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AACE Cost Estimate Classes Explained (Class 1β5)
The AACE International cost estimation framework defines 5 distinct classes of estimates, ranging from Class 5 (early concept/feasibility with up to 100% variance) to Class 1 (detailed bidding with under 10% variance).
The Five Cost Estimate Classes
AACE International (formerly the Association for the Advancement of Cost Engineering) provides the standard terminology for estimators worldwide:
- Class 5: Concept Screening (0% to 2% design completion). Used for initial feasibility tests. Typical accuracy range is -50% to +100%.
- Class 4: Study or Feasibility (1% to 15% design completion). Used to secure preliminary financing. Accuracy ranges from -30% to +50%.
- Class 3: Budget Authorization (10% to 40% design completion). Anchors the official project budget. Accuracy ranges from -20% to +30%.
- Class 2: Control or Tender (30% to 70% design completion). Used for checking bids from contractors. Accuracy ranges from -15% to +20%.
- Class 1: Check Estimate (65% to 100% design completion). Detailed bid-grade document. Accuracy ranges from -10% to +15%.
Where ConstructionCostAI Fits In
Our AI estimator serves as a highly advanced Class 5 and Class 4 calculator. It enables project owners to skip weeks of early budgeting meetings by instantly generating structured estimates based on conceptual inputs. As design details solidify, you can override cost rates to move toward a Class 3 budget.