A double-page spread is one ad across two facing pages, so it looks like a single wide image. The Reykjavik Grapevine and Fiji Sun both sell it as inside spreads.
How it's sold
Both sell it through their sales teams. You book an issue and a position, and the publisher confirms the artwork size.
What it costs
Most publishers quote this on request, and the usual basis is a flat fee per placement.
What you supply
You supply one print-ready file at the full spread size, with the fold in the middle in mind.
Best for
It suits launches and campaigns where you want a big visual impact in one issue.
Before you buy
Keep key text and logos away from the central fold and ask for the exact bleed sizes.