How many subcontractors should you invite to bid?
The arithmetic for landing four to six real bids per trade, a per-scope target table, why over-inviting quietly loses you the subs you want, and when to go above or below the numbers.
"Invite everyone" sounds like a strategy. More invitations, more bids, lower number, what's not to like. In practice it produces fewer good bids, not more, and the arithmetic doesn't support it either. What follows is how to set a target per scope and what to do when the count comes up short.
Start from the bids you want, not the invitations
On a major trade you want four to six real, leveled bids. Fewer than three and you don't actually know the market price; you know what three firms felt like charging that week. More than six and you spend bid day leveling numbers you'll never use. On minor trades, two or three is plenty. On some specialties you'll be glad to get one at all.
So the real question is: how many do you need to invite to land five?
The conversion arithmetic
Assume a healthy response rate of 70 percent. Assume roughly 60 percent of the people who respond say "bidding," and about 85 percent of those actually deliver a number on the day. Then:
Invite 10, 7 respond, 4 say bidding, 3 or 4 bids arrive.
To land five bids at those rates you need to invite somewhere around 12 to 14. Now drop the response rate to 40 percent, which is where a lot of teams sit without knowing it, and the same target needs 22 to 25 invitations. This is why estimators with a weak process invite 40 and still end up with three bids. They're correct that they need more, but they're solving the wrong variable. The problem is the 40 percent, not the 40 invitations.
Why over-inviting costs you the bids you wanted
Good subcontractors talk to each other, and they can count. When a strong drywall contractor works out that you've invited thirty firms, their odds are worse than one in ten even if they bid well. A proper estimate on a $400,000 scope is two or three days of a senior estimator's time. At one-in-thirty odds the good ones pass, quietly, and the bidders you're left with are the ones who had nothing better to do that week.
Invite eight instead, and tell them so, and that same contractor sees a real chance and puts real effort in. Fewer bids. Better bids. And over time the good subs learn that your invitations are worth opening, which is worth more than any single job.
Ask any experienced sub-side estimator how they triage invitations. "How many others are on it" is in their top three questions, every time.
Targets per scope
These are for a mid-size commercial job with a healthy response rate. For reference, ConstructConnect's 2026 coverage guide treats three responsive bids per trade as the floor, and suggests commodity trades like electrical, painting, drywall and concrete can start with five or six invitations. Adjust for your own market and your own numbers.
| Scope | Bids wanted | Invite |
|---|---|---|
| Mechanical, electrical, plumbing | 4 to 5 | 6 to 10 |
| Drywall, concrete, structural steel | 4 to 5 | 6 to 10 |
| Roofing, glazing, masonry | 3 to 4 | 6 to 8 |
| Flooring, painting, tile, ceilings | 3 | 5 to 6 |
| Millwork, doors and hardware, specialties | 2 to 3 | 4 to 5 |
| Elevators, fire suppression, fire alarm | 2 to 3 | 3 to 5 (often the whole market) |
| Site work, landscaping, paving | 3 | 5 to 6 |
If those look low compared to what you do now, that's rather the point. If they look high, your list is thin in those trades, and the time to work on that is between bids, not in the middle of one.
When to go above the numbers
In a new market, invite wider on the first two jobs, note who performs, then narrow. In a hot market, "bidding" conversion drops; check counts on day 8 and add invitations then, to named firms. On an unusual scope, half your list will decline, so cast wider from the start. And on a trade where you've been burned, where the last three drywall bids came from the same two firms, add three new names and tell all of them there are six on it.
The common thread is that you invite more deliberately, for a reason, to specific firms. Not "select all."
When to go below
Negotiated or repeat work needs two or three bids for price validation and no more. Short bid periods: inviting fifteen doesn't create capacity, it creates fifteen emails. And small specialty markets: if three elevator companies will bid your job, inviting three is inviting everyone.
Check the count halfway through
Whatever you invited, the number that matters on day 8 is how many have said "bidding" per scope. Under three on a major trade means act now: widen the region, ask a trusted sub for a referral, phone the two firms you most want. The worst outcome isn't inviting too few. It's inviting the right number, not tracking the responses, and discovering on bid day that you have one mechanical price and no time to get another.
That per-scope count is the reason response tracking matters at all. Invite All shows it live per scope, something like "electrical: 4 bidding, 2 maybe, 3 silent." A spreadsheet with a status column and a pivot table gives you the same number with more effort. Either way, look at it on day 8. Day 20 is too late to do anything about it.
Aim for four to six bids on the trades that matter. Invite roughly double that from a clean list, personally, and tell them how many are on it. Fix the response rate before you widen the list. And check the count halfway.