Definition
The base bid is the price a subcontractor quotes for the core, fully-defined scope of work in your package — the work the drawings and specifications describe without optional add-ons or contingencies. It is the number you compare against every other bidder, because it is supposed to cover the same defined SOW for each of them. What sits outside the base bid is priced and evaluated separately: alternates (optional scope you may or may not accept), allowances (placeholder dollars for items not yet fully designed), and unit-price adjustments (changes to estimated quantities settled later at agreed rates).
For a heavy-civil general contractor reviewing the 5 to 15 bids it receives on a package, the base bid is the apples-to-apples anchor. Mixing alternate pricing or allowance dollars into the comparison rewards whichever sub structured its proposal most favorably rather than whoever offered the best price for the defined work.
A worked example
You receive three bids on a drainage package. Sub A submits a base bid of $1,200,000. Sub B comes in at a base bid of $1,175,000, but its proposal folds in a $60,000 allowance for unsuitable-material disposal that Sub A carried separately. Sub C quotes a $1,210,000 base bid plus an $80,000 alternate for an upgraded outfall structure. To compare correctly, you isolate each base bid for the defined scope: $1,200,000, $1,115,000 once Sub B's allowance is pulled out, and $1,210,000. The alternates and allowances are then evaluated on their own merits — not blended into the base-bid ranking.
Why it matters when you evaluate sub bids
Award decisions stand or fall on a clean base-bid comparison. If one sub's cover-sheet total quietly includes an allowance and another's does not, the raw numbers measure different things and your ranking is wrong before scoring even starts. Pulling alternates and allowances out of the base bid is what lets you level the field, score price against a like-for-like figure, and defend the selection to an owner. It also keeps later money — accepted alternates, drawn-down allowances, quantity adjustments — on a separate ledger you can track instead of burying it inside one headline price.
How Bid Reasoner handles it
For bids submitted through the bidder portal, Bid Reasoner records the sub's base bid separately from its stated alternates, and the price score is calculated from that base bid plus your leveling adjustments; for other bids it uses the total read from the bid. Price is scored alongside scope, schedule, compliance, performance, and risk. Two-way scope-coverage gap analysis checks each base bid against your SOW by pay-item code and lists anything missing; scope findings the AI saves cite the document and page. The four deterministic pricing rules then run on every bid that has been read: unbalanced unit prices at or under $1.00, peer outliers at 2x or more or 0.5x or less of the pay item's median (3+ bids), total-bid outliers 20% or more off the median total (3+ bids), and front-loaded mobilization at 10% or more of total. The result is a base-bid ranking you can rank, override on the record, and export into the generated award documents.