Class A office is the highest tier in the standard office building classification, defined by BOMA International as the most prestigious buildings competing for premier tenants with rents above the area average. These buildings feature high-quality finishes, modern systems, strong accessibility, and a defined market presence, and they command the market's top rents.
What Is a Class A Office Building
A Class A office building is a top-tier property that competes for premier tenants on quality, location, and prestige, at rents above the area average. BOMA International, which maintains the standard, defines it as buildings with high quality finishes, state of the art systems, exceptional accessibility, and a definite market presence. The grade is relative to each market.
Because the grade is relative, a Class A building in a secondary market may carry finishes and rents a primary market would grade as Class B. Classification is set by brokers and appraisers judging the building against its own market's stock, weighing age, location, systems, amenities, and rent. There is no certifying authority, so the label is a market consensus rather than a fixed spec, and it shifts as new supply resets the top of the market.
Attribute | Typical Class A profile |
Location | Prime CBD or premier suburban node |
Age or renovation | New or recently renovated to current standards |
Finishes and systems | High-end finishes, modern mechanical and life-safety systems |
Amenities | On-site retail, fitness, security, often LEED certification |
Rent | Above the area average |
Why Class A Office Matters
Class A office matters because it concentrates tenant demand and rent premium, and has diverged sharply from lower grades. CBRE reported national downtown Class A vacancy at 15.4 percent in the third quarter of 2025, its lowest in three years, while trophy buildings, the top of Class A, fell to 10.4 percent. Lower-grade space lagged.
For an operator, the grade drives the entire underwrite: rent, tenant credit, capital needs, and exit. Class A commands the top rents and the strongest covenants, but it also carries the highest fit-out and amenity cost to hold the grade. The flight to quality, tenants concentrating in the best space, means a well-located Class A asset can gain occupancy while the broader market softens, and a slipping Class A asset that stops reinvesting can quietly grade down to Class B.
Example
The Class A premium is measured as the rent gap over lower grades. CBRE reported the U.S. average asking office rent at 37.21 dollars per square foot in the first quarter of 2026, and market data has shown Class A rents running roughly 84 percent above non-prime Class B and C space.
Input | Value |
Class B/C base rent | 24.00 per sq ft |
Class A premium | 84% |
Class A rent | 24.00 x 1.84 = 44.16 per sq ft |
Premium per sq ft | 20.16 per sq ft |
Annual premium on 50,000 sq ft | 20.16 x 50,000 = 1,008,000 |
A 50,000 square foot tenant pays about 1.0 million dollars per year more for Class A than for Class B or C space at these representative rents. That premium is the rent the operator must justify with location, finishes, and amenities, and the gap the tenant weighs against the cost of a lesser building.
Variations and Edge Cases
Variant | What changes |
Trophy | The top slice of Class A; landmark assets with the lowest vacancy and highest rents |
Class A minus | Older or less-amenitized Class A; graded down within the tier |
Market-relative grade | The same building can be Class A in a secondary market, Class B in a primary one |
Grade drift | A Class A asset that stops reinvesting can slip to Class B over time |
Class A Office vs Class B Office
Class A office is often confused with Class B office. Class A is the top tier: prime location, modern systems, high-end finishes, and above-average rents, targeting premier tenants. Class B is functional, well-maintained space with average finishes and rents, often older or in secondary locations, targeting cost-conscious tenants. The line is relative to each market and set by broker and appraiser consensus, not a certifying body, so a Class B building in a top market can out-spec a Class A building elsewhere. Class A carries the rent premium and the reinvestment cost; Class B trades lower rent for lower carrying cost.
Frequently Asked Questions
What defines a Class A office building?
A Class A office building is defined by BOMA International as the most prestigious buildings competing for premier tenants with rents above the area average, featuring high quality finishes, state of the art systems, exceptional accessibility, and a definite market presence. The grade is relative to each market, not an absolute specification.
How much more does Class A office rent cost?
Class A office commands the market's top rents, with data showing Class A running roughly 84 percent above non-prime Class B and C space. At a 24 dollar Class B base, that implies about 44 dollars per square foot for Class A, a premium near 1 million dollars per year on a 50,000 square foot lease.
Who decides a building's office class?
No certifying authority assigns office class. Brokers and appraisers set the grade by market consensus, judging a building against its own market's stock on age, location, systems, amenities, and rent. Because the grade is market-relative, the same building can be Class A in one market and Class B in another.
Related Terms
Job Growth
Demographic Analysis
Absorption