Law Firms by Size: The Ends Buy Partners, the Middle Makes Them

How do law firms of different sizes compare when they add partners? Sartori & Partners data show a clear split by size class. Firms of 1,000+ lawyers took 53.6% of lateral hires in the 12 months to October 2026 and made 49.9% of new partners, while firms of 400-999 lawyers made 29.5% of new partners on 23.4% of hires. The two ends of the size scale buy more than they make; the middle makes more than it buys. This sheet gives each class four lines, so a firm leader can find the class line and set the firm's own figures against it.

Two cautions apply to every line. Promotion shares cover June 2025 to May 2026, the last complete promotion month, while hiring shares run to October 2026 and count lateral arrivals at every level, not partners alone. Supply means the size of the firm a lawyer left, counted over the last 3 years. Read the gaps between lines as direction, and treat a gap of a point or so as noise.

Put the promotion share beside the hiring share and the four classes fall into two groups. Firms of 1,000+ lawyers made 49.9% of new partners against 53.6% of lateral hires, and firms under 150 lawyers made 5.5% against 9.7%. Both weigh more in the hiring market than in the promotion count. Firms of 400-999 lawyers run the other way, with 29.5% of promotions on 23.4% of hires, and firms of 150-399 lawyers tilt the same way on a smaller margin, 14.9% against 13.3%.

This is a question of tilt, not of volume. The largest class still promoted more lawyers than any other, 1,474 of the 2,955 new partners in the market. Across all classes, firms promoted 0.79 lawyers to partner for each lateral partner they hired, so buying is the bigger channel in every class; size decides by how much.

For a firm about to fill a partner seat, the class line tells the partnership what is normal. In the two middle classes a lateral partner joins beside a home-grown cohort that sets the standard. At the two ends the lateral route is routine, and more firms chase the same candidate.

The largest class supplies a little more than it takes. In the Sartori & Partners lateral database it took 52.5% of lateral hires over the last 3 years and was the previous employer of 56.6% of movers, a gap of 4.1 points, small against the size of its own hiring. The single largest flow in the market stays inside the class: moves from one firm of 1,000+ lawyers to another were 39.0% of all 12-month moves with both firm sizes known. Its median leaving rate is 14.8% a year, the highest of the four classes and above the all-firm median of 13.2%, measured on firm websites since April 2026. Turnover at that pace helps explain the buying: seats open every year, and promotion alone does not refill them.

Kirkland & Ellis, a firm of 1,000+ lawyers, heads the hirers below and carries the class pattern: its leaving rate is above the market and its time to partner shorter than the market's. Kirkland & Ellis also heads the promotion list, in the 61-100 band, so the biggest buyer is a large maker too. The list counts individual hires; lawyers who arrived as one team in the same quarter sit in the class totals but not in a firm's rank.

A firm in this class recruiting a lateral partner competes mostly with firms of its own size for lawyers from firms of its own size. Decide fast, and fund retention for senior associates: at a 14.8% median leaving rate, each year of delay adds seats that will have to be bought.

The 400-999 lawyers class shows the widest gap on the making side: 29.5% of new partners against 23.4% of lateral hires. On supply it runs the opposite way. Over 3 years it took 25.0% of lateral hires but supplied 20.3% of movers, a gap of 4.7 points, so it draws in more lawyers than it sends out. Its median leaving rate, 13.2% a year, sits close to the all-firm median.

Moore & Van Allen, a firm of 400-999 lawyers, fits the line. Its net partner flow over 12 months, lateral partners hired against partners who left for another firm, was balanced, and its time to partner is shorter than the market's.

In a midsize firm, the internal candidate is the yardstick any lateral partner will be measured by, so the business case for a hire should name that comparison. Because the class imports more lawyers than it supplies, part of its associate bench was bought; a visible promotion record is what keeps those hires through the partnership vote.

With 14.9% of promotions on 13.3% of hires, this class sits on the making side by a narrow margin. Pace and retention set it apart. Over the last 5 years, 27.1% of its new partners reached the title within 8 years of starting practice, against 23.2% across the market and 22.4% at firms of 400-999 lawyers. Its median leaving rate, 11.9% a year, is the lowest of the four.

On supply the class is a smaller importer than the one above it, taking 13.9% of lateral hires over 3 years and supplying 11.7% of movers. Calfee, Halter & Griswold, a firm of 150-399 lawyers, recorded a positive net partner flow over 12 months, hiring more lateral partners than it saw leave for other firms, with a leaving rate in line with the market.

A firm in this class has a concrete pitch for senior associates at larger firms: an earlier route to partner and colleagues who tend to stay. A larger firm hiring partners out of this class should expect candidates who reached the title earlier in their careers than its own cohort, and settle how that seniority counts before the offer.

Sartori & Partners data show the smallest class supplying the most lawyers relative to the hiring it does. Over the last 3 years, firms under 150 lawyers were the previous employer of 11.4% of lawyers who moved, against 8.6% of lateral hires taken, a gap of 2.8 points. Their 12-month hiring share, 9.7%, matches the 3-year pattern, and they made 5.5% of new partners. Turnover does not explain the outflow: their median leaving rate is 12.7% a year, below the all-firm 13.2%.

The comparison carries the whole sheet: the two middle classes hire more than they supply, and the two ends supply more than they hire, the smallest by the widest margin for its size: over 3 years it supplied 1.3 times its own hiring share. With few partners made at home, 5.5% of the market total, senior lawyers at small firms who want the title often appear to move to get it. For any firm searching for lateral talent, this is the deepest bench relative to the hiring it absorbs.

At a firm of 1,000+ lawyers, your class takes 53.6% of lateral hires and sheds lawyers at a median 14.8% a year. Treat lateral partner hiring as a standing budget line and judge it on who is still there after two years, not on arrivals.

At a firm of 400-999 lawyers, your class made 29.5% of new partners. Show that record to the associates you recruit: your class takes in more lawyers than it supplies, and the promotion path is what holds them.

At a firm of 150-399 lawyers, lead with pace. 27.1% of your class's partners got there within 8 years, and a median leaving rate of 11.9% is evidence that people stay.

At a firm under 150 lawyers, your class supplies 11.4% of the lawyers who move. Expect to add seniority by hiring, expect larger firms to call your senior associates, and give them a dated partnership timetable before someone else gives them an offer. The class lines rest on public law-firm announcements, firm websites and professional profiles, checked monthly by Sartori & Partners; set your own hiring, promotion and leaving figures beside your line before the next partnership round.