These tables provide (or Btu/h·ft²) ranges for total cooling loads based on building type and glazing percentage.

The 400 sq ft/ton Rule is Dead: How to Use ASHRAE Fundamentals to Sanity Check Your Cooling Loads

Open your ASHRAE Handbook—Fundamentals. In the current edition (2021/2025), Chapter 18 (Nonresidential Cooling and Heating Load) contains the gold mine: Table 9 & 10 , typically titled “Cooling Load Check Figures for Typical Commercial Buildings.”

But does that feel right?

Stop using 400 ft²/ton (which equals ~85 W/m²). That ignores windows, people, and latitude.