How many anchors do you need? A field rule of thumb

"How much hardware do I need?" is the first question every budget owner asks, and the honest answer — "it depends on your drawings" — isn't much help when you're trying to scope. So here's a rule of thumb that gets you close enough to budget with confidence, before the detailed placement plan.

Three numbers

Tags: one per asset or person you want to track. That one's easy.

Anchors: think roughly one per 100–200 m² of the area you want covered — that's the 10–15 m grid that gives sub-5 m accuracy — or, per room, about three to four anchors each. Dense metal, pillars or awkward shapes push that number up.

Gateways: at least one per level, building or separate structure (two per level if you want no single point of failure), and one gateway covers up to around 30,000 m².

So a simple 2,000 m² single-floor warehouse ballparks at roughly 10–20 anchors, one or two gateways, and a tag per tracked item. Enough to put a number on it.

The mistake to avoid: thinking in distance

It's tempting to ask "how far does one anchor reach?" and divide the floor by that number. Don't. An anchor isn't about distance — it's a reference point, and positioning works because several anchors each hear the same tag. What matters is the geometry: enough overlap that any point on the floor is seen by three or four anchors. That's why coverage is about placement and density, not range.

The same logic answers the vertical question. Height isn't resolved by a longer-range radio; it's resolved by putting anchors at the heights that matter, so the tag is heard by anchors above and below it. Placement is the lever, everywhere.

Where metal and open space change the maths

Steel reflects and absorbs 2.4 GHz signals, so metal-heavy sites need more anchors, mounted clear of large metal masses, with line of sight to the zones that matter. Large open areas go the other way: where you only need "roughly which area", a lighter BLE proximity layer covers more ground per device than a dense anchor grid. Right-size each area rather than blanketing everything.

Treat this as a budgeting estimate. The exact counts come from your drawings and a coverage check — the Coverage & Anchor Planning guide walks through the rules in more detail.