The figure first: Rocket Lab reported remaining backlog of $1,066,946 thousand — roughly $1.07 billion — as of March 31, 2025, in its Q1 2025 Form 10-Q. Crossing a billion in backlog is a milestone worth stating precisely, because the company's own definition is precise: backlog represents the estimated revenue from enforceable agreements that has not yet been recognized.
Backlog is forward revenue, not guaranteed revenue. A contract enters backlog when an enforceable agreement exists, and it leaves backlog as the work is performed and revenue is recognized. That means a billion in backlog is a pipeline indicator, not a bank balance — and the rate at which it converts is governed by program timing and the company's ability to deliver missions and hardware on schedule.
The durability question is answered by the concentration disclosure. In its FY2024 Form 10-K, Rocket Lab noted that its top five backlog customers accounted for approximately 69% of backlog, and that its largest customers together represented roughly 51% of revenue. A year later, the FY2025 Form 10-K put top-five backlog concentration at approximately 77%. Concentration cuts both ways: it signals anchor demand, but it also means a single program slip or cancellation moves the whole line.
So the honest read is a backlog above $1 billion that is real, enforceable and increasingly concentrated. For a book-to-bill watcher, the next thing to track is whether new bookings refill the line faster than recognition draws it down — and whether that top-five share keeps climbing. The underlying filings are on sec.gov; the discovery layer is EdgarBeast.