Three bids for the same project can differ by 30% or more — and the lowest one is often not the cheapest. The difference is usually in what each contractor included, excluded or left as an allowance. Comparing bids properly is called bid leveling.
Step 1: Give every bidder the same package
Bids can only be compared if everyone priced the same thing. Send identical drawings, specifications, a written scope of work and a bid form that asks for prices in the same breakdown. Set one deadline and answer questions in writing to all bidders.
Step 2: Build a comparison sheet
List each scope item in rows and each bidder in columns. Enter what each bidder priced. Leave cells blank where a bidder didn't include an item — those blanks are the story.
Step 3: Hunt for exclusions and qualifications
Read every exclusion and assumption line. Common ones that turn into change orders:
- Permits and fees
- Site work, utilities and dumpsters
- Rock, unsuitable soil or dewatering
- Finish hardware, appliances and fixtures
- Temporary protection and cleaning
- Escalation clauses on materials
Step 4: Normalize allowances
An allowance is a placeholder amount for something not yet selected. A low allowance makes a bid look cheaper — until real selections arrive. Put every bidder on the same allowance amounts so you're comparing the work, not the guesses.
Step 5: Adjust to an apples-to-apples total
For each missing or excluded item, add a fair cost so every bid covers the same scope. The adjusted totals are what you should compare.
Step 6: Look beyond the price
- Schedule duration and start date
- Who is the actual project manager and superintendent
- Insurance, licensing and bonding
- References on similar projects
- Payment terms, retainage and change-order markup
Red flag: one bid far below the others. It usually means a scope gap, a mistake, or a plan to make the money back on change orders.
Step 7: Send clarifications before you choose
Ask each bidder to confirm or price the gaps you found. The answers often change the ranking.
Related: SiteLine bid leveling and estimating services · What does an owner's representative do?
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