value('inventory_warehouse.stock') ?? 0;
+            ->value('inventory_warehouse.stock') ?? 0);
     }
 
     public function category()
@@ -72,6 +73,11 @@ public function category()
         return $this->belongsTo(Category::class);
     }
 
+    public function unitOfMeasure()
+    {
+        return $this->belongsTo(UnitOfMeasurement::class);
+    }
+
     public function price()
     {
         return $this->hasOne(Price::class);
diff --git a/app/Models/InventoryMovement.php b/app/Models/InventoryMovement.php
index d62dad3..05be84d 100644
--- a/app/Models/InventoryMovement.php
+++ b/app/Models/InventoryMovement.php
@@ -21,7 +21,7 @@ class InventoryMovement extends Model
     ];
 
     protected $casts = [
-        'quantity' => 'integer',
+        'quantity' => 'decimal:3',
         'unit_cost' => 'decimal:2',
         'created_at' => 'datetime',
     ];
diff --git a/app/Models/InventoryWarehouse.php b/app/Models/InventoryWarehouse.php
index a0ca484..dee1aa4 100644
--- a/app/Models/InventoryWarehouse.php
+++ b/app/Models/InventoryWarehouse.php
@@ -15,9 +15,9 @@ class InventoryWarehouse extends Model
     ];
 
     protected $casts = [
-        'stock' => 'integer',
-        'min_stock' => 'integer',
-        'max_stock' => 'integer',
+        'stock' => 'decimal:3',
+        'min_stock' => 'decimal:3',
+        'max_stock' => 'decimal:3',
     ];
 
     // Relaciones
@@ -38,7 +38,7 @@ public function isOverStock(): bool {
         return $this->max_stock && $this->stock >= $this->max_stock;
     }
 
-    public function hasAvailableStock(int $quantity): bool {
+    public function hasAvailableStock(float $quantity): bool {
         return $this->stock >= $quantity;
     }
 }
diff --git a/app/Models/ReturnDetail.php b/app/Models/ReturnDetail.php
index 61f01bc..72e4e32 100644
--- a/app/Models/ReturnDetail.php
+++ b/app/Models/ReturnDetail.php
@@ -15,9 +15,9 @@ class ReturnDetail extends Model
     ];
 
     protected $casts = [
+        'quantity_returned' => 'decimal:3',
         'unit_price' => 'decimal:2',
         'subtotal' => 'decimal:2',
-        'quantity_returned' => 'integer',
     ];
 
     /**
diff --git a/app/Models/SaleDetail.php b/app/Models/SaleDetail.php
index 2cbcb94..07b6821 100644
--- a/app/Models/SaleDetail.php
+++ b/app/Models/SaleDetail.php
@@ -28,6 +28,7 @@ class SaleDetail extends Model
     ];
 
     protected $casts = [
+        'quantity' => 'decimal:3',
         'unit_price' => 'decimal:2',
         'subtotal' => 'decimal:2',
         'discount_percentage' => 'decimal:2',
diff --git a/app/Models/UnitOfMeasurement.php b/app/Models/UnitOfMeasurement.php
new file mode 100644
index 0000000..2690a73
--- /dev/null
+++ b/app/Models/UnitOfMeasurement.php
@@ -0,0 +1,50 @@
+<?php namespace App\Models;
+/**
+ * @copyright (c) 2025 Notsoweb Software (https://notsoweb.com) - All Rights Reserved
+ */
+
+
+use Illuminate\Database\Eloquent\Model;
+
+/**
+ * Unidad de Medida
+ *
+ * Define las unidades de medida disponibles para los productos
+ * (Unidad, Kilogramo, Litro, Metro, etc.)
+ *
+ * @author Moisés Cortés C. <moises.cortes@notsoweb.com>
+ *
+ * @version 1.0.0
+ */
+class UnitOfMeasurement extends Model
+{
+    protected $table = 'units_of_measurement';
+
+    protected $fillable = [
+        'name',
+        'abbreviation',
+        'allows_decimals',
+        'is_active',
+    ];
+
+    protected $casts = [
+        'allows_decimals' => 'boolean',
+        'is_active' => 'boolean',
+    ];
+
+    /**
+     * Scope para unidades activas
+     */
+    public function scopeActive($query)
+    {
+        return $query->where('is_active', true);
+    }
+
+    /**
+     * Relación con inventarios
+     */
+    public function inventories()
+    {
+        return $this->hasMany(Inventory::class, 'unit_of_measure_id');
+    }
+}
diff --git a/database/migrations/2026_02_09_155850_create_units_of_measurement_table.php b/database/migrations/2026_02_09_155850_create_units_of_measurement_table.php
new file mode 100644
index 0000000..09c115c
--- /dev/null
+++ b/database/migrations/2026_02_09_155850_create_units_of_measurement_table.php
@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Support\Facades\DB;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('units_of_measurement', function (Blueprint $table) {
+            $table->id();
+            $table->string('name')->unique();
+            $table->string('abbreviation', 10);
+            $table->boolean('allows_decimals')->default(false);
+            $table->boolean('is_active')->default(true);
+            $table->timestamps();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('units_of_measurement');
+    }
+};
diff --git a/database/migrations/2026_02_09_155942_alter_quantities_to_decimal.php b/database/migrations/2026_02_09_155942_alter_quantities_to_decimal.php
new file mode 100644
index 0000000..70b7053
--- /dev/null
+++ b/database/migrations/2026_02_09_155942_alter_quantities_to_decimal.php
@@ -0,0 +1,61 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        // 1. inventory_warehouse.stock
+        Schema::table('inventory_warehouse', function (Blueprint $table) {
+            $table->decimal('stock', 15, 3)->default(0)->change();
+            $table->decimal('min_stock', 15, 3)->default(0)->change();
+            $table->decimal('max_stock', 15, 3)->default(0)->change();
+        });
+
+        // 2. sale_details.quantity
+        Schema::table('sale_details', function (Blueprint $table) {
+            $table->decimal('quantity', 15, 3)->change();
+        });
+
+        // 3. inventory_movements.quantity
+        Schema::table('inventory_movements', function (Blueprint $table) {
+            $table->decimal('quantity', 15, 3)->change();
+        });
+
+        // 4. return_details.quantity_returned
+        Schema::table('return_details', function (Blueprint $table) {
+            $table->decimal('quantity_returned', 15, 3)->change();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        // Revertir a integer
+        Schema::table('inventory_warehouse', function (Blueprint $table) {
+            $table->integer('stock')->default(0)->change();
+            $table->integer('min_stock')->default(0)->change();
+            $table->integer('max_stock')->default(0)->change();
+        });
+
+        Schema::table('sale_details', function (Blueprint $table) {
+            $table->integer('quantity')->change();
+        });
+
+        Schema::table('inventory_movements', function (Blueprint $table) {
+            $table->integer('quantity')->change();
+        });
+
+        Schema::table('return_details', function (Blueprint $table) {
+            $table->integer('quantity_returned')->change();
+        });
+    }
+};
diff --git a/database/migrations/2026_02_09_160008_add_unit_of_measure_id_to_inventories.php b/database/migrations/2026_02_09_160008_add_unit_of_measure_id_to_inventories.php
new file mode 100644
index 0000000..94986bf
--- /dev/null
+++ b/database/migrations/2026_02_09_160008_add_unit_of_measure_id_to_inventories.php
@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('inventories', function (Blueprint $table) {
+            $table->foreignId('unit_of_measure_id')
+                ->after('category_id')
+                ->constrained('units_of_measurement')
+                ->onDelete('restrict');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('inventories', function (Blueprint $table) {
+            $table->dropForeign(['unit_of_measure_id']);
+            $table->dropColumn('unit_of_measure_id');
+        });
+    }
+};
diff --git a/database/seeders/DevSeeder.php b/database/seeders/DevSeeder.php
index ffea706..d0e969f 100644
--- a/database/seeders/DevSeeder.php
+++ b/database/seeders/DevSeeder.php
@@ -7,9 +7,9 @@
 
 /**
  * Seeder de desarrollo
- * 
+ *
  * @author Moisés Cortés C. <moises.cortes@notsoweb.com>
- * 
+ *
  * @version 1.0.0
  */
 class DevSeeder extends Seeder
@@ -22,5 +22,7 @@ public function run(): void
         $this->call(RoleSeeder::class);
         $this->call(UserSeeder::class);
         $this->call(SettingSeeder::class);
+        $this->call(ClientTierSeeder::class);
+        $this->call(UnitsSeeder::class);
     }
 }
diff --git a/database/seeders/UnitsSeeder.php b/database/seeders/UnitsSeeder.php
new file mode 100644
index 0000000..3670405
--- /dev/null
+++ b/database/seeders/UnitsSeeder.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Database\Seeders;
+
+use App\Models\UnitOfMeasurement;
+use Illuminate\Database\Seeder;
+
+
+class UnitsSeeder extends Seeder
+{
+    public function run(): void
+    {
+        $units = [
+            ['name' => 'Pieza', 'abbreviation' => 'u', 'allows_decimals' => false],
+            ['name' => 'Kilogramo', 'abbreviation' => 'kg', 'allows_decimals' => true],
+            ['name' => 'Litro', 'abbreviation' => 'L', 'allows_decimals' => true],
+            ['name' => 'Metro', 'abbreviation' => 'm', 'allows_decimals' => true],
+        ];
+
+        foreach ($units as $unit) {
+            UnitOfMeasurement::firstOrCreate(
+                ['name' => $unit['name']],
+                $unit
+            );
+        }
+    }
+}