Both methods are used. Raw grey and SG iron sand castings are often quoted per kilogram of finished casting weight, while small, complex, investment cast or machined parts are usually quoted per piece.
Neither method is better in itself. What matters is that you understand what the price includes, so you can compare quotes fairly and see what will change it later.
Per-kilogram pricing
A per-kilogram rate makes sense where cost follows weight: the metal, the melting energy and much of the moulding and fettling. It is common for simple, medium and heavy iron castings in standard grades.
Check which weight is used. It should be the finished casting weight after fettling, not the poured weight with risers and runners. Agree how weight is measured, and whether it is the drawing weight or the actual weight on delivery.
Per-kilogram rates hide complexity. A part with many cores, thin walls or high rejection costs the foundry more per kilogram than a simple block. Expect different rates for different parts even in the same grade.
Per-piece pricing
A per-piece price is usual when labour and process steps matter more than weight. That covers investment castings, small parts, machined parts, painted parts and anything with tight inspection requirements. It is also easier to compare with other processes, such as forging or machining from bar.
Per-piece prices still rest on weight and metal cost underneath. A good supplier will tell you the casting weight it assumed and how a metal price change would affect the piece price. Without that, you cannot check a later price revision.
What a full quote should show
- The material grade and standard, and the casting weight used for pricing.
- Pattern or tooling cost, shown separately, with ownership terms.
- Machining, painting and any assembly, each priced separately.
- Heat treatment, testing and certification, including any third-party inspection.
- Packing and the delivery term, such as ex works or FOB.
- Any metal price variation clause, and the index it follows.
- Quote validity and the quantity the price assumes.
Why prices move
Raw material is a large share of casting cost, so many foundries link their price to scrap, pig iron or alloy prices. This is covered in how scrap and pig iron prices affect casting costs. Energy, labour and the order quantity also play a part.
Delivery terms change the comparison as well. A per-kilogram rate ex works and a per-piece price FOB are not the same thing. See FOB, CIF or DAP for how the terms differ. A real price for your part comes only from quotes against your drawing and volumes.
Next step
We collect quotes on a common basis, break out tooling, machining and testing, and explain the differences. To compare foundries for your part, book a free sourcing review.