Visit every room in your home (including the attic, shed and cupboards under the stairs!) And list all your belongings including curtains, kitchen equipment, luggage etc. Research how much it would cost to replace each item as new and then add up the full amount you’d need to replace everything.
We normally cover the amount you specify, however if you enter a very low amount your policy may include more than this, if this is the case you will be made aware of this before purchasing.