303 or 304? The honest answer depends on four things: the load the part carries, the environment it lives in, the tolerance the drawing calls for, and the volume you are buying. Below is the comparison we use when we quote both options.
If you already know which one you need, send the drawing and we will confirm it. If you are not sure, the table below usually settles it in one pass.
303 vs 304 Stainless: side-by-side comparison
| Dimension | 303 | 304 |
|---|---|---|
| Cost | Similar | Similar |
| Strength & performance | UTS 620 MPa | UTS 505 MPa |
| Corrosion / durability | Slightly lower — sulfur inclusions | Better general corrosion resistance |
| Machinability & tolerance | Free-machining, best of the austenitics | Work hardens, needs positive feeds |
| Lead time & tooling | 2-4 days | 3-5 days |
| Choose it when | The part is turned from bar and never welded | The part is welded or faces corrosive media |
How to decide
- Start with the failure mode, not the price. If the part fails from corrosion, 303 and 304 are not interchangeable no matter what the price difference is.
- Check the tolerance the function actually needs. Tightening tolerance on a material that machines poorly multiplies the cost difference.
- Check availability. A cheaper material with a four-week lead time is more expensive than a dearer one that ships in a week.
- Check the finishing route. Plating and anodizing behave differently on each option and can change the decision on their own.
Where the cost difference comes from
Material price is only part of it. Machining time, tool wear, scrap rate and finishing cost usually decide the final number. A material that costs twice as much but machines three times faster can be cheaper per part. That is why we quote both options with the process route shown, not just a single price.
Frequently asked questions
Is 303 better than 304?
Not in general. 303 wins when the part is turned from bar and never welded, and 304 wins when the part is welded or faces corrosive media. Give us the drawing and we will tell you which one we would choose and why.
How much more does 303 cost than 304?
The material cost difference is only one input. Machining time and tool life matter as much. Send the part and we will quote both options side by side so the comparison is real.
Can you machine both 303 and 304?
Yes. Both are routine for us, and we will say so if one of them is a poor fit for your geometry rather than quote it anyway.
Which one should I use for an export product?
Availability and documentation usually decide it. Both are widely stocked and certified, so the tie-breaker is normally the end user’s specification or the applicable standard.
Related pages
- Comparisons — the full index for this section.
- 4140 vs 1045 Steel for Shafts
- Inconel vs Titanium: Heat vs Weight
- 6061 vs 5052 Aluminum: Strength vs Formability
- Waterjet vs Laser Cutting for Thick Plate
- Instant CNC quote
- Tolerance quick reference
- Frequently asked questions
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