Self-Storage Unit Sizes Explained: What Fits in Each

The most expensive mistake in self-storage is renting the wrong size — too big and you pay every month for empty air; too small and you cannot fit what you came for. This guide explains how storage sizes work in South Africa, what realistically fits in each, and a simple method to size your unit before you book.

How storage is measured

Self-storage is usually sold by floor area in square metres (m²), but the number that really matters is volume — because you store upwards as well as outwards. Flexistore units are 2.3–2.4 m tall, which means even a small footprint holds a surprising amount if you stack and pack well.

A useful anchor: a 1 m² unit holds roughly 15 standard moving boxes when you use the height. Keep that "15 boxes per square metre" rule in mind and sizing becomes much easier.

A practical size guide

Use this as a starting point, then confirm with the in-app size calculator:

• Around 1 m² (≈ 15 boxes). Boxes, suitcases, files, seasonal clothes, student term-break storage, a few small items.
• A few square metres. The contents of a single room — a bedroom or a bachelor flat: bed, drawers, boxes and a few appliances.
• Mid-sized. A one- to two-bedroom home's worth of furniture and boxes.
• Larger units. A multi-room household, or a meaningful amount of business stock and equipment.

Because exact dimensions vary by facility, treat these as guides and check the live sizes available at your chosen location.

A simple method to size your unit

1. Box everything you can. Count the boxes — that gives you a baseline (remember ~15 boxes per m²).
2. List the big items separately. Bed, couch, fridge, washer, wardrobe, table.
3. Plan to stack. Heavy and sturdy on the bottom, lighter and fragile on top; use the full 2.3–2.4 m height.
4. Leave a small aisle if you will need to reach items regularly.
5. Round up one notch only if you are between sizes — and remember you can change later.

Use the in-app size calculator

Flexistore's app includes a size calculator that estimates the space you need from the items you plan to store — quicker and more reliable than guessing. And if you get it wrong, you can change unit size with no admin fee (subject to availability), so you are never stuck paying for the wrong space.

Don't over-rent

Over-renting is the quiet budget-killer of self-storage. Two habits prevent it:

• Declutter first. Store only what you will genuinely use again — see our decluttering guide.
• Pack to use the height. Good packing can drop you a whole size. See how to pack a storage unit.

What it costs

Price scales with size, so right-sizing is also cost control. There is no deposit and a one-month minimum at Flexistore, with live prices per size on the Prices page. For the full picture, see our cost guide.

Frequently asked questions

What size storage unit do I need? Box what you can and count the boxes (about 15 per m²), list big items separately, and plan to stack to the 2.3–2.4 m height. The in-app size calculator turns that into a recommended size.

How much fits in a 1 m² unit? Roughly 15 standard moving boxes if you use the height.

Can I change size later? Yes — Flexistore lets you change unit size with no admin fee, subject to availability.

Are units measured in m² or m³? Floor area is given in m², but think in volume: units are 2.3–2.4 m tall, so the usable space is larger than the footprint suggests.

Find the right size and see the price

Use the in-app calculator, then book the size that fits — no deposit, one-month minimum.

View sizes and prices →