Metric Thread Pitch Chart: Coarse vs Fine Threads Explained

What Is Thread Pitch?

Thread pitch is the distance between two adjacent thread crests, measured in millimetres for metric threads. An M12 bolt with a 1.75 mm pitch means one full turn advances the bolt 1.75 mm. Every metric size has a default coarse pitch (what you get when nobody specifies otherwise) and one or more optional fine pitches — for example M12 coarse is 1.75 mm, while fine versions include 1.5 mm, 1.25 mm and 1.0 mm.

Nearly all standard stock fasteners — DIN 933 hex bolts, DIN 934 hex nuts, DIN 975 threaded rods — use coarse threads, because coarse is the default for 95% of applications.

Metric Thread Pitch Chart (Coarse & Fine)

Size	Coarse Pitch	Common Fine Pitches	Tap Drill (Coarse)
M4	0.70	0.50	3.30
M5	0.80	0.50	4.20
M6	1.00	0.75	5.00
M8	1.25	1.00 / 0.75	6.80
M10	1.50	1.25 / 1.00 / 0.75	8.50
M12	1.75	1.50 / 1.25 / 1.00	10.20
M14	2.00	1.50	12.00
M16	2.00	1.50	14.00
M20	2.50	2.00 / 1.50	17.50
M24	3.00	2.00	21.00
M30	3.50	3.00 / 2.00	26.50
M36	4.00	3.00	32.00

Thread designation examples: M10 = coarse (1.50); M10×1.25 = fine. If a drawing says just “M10”, it always means coarse.

Coarse vs Fine: When Each One Wins

Choose coarse threads when:

Speed of assembly matters — coarser threads install faster per turn
The bolt will be assembled and disassembled repeatedly (more tolerant of handling damage)
Threads may be slightly dirty, galvanized, or cut in the field
Lower-cost taps and dies; nearly universal availability

Choose fine threads when:

You need precise length adjustment (fine threads advance slower per turn)
Vibration resistance matters — finer helix angle resists self-loosening better
You want maximum tensile strength — the larger minor diameter gives a fine-thread bolt roughly 5–10% higher stress area
Wall thickness is limited and you need more thread engagement in thin material

Rules That Prevent Expensive Mistakes

Never mix pitches. An M12×1.25 nut spins freely onto an M12×1.75 bolt — and holds nothing. Always match the pitch, not just the diameter.
Fine threads strip more easily when cross-threaded — use the correct tap drill and start bolts by hand.
Fine-thread fasteners torque differently: for the same preload, fine threads need slightly lower torque. See our metric bolt torque chart for class 8.8/10.9/12.9 values.
Stainless fine threads gall more readily — apply an anti-seize compound; see our 304 vs 316 stainless guide for material pairing.

Frequently Asked Questions

How do I measure thread pitch without a gauge?

Use a ruler: count the thread crests over 10 mm (or 1 inch for imperial) and divide. For M10, about 6.5–7 crests per 10 mm = 1.5 mm pitch. A pitch gauge or a thread identification tool is faster and more reliable for production work.

Is a fine thread stronger than a coarse thread?

Slightly, yes. The larger minor diameter of a fine thread gives roughly 5–10% more tensile stress area, so a fine-thread bolt of the same size can carry a bit more load. But shear strength and fatigue behaviour depend far more on the bolt’s property class — see our strength grades 8.8/10.9/12.9 guide.

Are UNC and metric coarse threads interchangeable?

No. UNC is an imperial thread series (threads per inch); metric coarse is defined in millimetres. An M10 and a 3/8″ bolt are close in diameter but will cross-thread and fail if forced together.

Do you supply fine-thread bolts and rods?

Yes — standard stock is coarse pitch, while fine pitch (M8×1, M10×1.25, M12×1.5 etc.) is produced to order, including stainless threaded rods and custom machining. Send your spec through the enquiry form.