Benchmarking Legal AI Spend Against Revenue: Industry Data for 2025

Legal AI spend benchmarking is an emerging discipline — the data is more recent and more variable than established legal technology categories like e-billing or document management. But the data that exists provides useful reference points for firms trying to calibrate their AI investment relative to their revenue base and competitive context.

Reviewing Am Law 100 spending patterns

Thomson Reuters' annual legal technology spending research shows that Am Law 100 firms are investing 1.5-2.5% of revenue in legal technology broadly, with AI-specific investment representing an increasingly large share of that total. In absolute terms, the Am Law 100 median AI investment in 2024 was in the $2-5 million range, with the highest investors — Kirkland, Latham, and a handful of others — at levels multiples higher.

These figures include both software licensing and the implementation and engineering costs that represent the majority of total AI program cost.

Analyzing mid-market investment levels

Mid-market firms ($100M-$500M revenue) are investing at lower absolute levels but comparable percentages — typically 0.8-1.5% of revenue in legal technology, with AI representing 20-40% of that total. For a $200M revenue firm, that implies $400,000-$800,000 per year in legal AI investment — a range that encompasses meaningful program spend but falls well short of the Am Law 100 leaders.

Benchmarking in-house legal department AI spending

In-house legal departments, as measured by CLOC's annual benchmarking, are investing at lower percentage levels than law firms — typically 0.3-0.8% of total legal department operating budget — but the trend line is upward. CLOC's data shows that legal departments with above-median AI investment also show above-median efficiency metrics (cost per matter, cycle time) and above-median client satisfaction scores from business stakeholders.

The correlation between AI investment and operational performance, while not perfectly causal, is consistent enough to support the investment case.

Implications of low AI investment levels

The practical implication of these benchmarks is that firms and legal departments at the lower end of the investment range — below 0.5% of revenue for law firms, below 0.3% of budget for legal departments — are likely underinvesting relative to their peers and accumulating a capability gap that will be more expensive to close later than to address now.