Rent a storage unit: The comprehensive guide to calculating the right size

When you are looking for a storage unit that fits your needs, choosing the right size is what makes the difference between space well used and money wasted. A reasonably accurate calculation makes sure everything you put into storage actually fits, while stopping you from paying for square metres you will never use.

Rule of thumb: you need roughly 10% – 15% of your living space

The average Spanish home is around 90 m², so most full moves and clear-outs are covered by a unit of roughly 9 to 13 m². If you only want to free up space at home rather than empty it completely, 2 to 3 m² is usually plenty.

Find out how much space you need: just read it off the table

Storage units are usually between 2 and 3 metres high, and every household has a different volume. We have put together a table showing roughly how big a unit needs to be, depending on your living situation. Note that Spanish flats are described by their number of bedrooms (dormitorios), which is how the table is ordered — unlike Germany, Austria or Switzerland, where the count includes the living room. The unit "wardrobes (60 x 85 x 200 cm)" is only partly helpful — almost nobody stores 35 wardrobes — but it helps you picture the actual size of the room. A standard moving box takes up about 0.05 m³, so if your whole household fits into boxes, a 2 m² (roughly 5 m³) unit already holds 100 perfectly stacked boxes.

	Area in m²	Volume in m³	Equivalent in wardrobes
Small trastero or altillo	1–1.5	3–5	1
A few pieces of furniture or boxes	2–2.5	5–8	5
Studio	2.5–3.5	8–11	8
1-bedroom flat	3.5–5.5	11–15	11
2-bedroom flat	5.5–8.5	15–25	15
3-bedroom flat	8.5–15	25–35	25
House or 4+ bedrooms	15–20	35–50	35

Why does the size of the storage unit matter?

The right storage unit depends on several factors: the number and type of items you want to store, and your own preferences. A unit that is too small turns into chaos and forces you to unpack half of it every time you need something from the back. A unit that is too large, on the other hand, drives up your costs for no reason — a self storage box in Spain costs €22,00 per m² per month on average, so every extra square metre shows up on the invoice. You can find the full breakdown in our guide to what a storage room costs in Spain.

The benefits of getting the size right

Choosing the right size has several advantages. By using the space efficiently you save money, because you only pay for what you actually use. On top of that, the right size lets you organise things properly and reach your belongings without having to empty half the unit first.

Step by step: calculating the perfect storage size

1. Take an inventory of your belongings

Start with an inventory of everything you want to store. Go room by room and note down all the larger items: furniture, appliances, sports equipment and anything else bulky. Also count the boxes or containers you plan to store.

2. Sort the items into categories

Group your things into categories to get a clearer picture. You can sort them by size, weight or how often you use them. This makes it much easier to estimate the space each group needs.

3. Think about access and organisation

When you calculate the space you need, think about how you will get to your things and organise them. If you need to reach certain items regularly, make sure there is enough room to move around comfortably — store those items near the door. Plan how you will stack, too: going upwards is the simplest way to gain square metres.

4. Calculate the space you need

Based on the previous steps you can now work out the size you need. Allow enough room for the whole household plus the space required to reach the things you use often. The table at the top of this article already gives you a solid starting point.

What to know about renting storage in Spain

The trastero that came with the flat rarely covers it

Many Spanish flats include a communal trastero in the basement or an altillo above the hallway, but these are usually only 2 to 4 m². For a full move or a clear-out they fall short, which is why a rented box normally complements them rather than replacing them.

Guardamuebles is quoted by volume, not by surface

If you are also getting quotes from a traditional guardamuebles, have the m³ figure ready rather than the m². Moving companies price by volume or per container, while self storage is billed per m². The m³ column in the table above is exactly what you need for that quote.

Damp on the coast, heat inland

Along the northern coast, Galicia and the whole Mediterranean seaboard, humidity is the main threat to clothes, documents and wooden furniture. Inland, the problem is the opposite: very hot summers, which affect candles, electronics, vinyl and instruments. If you are storing anything delicate, choose a climate-controlled box and leave a few centimetres of air between your boxes and the walls — budget for that margin when you calculate the size.

Watch out for IVA

Unlike residential rent, renting a trastero is subject to 21% IVA in Spain. Always check whether the advertised price already includes it before you compare offers — a slightly larger box may be a better deal than it first looks, or the other way round.

Finding the right storage unit

Once you know how much space you need, all that is left is to find an available storage unit near you in the right size. The best way to do that is storabble — the only independent comparison platform for storage space. Here is a quick overview of the most important cities:

Spain	More cities
– Storage in Madrid – Storage in Barcelona – Storage in Valencia – Storage in Seville	– Storage in Málaga – Storage in Zaragoza – Storage in Bilbao

Frequently asked questions