Growth Blog Topic

EBITDA & Margin Math

Translating AI investment into profit terms for firm owners. Revenue created, margin kept, the two-number test, and what to measure in the first 90 days of any AI system.

Definition

EBITDA and margin math is the discipline of pricing AI investment in profit terms instead of time saved. An AI system pays when it creates revenue the firm would not otherwise have won or protects margin the firm would otherwise have lost. Deltek’s industry study found professional-services EBITDA fell from 15.4% to 9.8% over five years, which is the pressure this math answers.

Point of View

Why NorthSignal is writing about this.

NorthSignal uses this topic to keep AI conversations anchored to the P&L. Every build is sized against the revenue and margin it should move, so the field notes show owners how to run that math before buying anything, from anyone.

Core Questions

Questions this topic will answer.

Each answer is written as a standalone capsule so readers and AI systems can understand the concept without needing surrounding context.

Question 01

How should a firm owner evaluate the return on AI?

A firm owner should evaluate AI in two movements. Revenue created, meaning engagements, reactivations, and referrals the system produced that would not have happened otherwise. And margin kept, meaning owner and partner hours pulled out of non-billable growth work and returned to delivery or sales. If neither number moves within a defined window, the system did not pay.

Question 02

Why is time saved a weak metric for AI?

Time saved is a weak metric because saved hours do not appear on a P&L. A tool can save ten hours a week while revenue and margin stay exactly where they were, because the recovered time gets absorbed instead of redeployed. Profit terms force the harder question of what the hours became.

Question 03

What is the two-number test for an AI investment?

The two-number test asks an owner to write down the revenue an AI system should create and the margin it should protect within a defined window, usually 90 days. If the vendor cannot help fill in both numbers before the build starts, the purchase is a cost rather than an investment.

Question 04

What should a firm measure in the first 90 days?

In the first 90 days a firm should measure pipeline movement the system touched, dormant customers reactivated, proposals and follow-ups shipped against the prior baseline, and owner hours returned to billable work. Each measure ties back to revenue created or margin kept, which keeps the review honest.

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