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JIS Stainless Grade Converter
Type any designation you have. SUS304, 1.4301, S30400 or plain 304 all resolve to the same row. Twenty JIS stainless grades, with the machining consequence attached rather than left out.
Reviewed 2026-09-23 against JIS G 4303, EN 10088-3, ASTM A276, ISO 15510.
Equivalent is not identical.
Composition ranges overlap; certificates do not. A document written against EN 10088-3 will not satisfy an inspector told to expect JIS G 4303. Put the acceptable standards on the drawing. See the certificate guide.
| JIS | AISI / ASTM | EN no. | EN name | UNS | Family | Mach. | PREN |
|---|---|---|---|---|---|---|---|
| SUS301 | 301 | 1.4310 | X10CrNi18-8 | S30100 | Austenitic | - | 17 |
| SUS303 | 303 | 1.4305 | X8CrNiS18-9 | S30300 | Austenitic | 78 | 17Sulphide inclusions are pitting initiation sites, so real corrosion performance sits below what PREN suggests. |
| SUS304 | 304 | 1.4301 | X5CrNi18-10 | S30400 | Austenitic | 45 | 19 |
| SUS304L | 304L | 1.4307 | X2CrNi18-9 | S30403 | Austenitic | 45 | 19 |
| SUS305 | 305 | 1.4303 | X4CrNi18-12 | S30500 | Austenitic | - | 19 |
| SUS309S | 309S | 1.4833 | X12CrNi23-13 | S30908 | Austenitic | - | 23 |
| SUS310S | 310S | 1.4845 | X8CrNi25-21 | S31008 | Austenitic | - | 25 |
| SUS316 | 316 | 1.4401 | X5CrNiMo17-12-2 | S31600 | Austenitic | 36 | 25 |
| SUS316L | 316L | 1.4404 | X2CrNiMo17-12-2 | S31603 | Austenitic | 36 | 25 |
| SUS321 | 321 | 1.4541 | X6CrNiTi18-10 | S32100 | Austenitic | 36 | 19 |
| SUS347 | 347 | 1.4550 | X6CrNiNb18-10 | S34700 | Austenitic | - | 19 |
| SUS405 | 405 | 1.4002 | X6CrAl13 | S40500 | Ferritic | - | 13 |
| SUS410 | 410 | 1.4006 | X12Cr13 | S41000 | Martensitic | 54 | 12 |
| SUS420J1 | 420 | 1.4021 | X20Cr13 | S42000 | Martensitic | - | 13 |
| SUS420J2 | 420 | 1.4028 | X30Cr13 | - | Martensitic | 45 | 13 |
| SUS430 | 430 | 1.4016 | X6Cr17 | S43000 | Ferritic | 54 | 17 |
| SUS440C | 440C | 1.4125 | X105CrMo17 | S44004 | Martensitic | 40 | 17Much of the chromium is tied up in carbides, so usable corrosion resistance is well below the PREN figure. |
| SUS630 | 630 / 17-4 PH | 1.4542 | X5CrNiCuNb16-4 | S17400 | Precipitation hardening | 48 | 17 |
| SUS631 | 631 / 17-7 PH | 1.4568 | X7CrNiAl17-7 | S17700 | Precipitation hardening | - | 17 |
| SUS329J1 | - | 1.4460 | X3CrNiMoN27-5-2 | S32900 | Duplex | - | 33 |
Nothing matches that. Try the JIS number, the EN number or the UNS code.
How to read the two numbers
Machinability is a handbook index for annealed bar where 100 is AISI B1112 free-machining steel. Use it to compare grades against each other, never to set a cycle time. It is blank where there is no defensible published figure.
PREN is the pitting resistance equivalent, chromium plus 3.3 times molybdenum plus 16 times nitrogen, calculated from typical mid-range chemistry. Two grades carry a caveat in the table because the number overstates how they behave: SUS303, where sulphide inclusions are themselves corrosion initiation sites, and SUS440C, where much of the chromium is locked into carbides rather than available at the surface.
Where the mapping breaks down
SUS420J1 and SUS420J2 both map to AISI 420, and they are not the same material: roughly 0.16 to 0.25 per cent carbon against 0.26 to 0.40 per cent, which is the difference between about 50 HRC and about 55 HRC. Duplex has no AISI numbering at all, so SUS329J1 is quoted against UNS or EN. Ferritic equivalence is looser than austenitic across every standard.
The full explanation is in the equivalents guide.
Disagrees with the standard in front of you? Write to sales at suscnc.com with the clause and we will correct it and say so.