H7 or H8? 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.
H7 vs H8 Fit: side-by-side comparison
| Dimension | H7 | H8 |
|---|---|---|
| Cost | Baseline precision bore | Slightly cheaper to produce |
| Strength & performance | Tighter location for bearings and dowels | Good for sliding fits and clearance |
| Corrosion / durability | No difference | No difference |
| Machinability & tolerance | Bore tolerance 0 to +0.025 mm at dia 50 | Bore tolerance 0 to +0.039 mm at dia 50 |
| Lead time & tooling | May need reaming or fine boring | Reaming is normally sufficient |
| Choose it when | The bore locates a bearing or a precision pin | The bore is a clearance or locating hole |
How to decide
- Start with the failure mode, not the price. If the part fails from corrosion, H7 and H8 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 H7 better than H8?
Not in general. H7 wins when the bore locates a bearing or a precision pin, and H8 wins when the bore is a clearance or locating hole. Give us the drawing and we will tell you which one we would choose and why.
How much more does H7 cost than H8?
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 H7 and H8?
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.
- T6 vs T6511 Aluminum Temper for Machining
- HDPE vs UHMW for Machined Parts
- Metric vs Imperial Threads for Export Parts
- Titanium Grade 5 vs Grade 2
- Instant CNC quote
- Tolerance quick reference
- Frequently asked questions
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