Guide
Cubic feet vs payload
A truck can run out of space or run out of legal/load capacity. DIY movers often check only length or volume—and discover the weight limit later.
Two different ceilings
Cargo volume (cu ft) estimates how much packed household volume fits inside the box. Payload (lb) is how much weight the chassis, tires, and GVWR allow. Whichever limit you hit first wins. A truck that looks “roomy” on volume can still be a poor choice if books, tools, or appliances push weight into the review or over band.
Length labels are a third, weaker signal. A longer exterior does not guarantee higher payload. Inside one brand, volume and payload can move in opposite directions—so treat every size as a pair of numbers, not a single ranking.
Examples from TruckSize vehicle data
- U-Haul 15′ lists 764 cu ft and 6,385 lb. U-Haul 20′ lists more volume (1,016 cu ft) but less payload (5,700 lb). Sizing up for furniture can reduce weight headroom.
- Penske 16′ lists 800 cu ft and 4,300 lb—close volume to U-Haul 15′, lower payload. Cross-brand “same length” shopping without checking weight is a common miss.
- Penske 22′ and 26′ both list 10,000 lb payload while volume jumps from 1,200 to 1,700 cu ft. Extra box space does not buy more rated weight on that step.
- Budget 26′ volume (~1,698 cu ft) competes with other 26′ trucks, but TruckSize keeps the conservative 9,180 lb payload after an on-page conflict with a higher marketing claim.
Where weight estimates come from
Items with published weight ranges use those independent low/high values. When an item has no independent weight range, TruckSize applies a constructive 7 lb/ft³ screen from household-goods planning practice, or a box density you choose (light / normal / books). That keeps weight visible without pretending every sofa has a lab-measured mass.
Medium or low weight confidence on the results screen is a planning signal: verify dense rooms (books, tools, full file cabinets) before you treat payload status as settled. The calculator still separates volume status from payload status so one green band does not hide the other risk.
Three failure modes that are not the same problem
Volume failure looks like “typical need” exceeding recommended/roomy capacity even when weight is fine. Payload failure looks like weight risk climbing while cubic feet still looks comfortable. Door-fit failure is independent of both: a piece can fit in the box and still not clear the rear opening. TruckSize treats unpublished rear-door dimensions as unknown—never as a green check—so you verify with the provider when door data is missing.
When two trips beat a bigger truck
If volume is only slightly over a mid-size truck but payload is already tight, a second trip can be safer than jumping to a long truck you barely need. If a full 3–4 bedroom inventory has no eligible single-truck result under recommended/roomy rules, the honest answer may be two trips, two trucks, or a professional assessment—not forcing a 26′ booking.
How results talk about risk
Volume status uses not-enough / tight / recommended / roomy. Payload status uses OK / review / high risk / over. Special-handling tags (heavy, fragile, oversize) surface as warnings without inventing door clearances. Print the results when you want a packing checklist without ads or navigation chrome.