The Three Weights, and the Subtraction You Do Yourself

Any vehicle's weight story is told in three numbers:

• Unladen weight (also called kerb or service weight) — what the vehicle weighs empty: itself, ready to drive, no cargo and no passengers beyond the driver. A fixed property of the vehicle.
• Payload (maximum load) — the most weight it is designed and permitted to carry: cargo plus passengers plus fuel plus anything else added. The working capacity.
• Gross Vehicle Weight (GVW) — the maximum total the vehicle may weigh, fully loaded. The absolute ceiling.

They relate by one equation you never need to look up — and one rearrangement that is the whole practical point of this lesson:

GVW = unladen weight + payload
Payload = GVW − unladen weight

And both numbers are already on your logbook. The document that proves ownership also records the vehicle's tare/unladen weight and its Gross Vehicle Weight among the registered particulars. So your legal carrying capacity isn't something a seller tells you — it's a subtraction you do yourself, from figures you already hold.

Two habits follow:

• Know your own numbers. A driver who can't state their vehicle's GVW and payload is guessing at every load — and guessing high is how overloading happens without anyone deciding to overload.
• The logbook is the authority, not the seller or a sticker. "It'll handle a tonne easily" is a sales claim; the GVW on the logbook is the legal fact. Where they disagree, the logbook wins.

One number, two consequences: the GVW that sets your payload is the same figure that decides your licence category — Category B is defined by a GVW not exceeding 3,500 kg.