What it means
Revenue tells you what a company delivered last quarter, which is history. Bookings tell you what customers have committed to buy, which is closer to the future, and the book-to-bill ratio puts those two numbers side by side in a single figure.
A ratio of exactly 1.0 means new orders matched invoiced work, so the backlog is stable. Above 1.0 the order book is filling up faster than the factory can empty it, and below 1.0 the company is consuming backlog it built earlier, which eventually shows up as falling revenue.
Investors watch the ratio closely in cyclical industries because it moves before the income statement does. A semiconductor equipment maker can report record revenue while its book-to-bill quietly slips to 0.8, and that combination usually signals that the following two or three quarters will be considerably weaker.
Managers use it internally for capacity planning and hiring. A sustained ratio of 1.2 says the business needs more people, more shifts or more subcontracting, whereas a run of 0.9 readings is the signal to slow recruitment before the payroll outruns the workload.
The main pitfall is definitional. Companies differ on when an order counts as booked and whether cancellations are netted off, so a single quarter's ratio can be distorted by one very large contract or by a change in booking policy rather than by any real change in demand.
In practice
Real-world examples.
Example
A maker of industrial pumps reports quarterly bookings of $22,000,000 against billings of $20,000,000, giving a ratio of 1.10. Management uses that reading to justify adding a second assembly shift rather than turning work away.
Example
A defence electronics supplier posts a ratio of 0.75 after a large government programme is deferred. Revenue that quarter still looks healthy because it is drawing down backlog, but the board immediately freezes discretionary spending in anticipation of a thinner year ahead.
Example
A commercial furniture manufacturer tracks book-to-bill monthly rather than quarterly. When three consecutive months come in below 0.9, the sales director redirects the team towards refurbishment contracts with shorter lead times to refill the order book.
Formula
Calculation
Book-to-bill ratio = value of orders booked in the period / value of orders billed in the period
Take an industrial automation supplier reporting its quarter. It booked $9,600,000 of new orders and invoiced $8,000,000 of shipments, so the ratio is $9,600,000 / $8,000,000 = 1.20.
The backlog effect follows directly. Opening backlog was $5,000,000, and closing backlog is $5,000,000 + $9,600,000 - $8,000,000 = $6,600,000, an increase of $1,600,000 or 32% on the opening figure.
Read that together and the picture is clear: for every $1.00 the company shipped, customers ordered $1.20, and the factory now has roughly ten months of work in hand at the current billing rate, since $6,600,000 / ($8,000,000 / 3 months) = 2.475 quarters.Case study
Seen in the real world.
Ridgefield Optics is an invented company used here as an illustrative example only. It supplied precision lenses to instrument makers, and for six straight quarters its book-to-bill ratio sat between 1.15 and 1.30, so it doubled its polishing capacity and hired 40 additional technicians.
In the seventh quarter, revenue hit a record $31,000,000 and the board was in a celebratory mood. The finance director pointed out that bookings had been only $21,700,000, giving a book-to-bill of $21,700,000 / $31,000,000 = 0.70, and that the backlog had fallen by $9,300,000 in a single quarter.
Because the warning came from bookings rather than revenue, this illustrative company had roughly two quarters of notice. It paused the third expansion phase, moved contract staff off the payroll and renegotiated raw material commitments, and when revenue finally fell the following year the business remained profitable rather than being caught with a factory built for demand that had already gone.
Watch out
Common mistakes.
- Reading one quarter's ratio in isolation. A single large order or a single deferred shipment can swing the figure dramatically, so the trend over three or four periods carries the real signal.
- Treating a ratio above 1.0 as unambiguously good news. A very high reading can mean the company simply cannot ship fast enough, which frustrates customers and invites competitors in.
- Comparing the ratio across different industries. Booking conventions and lead times vary so much that a 1.05 in shipbuilding and a 1.05 in consumer electronics describe completely different situations.
Questions
People also ask.
What counts as a booking?
Usually a firm, non-cancellable customer order with agreed pricing and a delivery date, though each company defines it in its own accounting policy and definitions do drift.
Does book-to-bill work for service businesses?
Yes, provided the business has signed contracts with defined values, so consultancies and engineering firms often track a signings-to-revenue ratio that behaves the same way.
Is book-to-bill the same as backlog coverage?
No, book-to-bill measures flow in a period, whereas backlog coverage measures how many months of work the existing order book represents.
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