Comparing subcontractor bids is one of the most critical tasks for quantity surveyors. A poor comparison can lead to cost overruns, delays, or selecting unreliable contractors. This guide covers proven methods for effective bid evaluation.
Why Bid Comparison Matters
The lowest bid isn't always the best bid. Effective comparison considers:
- Price accuracy — Is the bid realistic for the scope?
- Completeness — Are all items covered?
- Qualifications — Can this subcontractor deliver?
- Risk factors — What could go wrong?
- Value for money — Best overall package, not just cheapest
Rushing this analysis can cost far more than the time saved.
Preparing for Bid Comparison
Standardise Your Requirements
Before issuing tenders, ensure:
- Clear scope of work — No ambiguity in requirements
- Consistent Bill of Quantities — Same line items for all bidders
- Standard bid format — Template for pricing and qualifications
- Defined evaluation criteria — Published weightings if possible
Inconsistent requirements lead to incomparable bids.
Set Evaluation Criteria in Advance
Typical weightings might be:
| Criterion | Weight | Description |
|---|---|---|
| Price | 50% | Total bid value |
| Experience | 20% | Relevant project history |
| Programme | 15% | Proposed timeline and resources |
| Quality/Safety | 15% | Accreditations, methodology |
Adjust based on project priorities — fast-track projects might weight programme higher.
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The Bid Comparison Process
Step 1: Initial Compliance Check
Before detailed analysis, verify each bid:
- Received before deadline
- Complete documentation submitted
- Bid signed by authorised person
- All required attachments included
- No conditional or qualified pricing
Non-compliant bids may be excluded or require clarification.
Step 2: Arithmetic Check
Verify the mathematics in each bid:
- Check extensions (rate × quantity)
- Verify totals and subtotals
- Identify calculation errors
- Note any rate inconsistencies
Arithmetic errors should be corrected based on stated rates, not lump sum totals.
Step 3: Scope Alignment
Compare each bid against your requirements:
For each line item, check:
- Has the bidder priced it?
- Is the description consistent with your BoQ?
- Are any items excluded or qualified?
- What assumptions has the bidder made?
Create a matrix showing coverage across all bidders.
Step 4: Rate Analysis
Examine individual rates, not just totals:
Red flags to watch for:
- Significantly below-average rates on major items
- Front-loaded pricing (high preliminaries)
- Unusually low or high specific trades
- Round number pricing (suggests estimated, not calculated)
Below-market rates often indicate misunderstanding of scope or intention to claim extras.
Step 5: Exclusions and Qualifications
Every bid will have some qualifications. Common ones include:
- "Subject to site conditions"
- "Excludes weekend working"
- "Provisional quantities"
- "Access as described in tender"
Assess the cost impact of each qualification. What would it cost if these become issues?
Step 6: Normalize for Comparison
To compare fairly, adjust for:
- Scope differences — Add costs for excluded items
- Programme variations — Earlier completion may have value
- Risk allocation — Who bears contingency costs?
- Payment terms — Cash flow impact of different terms
Create an "adjusted comparison" that levels the playing field.
Common Bid Comparison Pitfalls
1. Focusing Only on Price
The cheapest bid often becomes the most expensive project. Consider:
- Past performance with similar work
- Financial stability of the company
- Capacity to deliver given current workload
- Quality of proposed team and methodology
2. Ignoring Qualifications
A bid with many exclusions may look cheap but carry hidden costs:
- "Builder's work by others" — Who pays for this?
- "Provisional rates" — What happens when finalised?
- "Excluded: overtime working" — Can they meet the programme?
3. Insufficient Clarification
Never assume what a bidder means. If unclear:
- Ask written questions
- Document responses
- Share clarifications with all bidders if appropriate
- Revise comparison based on answers
4. Bias Toward Familiar Names
New subcontractors may offer better value. Evaluate objectively using:
- Structured scoring matrices
- Reference checks for unfamiliar bidders
- Trial with smaller packages first
5. Time Pressure
Rushed analysis leads to mistakes. Allow adequate time for:
- Detailed review of each bid
- Clarification rounds
- Internal discussion
- Final evaluation and recommendation
Bid Comparison Tools
Traditional Approach
Many QS teams still use:
- Excel spreadsheets — Flexible but error-prone
- Paper bid summaries — Physical comparison documents
- Email chains — For clarifications and notes
This works but is slow and hard to standardise.
Modern E-Tendering
Digital platforms provide:
- Side-by-side comparison views — All bids on one screen
- Automatic calculations — No formula errors
- Structured clarification tracking — All Q&A documented
- Export to PDF/CSV — For presentations and records
The investment pays back in time savings and accuracy.
Presenting Your Recommendation
When presenting to project teams or clients:
Structure Your Report
- Executive summary — Recommended bidder and key reasons
- Process overview — How many invited, responded, timeline
- Evaluation methodology — Criteria and weightings used
- Comparison matrix — Side-by-side analysis
- Risk assessment — Key considerations for each bidder
- Recommendation — Clear decision with supporting rationale
Support Your Decision
Be prepared to explain:
- Why the recommended bidder, even if not cheapest
- How you assessed qualitative factors
- What clarifications were sought and received
- Risks associated with the recommendation
Post-Award Best Practices
After selecting your subcontractor:
- Debrief unsuccessful bidders — Maintain relationships for future tenders
- Document the process — For audit trails and lessons learned
- Archive all materials — Bids, clarifications, evaluation notes
- Monitor delivery — Does performance match the bid?
- Update your database — Note performance for future reference
Conclusion
Effective bid comparison is part science, part judgment. Structured processes and clear criteria protect against both bias and oversight. Invest the time upfront, and your projects will benefit from better subcontractor selections.
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