Book-to-Bill Ratio

Book-to-bill ratio is new bookings signed in a period divided by revenue billed in the same period; a ratio above 1.0 indicates the firm is building backlog, while a ratio below 1.0 indicates it is drawing down contracted work.

The metric provides a leading indicator of revenue trajectory: sustained readings above 1.0 signal growing future revenue; sustained readings below 1.0 signal a firm consuming its contracted base without replacing it at the same rate.

The formula

Book-to-bill ratio = New bookings in period / Revenue billed in period

New bookings are the total contract value of agreements signed during the period, including new statements of work, change orders, and renewals. Firms differ on whether multi-year contracts are counted in full at signing or recognized as annual contract value. Consistency in the definition matters more than the choice.

Revenue billed is the amount invoiced to clients during the same period. This differs from revenue recognized, which follows accounting rules around project completion. Some firms calculate the ratio against billed revenue; others use recognized revenue. The denominator should match the firm’s standard revenue reporting.

Interpreting the ratio

A ratio of 1.0 means the firm signed exactly as much new work as it billed: the backlog is flat.

A ratio above 1.0 means the firm signed more than it billed. Backlog grows. Future revenue is accumulating ahead of current delivery capacity. Sustained readings above 1.0 signal demand health and support hiring decisions.

A ratio below 1.0 means the firm billed more than it signed. Backlog shrinks. If the ratio stays below 1.0 for several periods, the firm is consuming its contracted base. Future revenue will fall unless sales activity accelerates.

A single period below 1.0 is not a crisis. Seasonal patterns, large contract renewals clustering in certain periods, and deal timing all affect the ratio. The trend over three to six periods is more informative than any single quarter.

Limitations

Book-to-bill captures volume but not profitability. A firm can post a strong ratio by signing low-margin fixed-fee engagements or by discounting aggressively to close deals. The ratio should be read alongside margin, realization rate, and pipeline coverage to assess whether the bookings being added are worth having.

The ratio is also sensitive to the timing of large contracts. A single enterprise deal can push the ratio well above 1.0 in one quarter and leave subsequent quarters looking weak even when underlying sales activity is steady. For firms with lumpy deal flow, a trailing twelve-month view reduces noise.

Relationship to backlog

Book-to-bill and backlog tell complementary stories. Backlog is the stock of contracted but not yet billed work at a point in time. Book-to-bill is the flow: how fast the stock is growing or shrinking relative to delivery. Backlog coverage takes the stock and divides it by current revenue run rate to show how many months of work remain. Together, these three metrics give a clear picture of near-term revenue visibility.

Work in progress (WIP) aging data adds a further dimension: if WIP is aging without being billed, the firm may be carrying more contracted revenue than it is converting to invoices, which flatters the book-to-bill ratio while creating a revenue leakage risk.