The two quotations do not describe the same object, which is why the lower number is not yet the better one. A pre-assembled cabinet arrives as a finished article; a flat-pack aquarium cabinet arrives as panels plus an assembly task you now own. For a single commercial order, pre-assembled normally lands cheaper, because the freight saving is smaller than the assembly, re-finishing and warranty burden it transfers to your site. Flat-pack wins in one case only: you fill containers, and you already run an assembly bench with incoming inspection. Stow volume decides which case you are in, not cabinet price.
Freight is charged on space, not on the cabinet
Carriers bill on whichever is greater, mass or volume, and once a cabinet set is light for the space it occupies, volume wins. An assembled cabinet is a rigid box, and its case adds clearance on six sides. Nested panels remove that air, so more units fit per container: roughly 33 cubic meters usable in a 20 ft unit, 67 in a 40 ft standard and 76 in a 40 ft high cube. The saving is therefore per container, not per unit; if your order does not fill one, the delta shrinks to two case sizes. Published shipping weights for cabinet-inclusive sets run from 120 kg to 500 kg.
What the two quotations leave out
A flat-pack quotation normally compares cabinet price ex-works against freight. The remaining blocks surface after the deposit is paid.
Table 1. Cost blocks that separate the two supply models
Two blocks are routinely underestimated. Re-finishing is not cosmetic: a door that no longer closes evenly against its frame is a warranty argument, not a touch-up, and the buyer owns it because the buyer assembled it. Delay never appears on an invoice, and the tank cannot be filled or tested until the cabinet is levelled beneath it.
Where the break-even sits for a 20 ft shipment
Worked example, assumptions stated. Freight and labour rates are planning assumptions, not published prices.
Table 2. Freight saving against assembly cost per unit
Assumptions: 12 percent stuffing loss; equal container fill; two technicians for 3.5 hours; no damage claim credit.
That break-even is the useful output: it converts a price argument into one number you can test against your own service team. Sensitivity runs one way: a 40 percent freight increase moves it only from 5.0 to 7.0 hours, while labour at USD 40 per hour moves it to 3.3 hours. Have your team assemble one set on a normal working day and count the hours.
Assembly is a site constraint before a labour cost
An assembled cabinet arrives at roughly 160 cm height on the published size lists, so door width, lift access and corridor bends decide whether it reaches the room. Flat-pack solves access, then moves the problem indoors: levelling, squaring and door alignment happen in a finished space subject to dust, floor protection and occupied hours. Sequencing matters too, because the cabinet must be levelled before the tank goes on it, and the filtration layout is normally fixed before the cabinet is closed up. Room-level requirements are covered in
Packing is a compliance line, not just a cost line
Panels shipping on pallets or in wooden crates are wood packaging material, which brings a phytosanitary rule into a freight question. Under ISPM 15, the FAO standard for wood packaging material in international trade, that wood must be heat treated to a defined schedule and marked with the IPPC stamp; untreated crating is rejected at destination. The cost falls on whoever holds the risk, which is contractual: under Incoterms 2020, FOB, CFR and CIF transfer risk once goods are on board, while CPT and CIP transfer it on handing to the carrier.
What to put in the RFQ
Settle that rule before agreeing a packing method, then specify packing per line item: stow volume per unit, crate outside dimensions, a container loading plan, who assembles and to what tolerance, the fixings and touch-up materials, warranty terms for a site-assembled cabinet, and MOQ plus lead time. Equalising specification before comparing price is the discipline used for supply scope in ; the site survey side is covered in .
Ruibit quotes packing method as a separate line item, so the freight delta can be read against the assembly hours it creates. For stow planning, the published specification of the states a 300 kg shipping weight across sizes L150/180/200 x W60 x H120 cm with the cabinet included, and the is the smaller reference point.
Send the set size and volume, destination city, assembly access, your labour rate and the container fill rate you expect. The number that decides it is already in this article: if your crew cannot assemble a set in under five labour hours, specify pre-assembled and stop negotiating the freight.
FAQs
1. At what order size does flat-pack start to pay?
Only when the shipment fills a container and you already run an assembly bench with incoming inspection. The saving is per container, not per unit: if the order does not fill one, the freight delta shrinks to two case sizes. The real test is labour, not volume. If your crew cannot assemble, inspect and re-finish a set in under five labour hours, pre-assembled wins even on a full container.
2. What should I ask for in a quote to compare the two models fairly?
Ask for stow volume per unit and case outside dimensions rather than cabinet dimensions, plus a container loading plan with the fill rate. Those figures convert freight into a cost per unit. Equalise supply scope at the same time: a flat-pack quote usually covers cabinet price ex-works and freight only, leaving machining, hardware and touch-up materials unclear.
3. Who carries the cost if a flat-pack cabinet is damaged during assembly?
The buyer, because the buyer assembled it. A door that no longer closes evenly against its frame is a warranty argument rather than a touch-up, so warranty terms for a site-assembled cabinet belong in the purchase order.
4. Does flat-pack avoid the wood packaging rules?
No, and it can increase exposure to them. Panels ship on pallets or in wooden crates, which is wood packaging material under ISPM 15, so it must be heat treated to a defined schedule and marked with the IPPC stamp. Untreated crating is rejected at destination, and that cost falls on whichever party holds the risk under the Incoterms 2020 rule you agreed.
