Absorption is the rate at which available commercial space is occupied over a defined period. Gross absorption measures all space leased in the period, regardless of whether tenants vacated other space simultaneously.
Net absorption (gross absorption minus space returned to the market through move-outs, downsizings, and lease terminations) is the metric that tells practitioners whether a market is actually tightening or merely churning. Positive net absorption means demand is consuming supply; negative net absorption means supply is outpacing demand even if headline leasing activity looks healthy.
Conflating the two is one of the most common errors in market analysis.
Brokers and market analysts track quarterly net absorption by submarket and product type, with data reported by CoStar Group, CBRE Research, JLL, Cushman & Wakefield, and Colliers. Absorption rate (available inventory divided by average monthly net absorption) expresses the market in months of supply.
A submarket with 2 million square feet of available space and 200,000 SF of average monthly net absorption has 10 months of supply; a submarket with the same inventory but 50,000 SF of monthly absorption has 40 months. That difference in lease-up horizon drives fundamentally different underwriting assumptions for new development.
The forward-looking character of net absorption makes it more valuable for underwriting than point-in-time vacancy. A market reporting 15% vacancy but accelerating net absorption signals improving fundamentals ahead; rents and occupancy are likely to recover.
A market at 8% vacancy with decelerating or negative net absorption signals deteriorating fundamentals; vacancy is about to climb. Experienced underwriters read the trend in quarterly net absorption to calibrate whether their stabilization assumptions are conservative or optimistic relative to current market momentum.
Construction lenders formalize the absorption signal through pre-leasing thresholds and stabilization timeline assumptions. Most construction lenders require 50-70% pre-leasing for speculative office before funding a construction loan; industrial lenders may accept 0% pre-leasing for in-demand spec product in low-vacancy markets or require 100% for build-to-suit.
The stabilization period (time between construction completion and the underwritten stabilized occupancy) is modelled using market absorption rates and directly affects the loan's interest reserve sizing, the equity return timeline, and the permanent lender's takeout commitment. The absorption assumption is frequently the most leveraged variable in a development pro forma: an overly optimistic absorption rate can make an infeasible project appear to pencil.