diff --git a/app/Filament/User/Resources/BatchResource.php b/app/Filament/User/Resources/BatchResource.php
index 5c5fff3..de742db 100644
--- a/app/Filament/User/Resources/BatchResource.php
+++ b/app/Filament/User/Resources/BatchResource.php
@@ -4,11 +4,13 @@ namespace App\Filament\User\Resources;
 
 use App\Filament\User\Resources\BatchResource\Pages;
 use App\Models\Batch;
+use App\Models\ProductSize;
 use App\Models\Recipe;
 use Filament\Forms;
 use Filament\Forms\Form;
 use Filament\Forms\Get;
 use Filament\Resources\Resource;
+use Illuminate\Support\HtmlString;
 use Filament\Tables;
 use Filament\Tables\Table;
 
@@ -38,6 +40,17 @@ class BatchResource extends Resource
                     ->searchable()
                     ->preload()
                     ->required()
+                    ->live()
+                    ->afterStateUpdated(fn ($set) => $set('size_id', null)),
+
+                Forms\Components\Select::make('size_id')
+                    ->label('Variante (Verpackung)')
+                    ->options(fn (Get $get) => ProductSize::with('packing')
+                        ->where('product_id', $get('product_id'))
+                        ->get()
+                        ->mapWithKeys(fn ($s) => [$s->id => $s->packing->name . ' ' . $s->packing->size . 'g'])
+                    )
+                    ->required()
                     ->live(),
 
                 Forms\Components\Select::make('recipe_id')
@@ -48,6 +61,25 @@ class BatchResource extends Resource
                     ->required()
                     ->live(),
 
+                Forms\Components\TextInput::make('units_produced')
+                    ->label('Anzahl Einheiten')
+                    ->numeric()
+                    ->required()
+                    ->live(debounce: 400),
+
+                Forms\Components\Placeholder::make('quantity_g_preview')
+                    ->label('Gesamtgewicht (berechnet)')
+                    ->content(function (Get $get): HtmlString {
+                        $units = (int) $get('units_produced');
+                        $sizeId = $get('size_id');
+                        if (! $units || ! $sizeId) {
+                            return new HtmlString('<span class="text-gray-400">—</span>');
+                        }
+                        $size = ProductSize::with('packing')->find($sizeId);
+                        $totalG = $units * ($size?->packing?->size ?? 0);
+                        return new HtmlString("<strong>{$totalG} g</strong> ({$units} × {$size?->packing?->size}g)");
+                    }),
+
                 Forms\Components\DatePicker::make('produced_at')
                     ->label('Produktionsdatum'),
 
diff --git a/app/Filament/User/Resources/ProductResource/RelationManagers/BatchesRelationManager.php b/app/Filament/User/Resources/ProductResource/RelationManagers/BatchesRelationManager.php
index bf3726e..9d8dcc5 100644
--- a/app/Filament/User/Resources/ProductResource/RelationManagers/BatchesRelationManager.php
+++ b/app/Filament/User/Resources/ProductResource/RelationManagers/BatchesRelationManager.php
@@ -2,11 +2,14 @@
 
 namespace App\Filament\User\Resources\ProductResource\RelationManagers;
 
+use App\Models\ProductSize;
 use Filament\Forms;
 use Filament\Forms\Form;
+use Filament\Forms\Get;
 use Filament\Resources\RelationManagers\RelationManager;
 use Filament\Tables;
 use Filament\Tables\Table;
+use Illuminate\Support\HtmlString;
 
 class BatchesRelationManager extends RelationManager
 {
@@ -24,6 +27,16 @@ class BatchesRelationManager extends RelationManager
                 ->unique(ignoreRecord: true)
                 ->maxLength(255),
 
+            Forms\Components\Select::make('size_id')
+                ->label('Variante (Verpackung)')
+                ->options(fn () => ProductSize::with('packing')
+                    ->where('product_id', $this->getOwnerRecord()->id)
+                    ->get()
+                    ->mapWithKeys(fn ($s) => [$s->id => $s->packing->name . ' ' . $s->packing->size . 'g'])
+                )
+                ->required()
+                ->live(),
+
             Forms\Components\Select::make('recipe_id')
                 ->label('Rezeptur')
                 ->relationship('recipe', 'name')
@@ -31,6 +44,25 @@ class BatchesRelationManager extends RelationManager
                 ->preload()
                 ->required(),
 
+            Forms\Components\TextInput::make('units_produced')
+                ->label('Anzahl Einheiten')
+                ->numeric()
+                ->required()
+                ->live(debounce: 400),
+
+            Forms\Components\Placeholder::make('quantity_g_preview')
+                ->label('Gesamtgewicht (berechnet)')
+                ->content(function (Get $get): HtmlString {
+                    $units = (int) $get('units_produced');
+                    $sizeId = $get('size_id');
+                    if (! $units || ! $sizeId) {
+                        return new HtmlString('<span class="text-gray-400">—</span>');
+                    }
+                    $size = ProductSize::with('packing')->find($sizeId);
+                    $totalG = $units * ($size?->packing?->size ?? 0);
+                    return new HtmlString("<strong>{$totalG} g</strong> ({$units} × {$size?->packing?->size}g)");
+                }),
+
             Forms\Components\DatePicker::make('produced_at')
                 ->label('Produktionsdatum'),
 
@@ -84,6 +116,10 @@ class BatchesRelationManager extends RelationManager
                     ->searchable()
                     ->sortable(),
 
+                Tables\Columns\TextColumn::make('units_produced')
+                    ->label('Einheiten')
+                    ->suffix(fn ($record) => $record->quantity_g ? ' (' . number_format($record->quantity_g, 0, ',', '.') . 'g)' : ''),
+
                 Tables\Columns\TextColumn::make('recipe.name')
                     ->label('Rezeptur'),
 
diff --git a/app/Models/Batch.php b/app/Models/Batch.php
index a3a7fd6..0168302 100644
--- a/app/Models/Batch.php
+++ b/app/Models/Batch.php
@@ -6,7 +6,10 @@ use Illuminate\Database\Eloquent\Model;
 
 class Batch extends Model
 {
-    protected $fillable = ['lot_number', 'product_id', 'recipe_id', 'produced_at', 'expires_at'];
+    protected $fillable = [
+        'lot_number', 'product_id', 'size_id', 'recipe_id',
+        'units_produced', 'quantity_g', 'produced_at', 'expires_at',
+    ];
 
     protected $casts = [
         'produced_at' => 'date',
@@ -18,6 +21,11 @@ class Batch extends Model
         return $this->belongsTo(Product::class);
     }
 
+    public function size()
+    {
+        return $this->belongsTo(ProductSize::class);
+    }
+
     public function recipe()
     {
         return $this->belongsTo(Recipe::class);
@@ -27,4 +35,61 @@ class Batch extends Model
     {
         return $this->hasMany(BatchOrigin::class);
     }
+
+    protected static function booted(): void
+    {
+        // Auto-calculate quantity_g before saving
+        static::saving(function (Batch $batch) {
+            if ($batch->units_produced && $batch->size_id) {
+                $gramsPerUnit = $batch->size?->packing?->size ?? 0;
+                $batch->quantity_g = $batch->units_produced * $gramsPerUnit;
+            }
+        });
+
+        static::created(function (Batch $batch) {
+            $batch->deductSpices();
+        });
+
+        static::updated(function (Batch $batch) {
+            if ($batch->wasChanged(['recipe_id', 'size_id', 'units_produced'])) {
+                $batch->restoreSpices(
+                    $batch->getOriginal('recipe_id'),
+                    $batch->getOriginal('quantity_g'),
+                );
+                $batch->deductSpices();
+            }
+        });
+
+        static::deleting(function (Batch $batch) {
+            $batch->restoreSpices($batch->recipe_id, $batch->quantity_g);
+        });
+    }
+
+    private function deductSpices(): void
+    {
+        if (! $this->quantity_g || ! $this->recipe_id) {
+            return;
+        }
+
+        $recipe = Recipe::with('spices')->find($this->recipe_id);
+
+        foreach ($recipe->spices as $spice) {
+            $grams = $this->quantity_g * $spice->pivot->amount_in_percent / 100;
+            $spice->decrement('quantity', $grams);
+        }
+    }
+
+    private function restoreSpices(int $recipeId, float $quantityG): void
+    {
+        if (! $quantityG || ! $recipeId) {
+            return;
+        }
+
+        $recipe = Recipe::with('spices')->find($recipeId);
+
+        foreach ($recipe->spices as $spice) {
+            $grams = $quantityG * $spice->pivot->amount_in_percent / 100;
+            $spice->increment('quantity', $grams);
+        }
+    }
 }
diff --git a/database/migrations/2026_09_12_033131_add_production_fields_to_batches.php b/database/migrations/2026_09_12_033131_add_production_fields_to_batches.php
new file mode 100644
index 0000000..09c731d
--- /dev/null
+++ b/database/migrations/2026_09_12_033131_add_production_fields_to_batches.php
@@ -0,0 +1,29 @@
+<?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('batches', function (Blueprint $table) {
+            $table->foreignId('size_id')->nullable()->after('product_id')
+                  ->constrained('products_sizes')->nullOnDelete();
+            $table->unsignedInteger('units_produced')->nullable()->after('size_id');
+            $table->decimal('quantity_g', 10, 2)->nullable()->after('units_produced');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('batches', function (Blueprint $table) {
+            $table->dropForeign(['size_id']);
+            $table->dropColumn(['size_id', 'units_produced', 'quantity_g']);
+        });
+    }
+};