Define for yourself—just for you, if you want—which storage space you need in the dressing room and in what quantity. At the latest, the carpenter or, if you prefer, the person opposite you in the furniture store should get some information on how many shelves and clothes rails are required.
A brief overview of my approach:
1. Measure how many linear meters of closet space were available in the old closets.
2. Clarify whether some of the items from the old closet should go somewhere else or if something "new" needs to be included (for example: bed linen can, if you want, move out of the closet into a dresser in the bedroom. I didn’t want to keep seasonal clothes in the basement for months anymore in the new building, but have them in the closet all year round; the picnic blanket finally has space in the hallway and no longer needs to be in the wardrobe—some things can also be stored more sensibly in the hallway!)
3. Don’t just go by the pure closet size, but measure here too! Example: my T-shirts lie in stacks. Two stacks fit perfectly in 75 cm width. If the closet element is 1 m wide, it doesn’t help me because a third stack doesn’t fit next to it.
4. Don’t forget heights and lengths. We measured how high the clothes rail may be at most for me to reach comfortably. Under knee-length skirts, for example, there is still room for shelves. Under floor-length dresses, usually not. Also consider how much space you want between shelves. Stacks of clothes shouldn’t become infinitely high, but there should still be some air between the top item and the shelf above.
5. Measure depth! Those who want to lay down a lot can create storage space even with only 40 cm deep closets and at the same time optimize the space between the closets.
I then played a lot with the Pax planner to see how to get everything in the best way. You don’t have to shop at Ikea then...