Magnet grade finder
Type in the magnet properties off your drawing — minimums, nominals, maximums, whatever it gives you — and every grade that cannot meet them grays out. What is left is what you can buy, and the finder names the cheapest coercivity class among them.
Everything runs in your browser. Nothing you type is sent anywhere — the page is served with a content security policy that forbids it from opening a connection at all. New to grade names? The five-minute guide to magnet grades explains the code.
Room-temperature values, as a drawing or datasheet gives them. Leave a box empty if the drawing does. A minimum or maximum is a hard limit; a nominal only has to fall inside the grade's band.
The grade map
For NdFeB, columns are coercivity classes and rows are energy classes. For samarium cobalt there is no shared class system worth the name, so the map lists the grades Arnold sells as Recoma and VAC sells as VACOMAX, under their own names, strongest first. Click any grade to see its numbers and exactly which limit it misses.
Sintered NdFeB
Samarium cobalt
Remanence against intrinsic coercivity
Each grade is drawn at its guaranteed HcJ, as a bar spanning its remanence: the published band for NdFeB, minimum to typical for samarium cobalt. Real magnets run to the right of their floor. Circles are NdFeB, squares Sm₂Co₁₇, diamonds SmCo₅. The shaded box is your Br and HcJ window.
Click a grade on either map for its numbers.
How it decides
Pass, maybe, fail
A grade passes when what its maker guarantees sits inside your limits. Where only the typical value or the top of a published band clears a limit, the grade gets the amber "maybe": some production would pass, and a supplier may be able to sort for it. Where even the typical value misses, it fails. A maximum is guaranteed only by a published maximum, and nobody publishes one for coercivity, so any maximum you put on coercivity is amber at best.
A nominal is not a limit. It only has to fall inside the grade's band, or between its minimum and typical value; if it doesn't, the grade turns amber.
Why that grade
Among the grades that pass, the finder prefers NdFeB to samarium cobalt, and Sm₂Co₁₇ to SmCo₅, which carries more samarium and cobalt per kilogram. Then it takes the lowest guaranteed coercivity, because in NdFeB every step up the letters is bought with dysprosium or terbium. Within that it takes the grade closest to your nominals, and failing that the lowest energy, which is the cheaper end of a class. It knows nothing about your temperature, your shape or your load line. If the part runs hot, the coercivity you need at room temperature is a decision for the field calculator, not this page.
Where the numbers come from
The NdFeB grades are the generic GB/T 13560 classes, with the numbers from HGT Advanced Magnets' public grade table: one maker's minimums, and other makers' differ by a few percent. The samarium cobalt grades are real catalog grades with their makers' own numbers: Arnold's RECOMA summary table, which gives a typical value and a minimum for every property and a maximum operating temperature, and Table 2 of VAC's VACODYM and VACOMAX brochure, which gives minimums for remanence and coercivity but only a typical energy product, and no temperature by grade. Both makers offer special grades beyond these on request. Treat a pass as a short list for the supplier conversation, not as the end of it.
Things no magnet can do
Some limits contradict each other, and the finder says so. Normal coercivity can never exceed intrinsic coercivity. In CGS units it can't exceed remanence either: HcB in kOe stays below Br in kG, because the recoil line is at least as steep as free space. And energy product can't exceed Br²/4 in MGOe with Br in kG. That last one is why an N52 tops out where it does.