ROM Estimates vs Detailed Estimates: When to Use Each
Not every project requires the same level of estimating detail.
One of the most common mistakes owners and contractors make is requesting detailed estimates during conceptual phases or relying on rough budgets during procurement and execution.
Understanding the difference between ROM estimates and detailed estimates helps ensure the right information is available at the right time.
What Is a ROM Estimate?
A Rough Order of Magnitude (ROM) estimate is a high-level budget estimate developed when limited project information is available.
ROM estimates are typically used during:
- Conceptual design
- Feasibility studies
- Budget planning
- Early project development
ROM estimates often rely on:
- Historical cost data
- Benchmarking
- Conceptual quantities
- Industry cost trends
What Is a Detailed Estimate?
A detailed estimate is developed using completed drawings, specifications, and detailed quantity development.
Detailed estimates typically include:
- Takeoffs
- Quantity Surveys
- Labor calculations
- Equipment costs
- Material pricing
- Subcontractor pricing
When to Use a ROM
Use a ROM estimate when:
- Design is incomplete
- Budget approval is required
- Multiple options are being evaluated
- Quick decision-making is needed
When to Use a Detailed Estimate
Use a detailed estimate when:
- Bid submission is approaching
- Procurement decisions are required
- GMP validation is needed
- Construction execution planning begins
Final Thoughts
ROM estimates support planning.
Detailed estimates support execution.
Understanding the appropriate use of each improves decision-making, reduces risk, and increases project success.
At TBT Estimating Services, we provide both ROM and detailed estimating services, helping subcontractors and contractors make informed decisions throughout every phase of project development.