“Days of supply” is calculated as:
Days = (Stock in kt / Monthly Consumption in kt) × 30
This is an estimate of consumption cover for one product.
Directive 2009/119/EC requires each member state to hold emergency stocks equivalent to at least 90 days of average daily net imports or 61 days of average daily inland consumption, whichever is greater, calculated under the Directive's own accounting rules — in crude equivalent, across all petroleum products together, with its prescribed deductions and eligible-stock definitions.
The figure above is none of those things: it is a single product measured against its own consumption. We draw a 90-day reference line on it because it is a familiar number and a useful constant, not because 90 days is a statutory minimum for any individual fuel. Nothing on this site establishes that a country complies, or fails to comply, with the Directive; that assessment belongs to the European Commission and the member states' own reporting.
What the EU average is. Each “EU average” on this site is the unweighted mean of the national days-of-cover figures: every country counts once, whatever its size, so Malta's figure moves the mean exactly as much as Germany's. It is not the EU's aggregate stock divided by the EU's aggregate consumption, which weights by volume and comes out materially lower (for the June 2026 file: petrol 58 days aggregate against 74 unweighted, diesel 79 against 94, jet 52 against 67). We publish the unweighted figure because it is what the series has always been; the label now says so. A country figure that is carried forward, modelled or capped (below) enters the mean like any other, and the note beneath each average counts how many did.
Which month a figure is from. Since 15 September 2026 (zero-policy-2026-09) a record describes the dataset's month and no other: the Eurostat cell for that month decides whether a figure is an observed value, a reported zero or not reported, and nothing older is ever promoted into the current figure. Before that, the importer scanned backwards for the latest positive value, so Lithuania's jet fuel — reported as 0.0 kt by Eurostat every month from August 2025 — was published as its July 2025 observation inside every later file. That older observation is now shown beside the current record as dated context, never as the figure.
A reported zero: cover withheld by policy. When Eurostat reports 0.0 kt with no flag, the site displays “0 kt reported” and withholdsdays of cover, a status band, and any contribution to the EU average, the counts or the rankings. This is a conservative assessment policy, not an arithmetic limitation: 0 divided by consumption is 0 days, but an unexplained zero from a country that consumes the product every month is not a number the site is willing to assert cover on. A documented resolution that confirms a genuine zero holding makes the figure assessable at 0 days; any other documented explanation leaves it withheld and says why.
Which consumption is used. Consumption is taken from the same month as the stock; if that month has no cell, from up to three earlier months, crossing absent cells only. A reported zero consumption stops the search and withholds cover for a different reason: stock divided by zero is undefined, so cover cannot be computed — arithmetic, not policy, and no resolution changes it. The raw reported zero is kept. The former fallback that modelled days from a size-class constant when no consumption was published has been retired; it measured nothing.
What a withheld figure does to the averages. Each EU average is the unweighted mean of the assessable national figures, and the coverage (“26 of 27 assessable”) is printed beside it. A mean or a count that moves because a figure was withheld or restored is a change in assessability, not in reserves, and the analysis is instructed never to present it as reserves improving or deteriorating.
The 365-day cap. Days of cover are clamped to 365. A value shown as 365 is the cap, not a measurement; the computed figure is kept alongside (provenance.uncappedDays) and the figure is labelled capped. Slovenia's jet fuel (54 kt against 4 kt a month) computes to 405 days and is shown as 365.