How the TrovaStorage price index is calculated

The rules

1. Only prices read on the operator's site or supplied by the operator count, each with its source and the day it was read. No estimate, no price we calculated and no offer made to one customer counts.
2. Promotions are excluded: a discount on the first month is not the unit's price.
3. A price read more than 90 days before the release is excluded until somebody reads it again.
4. Square metres only. A price per cubic metre, such as a mover's depository quotes, is not converted and is not in these tables: the two units are never mixed.
5. Every price is brought to euros per month: a daily price is multiplied by 365/12, a weekly one by 52/12. Of a “from … to …” range the lower value counts.
6. The price per square metre is the unit's price divided by its floor area; a price published per square metre is multiplied by the area to give the unit's price.
7. The size is the rung of the size ladder the unit's area falls in: the largest one not above it.
8. Each facility counts once per size, with its lowest price.
9. For each city and size the table gives the lowest price, the median and the highest across facilities, the number of facilities and operators, and how the sources state VAT and insurance.
10. A figure is published only with at least 3 facilities of at least 2 operators. Below that the table says “not available”.
11. A release stays as it is: a month's figures are not rewritten.

The size ladder

In square metres: 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 25, 30, 40, 50, 75, 100, 150, 200, 300, 400.

What the index is not

• It is not a facility's price: that is on the facility's page, with its source.
• It is not a quote: the facility gives the final price.
• It cannot be downloaded as a file: the tables are on these pages.