Why quotes differ 30% — and how to compare them.
The same drawing sent to five Chinese factories comes back with five different prices. Here is why that happens, and the five lines that make quotes comparable.
Short answer: when quotes differ by 30%, they are usually not pricing the same product. Each supplier fills the specification's gaps with its own assumptions — a cheaper material grade, a thinner gauge, an excluded finish, an ambiguous incoterm. The low quote is not cheap; it is answering an easier question.
Where the difference actually comes from
Specification gaps. "Aluminium window, white, 1.4mm" leaves dozens of decisions open: thermal break or not, which hardware brand, single or double glazing, what glass build-up, which gasket system. Each factory answers those gaps differently, and the price moves with every answer.
Material grade substitutions. 201 stainless instead of 304. A moisture-content shortcut on timber. Fillers in the board. None of this shows in a quotation line; all of it shows in year two.
Cost lines quietly excluded. Moulds, samples, packaging design, export cartons, loading labour, inland freight to the port, export customs paperwork. Every one is a real cost; whether it sits inside the unit price or ambushes you later is the difference between two "cheap" quotes.
Incoterms doing quiet work. FOB versus EXW versus CIF can be a 5–12% swing on the same goods — freight, insurance, local charges and documentation all move. Quotes on different terms are not comparable until they are restated on the same term.
The five-line comparison
To make quotes comparable, restate every quote on the same five lines:
| Line | Why it decides the comparison | Typical swing |
|---|---|---|
| 1. Written specification | Every supplier prices the same document, not their own assumptions | 10–25% |
| 2. Unit price at a stated quantity | Unit prices are volume-dependent | 5–20% |
| 3. One-time costs separated | Tooling and samples hidden in the unit price distort everything | 2–10% |
| 4. Trade term and named point | FOB / EXW / CIF are not the same product | 5–12% |
| 5. Price validity | A price that expires in a week is a different offer | 2–8% |
1. Specification, written. One document that both suppliers quote against — materials, grades, tolerances, finish, packaging. If a quote arrives without referencing it, send it again and ask for the number against that document.
2. Unit price at a named quantity, because unit prices are volume-dependent. Compare at the same quantity or not at all.
3. One-time costs separated — tooling, samples, test reports — and tooling ownership stated.
4. Trade term and named point — FOB which port, EXW which city — plus who books the freight.
5. Validity — how long the price holds, and what raw-material movement does to it.
Once every quote sits on those five lines, the differences that remain are real differences between factories — and a quote that stays competitive after being restated honestly is one worth pursuing.
Common questions
Should I just pick the cheapest quote?
+Not before the five lines are aligned. After they are, the cheapest quote on equal terms is often a genuinely efficient factory — but check why: newer machines, scale, or a thinner margin strategy are good reasons; a substituted material grade is not.
How many quotes should I collect?
+Three serious ones beat eight casual ones. A quote costs a factory real work; suppliers who know a tender is genuine quote more carefully. Send the same written specification to each, and compare on the five lines.
What if a supplier refuses to itemise?
+Itemisation is where negotiation happens, so some factories resist it as a matter of habit. Push once, politely, with a template. A factory that still refuses to separate one-time costs from unit price is telling you where the flexibility is — and where the audit trail won't be.
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一句话结论：报价差到 30%，通常说明它们标的不是同一个东西。每家供应商都在用「自己的假设」填补规格里的空白——更便宜的材料等级、更薄的壁厚、不含的表面处理、模糊的贸易条款。低价不是便宜，只是回答了一道更容易的题。
差价从哪来
规格空白。「铝合金窗、白色、1.4mm」留下几十个待定项：要不要断桥、什么品牌五金、单玻还是双玻、玻璃怎么配、用什么胶条系统。每家工厂对空白的回答不同，价格跟着每个回答动。
材料等级替换。201 不锈钢顶 304。木材含水率放水。板材里加填充料。这些都写不进报价单，但第二年都会显形。
悄悄不含的费用。开模、打样、包装设计、出口纸箱、装柜人工、内陆拖车、报关单证。每一项都是真实成本；它在单价里还是埋伏在后面，就是两份「便宜」报价的区别。
贸易条款做手脚。同一批货，FOB、EXW、CIF 能差 5–12%——运费、保险、港杂、单证全在动。条款不统一之前，报价不可比。
五行对比法
让每份报价都回到同样五条线上：
| 五条线 | 为什么它决定可比性 | 常见影响幅度 |
|---|---|---|
| 1. 书面规格 | 每家都在对着同一份文件报价，而不是各自假设 | 10–25% |
| 2. 指定数量下的单价 | 单价跟量走，不同数量不可比 | 5–20% |
| 3. 一次性费用单列 | 模具、打样混进单价会扭曲全部比较 | 2–10% |
| 4. 贸易条款与具名地点 | FOB / EXW / CIF 不是同一个商品 | 5–12% |
| 5. 报价有效期 | 一周就失效的价格，是另一个报价 | 2–8% |
1. 书面规格。一份双方共同对着报价的规格文件——材料、等级、公差、表面、包装。报价没对着它来，就把文件再发一次，要求按文件重新报。
2. 指定数量下的单价。单价跟量走，不同数量下的报价没法比。
3. 一次性费用单列——模具、样品、检测报告，并写明模具归谁。
4. 贸易条款加具名地点——FOB 哪个港、EXW 哪个城，运费谁订。
5. 有效期——价格保多久，原材料涨跌怎么处理。
五条线对齐之后，剩下的差价才是工厂之间的真实差距——诚实重述之后仍然有竞争力的报价，才值得追。
常见问题
是不是直接选最便宜的就行？
+五条线对齐之前不行。对齐之后，同条件下最便宜的报价常常确实是效率高的工厂——但要看原因：设备新、规模大、薄利策略，是好事；材料等级被换掉了，不是。
应该收集多少份报价？
+三份认真的比八份随意的有用。报价对工厂是真实的工作量；知道招标是真的，供应商才会认真报。把同一份书面规格发给每一家，按五条线对比。
供应商不肯拆开报价怎么办？
+拆分是谈判发生的环节，有些工厂出于习惯就是不愿意。礼貌地推一次，给个模板。推完还不肯把一次性费用和单价分开的工厂，等于在告诉您：灵活空间在哪，审计线索就不在哪。