How to size a target region before scouting supplier diversification sites

Most dual-source projects fail at the scoping stage, not the site visit. Someone draws a circle on a map, usually a clean 200 km or "same province," and the team spends the next month screening sites that were never going to clear freight cost or weren't built for the right process in the first place. The radius decision happens before anyone books a flight, and it's the one step that rarely gets written down anywhere.

Start from the constraint that bites first

Your reference supplier already tells you most of what the region needs to look like. If the plant runs heat-treat or a wet process, matching utility access matters as much as matching floor space, sometimes more. If product moves by container to a coastal DC, a candidate four hours inland on a single highway corridor carries a different cost structure even if the building itself is a dead ringer.

The radius defines the area where three things hold at once: the logistics lane to your existing customers stays workable, the labor and utility costs stay inside your landed-cost model, and the plant typology, scale and layout look like something that could run the same product. Draw the circle around the second constraint first, then check it against the other two. Teams that draw it around the first thing they think of, usually "within the same country," end up with a shortlist that's geographically neat and operationally useless.

A rough starting point: if your reference supplier sits in a dense industrial cluster (parts of the Pearl River Delta, northern Vietnam, the Guadalajara corridor), a 100-150 km radius usually holds enough site density to find real candidates without dragging in a different labor market. If the reference plant is a standalone operation in a less built-up region, you'll need to widen past 300 km just to get enough candidates to compare, and at that point the freight-lane check matters more than the raw distance.

Why a radius that's too wide costs you more than one that's too narrow

A wide radius feels safer. It isn't. Every extra 50 km you add roughly doubles the number of industrial sites your team has to eyeball, and most of that growth is noise: warehouses, assembly sheds, and plants built for a completely different process that happen to sit in an industrial zone. If your team is screening from a directory listing or walking a trade-fair floor, that noise is exactly what eats the weeks. You end up shortlisting three sites that looked fine on paper and turn out, on the ground, to have a completely different roof structure or no rail spur.

Sharpening the filter inside the circle fixes more than shrinking the circle does. Define the plant type and scale band first (square footage, number of bays, dock count if you know it), then let the region be as wide as it needs to be to find three or four sites that fit that profile. A wider region with a tight filter beats a tight region with no filter.

What to check once you have a radius

Before sending anyone to scout, pressure-test the circle against freight data you already have: lane rates from the reference plant's region to your main customers, and whether the candidate region crosses a border or port that changes duty treatment. Then check labor: a region two hours from the reference supplier can sit in a completely different wage band if it crosses a provincial or state line. Neither of these kills a candidate by itself, but either one changes how you weight the shortlist once sites come back from scouting.

This is also where it helps to see the reference site and candidates side by side rather than imagining the match from a floor-plan PDF or a supplier's own photos. Sourcing Candidate Search builds exactly that: a ranked shortlist of sites in your target region that physically resemble the plant you're already sourcing from, same type, similar scale, comparable access, shown next to the reference site so you're not guessing at fit before anyone drives out.

Get the radius right and the rest of the scouting trip gets shorter. Get it wrong and you'll spend the trip finding that out the hard way.

If you've already got a reference supplier and a rough region in mind, that's the starting point for a Sourcing Candidate Search shortlist.