class Category(models.Model):

    category = models.CharField(max_length=100)

    def __str__(self):
        return self.category

    class Meta:
        verbose_name_plural = "categories"

class Post(models.Model):
    title = models.CharField(max_length=100)
    category = models.ForeignKey(Category, on_delete=models.CASCADE )
    content = RichTextUploadingField()
    date_posted = models.DateTimeField(default=timezone.now)

Post.objects.values('category').order_by('category').annotate(the_count=Count('category'))

<QuerySet [{'category': 2, 'the_count': 5}, {'category': 3, 'the_count': 4}]>

<QuerySet [{'category': "fashion", 'the_count': 5}, {'category': "travel", 'the_count': 4}]>