How accurate is our construction cost estimate?
Our calculator shows a cost range and a reliability indicator per work package. This page explains how we derive confidence and how you can use it for planning.
How confidence is calculated
Confidence is based on data quality (e.g. known soil type vs unknown), stability of market rates for that work, and how much your inputs constrain the outcome. Each package gets a high, medium, or low label, and we aggregate into an overall confidence score weighted by cost.
Why estimates differ from final cost
Final costs differ from estimates because of material choices, contractor availability, site surprises, and market movement. The range and confidence indicators help you plan for that variation.
Market volatility
Construction markets can move with materials and labour. We use stable reference rates; confidence drops when inputs are incomplete or when a package is especially sensitive to local conditions.
Contingency reserve
For packages with low confidence, consider adding a contingency reserve. The overall confidence score gives you a single number to compare scenarios.
FAQ
Each work package is assigned high, medium, or low based on input completeness and rate stability. The overall score is a cost-weighted average expressed as a percentage.
Costs depend on materials, labour, site conditions, and market timing. Ranges and confidence levels reflect this uncertainty.
For items with low confidence or high impact, a contingency buffer is a common practice. Use the per-package indicators to decide where to add reserve.