Plug number
A plug number is a placeholder figure an estimator carries for a scope with no bid yet, so the overall estimate stays complete.
Also written as plug, plugged number, carried number.
Last updated
Reviewed by Eric Collin · President and Founder of Firmo Construction, 20+ years in preconstruction and bid evaluation
Bids do not all arrive, and some trades attract no coverage at all. Rather than leave a line at zero — which quietly understates the project — the estimator carries a number from historical cost, a supplier budget, or judgment.
A plug is the estimator's own placeholder, which is what separates it from an allowance: an allowance is a sum inside a bidder's price with a contractual reconciliation behind it, while a plug has no bidder and no contract at all.
The discipline that matters is tracking them. A plug is a known unknown while it is flagged as one, and becomes a budget hole the moment it is forgotten and starts being read as a real price. They surface at buyout, when the plug meets an actual subcontract, and the gap between the two is nobody's error but everybody's problem.
In a comparison, a plug is not a bid and should never sit in a column as though it were one.
- Allowance
An allowance is a fixed sum carried in a bid for work that is not yet defined well enough to price, to be reconciled against the actual cost later.
- Buyout
Buyout is the process, after a project is won, of converting each estimated scope into a signed subcontract at an agreed price.
- Bid leveling
Bid leveling is the process of adjusting subcontractor bids onto a common scope so their prices can be compared like for like.
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