How many subcontractors should I invite to tender?

The right number balances two opposing risks, and it is smaller than instinct suggests. Too few, and you have no real competition and no benchmark for whether a price is fair; a package let to a single quotation is a negotiation, not a tender. Too many, and each invitee knows their odds are poor, so the good subcontractors decline to spend a day pricing a job they probably will not win, and you are left with returns from whoever was quiet that week rather than whoever is best. Three or four capable tenderers is the usual sweet spot: enough for a spread and a benchmark, few enough that each treats the enquiry as worth a serious price. Quality matters more than quantity, so vet the list, invite subcontractors who can genuinely do the work to the programme, and confirm they intend to price it before the enquiry goes out, because a list of six that yields two real returns is worse than a list of three that all price properly. Give them enough time, since a rushed tender comes back hedged with qualifications, and keep the list consistent so you compare the market rather than a random sample of it. The aim is not the widest net; it is the smallest number of serious tenderers that still gives you a competitive, comparable set of returns.

Take a contractor who, wanting to be seen to test the market, sends a mechanical package to eight subcontractors. Three decline immediately, two never respond, and of the three returns that arrive, two are hurried and heavily qualified because those firms rated their chances at one in eight and priced accordingly. The contractor chooses between two thin tenders and one considered one, a worse position than a smaller enquiry would have produced. On the next package the buyer prequalifies, calls four firms to confirm they will price it, and sends the enquiry to those four with a fair period to respond. All four return considered, comparable prices, the levelling is straightforward, and the winner comes from genuine competition rather than whoever happened to bother. Fewer invitations, better tenders, a cleaner decision.