Metric Thread & Tap Drill
Reference Table
M1.6 to M48 — coarse pitch, fine pitch, tap drill Ø, clearance hole Ø, and thread engagement data. Search by thread size or drill diameter.
Drill Formula
Major Ø − Pitch
e.g. M8×1.25 → 8−1.25 = 6.8mm
Smallest standard metric thread. Used in miniature instruments and electronics. Tap drill: 1.25mm (#55 drill approx).
Small precision thread. Used in electronics, optical instruments, and model making. Tap drill: 1.6mm (#52 drill).
Common in electronics and small assemblies. Tap drill: 2.05mm (#46 drill approx).
Very common small thread. Used in electronics, brackets, and general hardware. Tap drill: 2.5mm (#39 drill). 75% thread engagement.
Common in consumer products and light machinery. Tap drill: 3.3mm (#30 drill). 75% thread engagement.
Widely used in automotive, electronics, and general engineering. Tap drill: 4.2mm (#19 drill). 75% thread engagement.
Most common metric thread. Used everywhere in machinery, automotive, and construction. Tap drill: 5.0mm (#9 drill or 5mm). 75% thread engagement.
Standard for medium-duty fastening. Used in furniture, machinery, automotive. Tap drill: 6.8mm (#H drill). 75% thread engagement.
Common structural and machinery thread. Tap drill: 8.5mm (Q drill). 75% thread engagement.
Heavy-duty fastening for structural and automotive applications. Tap drill: 10.2mm (#X drill or 10.2mm).
Used in automotive and heavy machinery. Tap drill: 12.0mm. Note: M14 is less common than M12/M16.
Major structural and machinery fastening. Tap drill: 14.0mm. Very common in construction equipment.
Heavy structural fastening. Used in construction, bridges, heavy machinery. Tap drill: 17.5mm.
Very heavy-duty fastening. Used in large structures and equipment. Tap drill: 21.0mm.
Extra heavy-duty. Used in heavy machinery, pressure vessels, and structural connections. Tap drill: 26.5mm.
Large structural fastening. Used in heavy construction and mining equipment. Tap drill: 32.0mm.
Very large fastening for heavy industrial applications. Tap drill: 37.5mm.
Largest commonly referenced metric coarse thread. Used in major structural connections. Tap drill: 43.0mm.
Fine pitch M8. Used where finer adjustment or better sealing needed. Common in hydraulic fittings and precision instruments.
Fine pitch M10. Used in automotive spark plugs, hydraulic fittings, and precision assemblies. Tap drill: 8.8mm.
Extra fine M10. Used in optical instruments and measuring equipment. Tap drill: 9.0mm.
Fine pitch M12. Common in hydraulic systems and automotive applications. Tap drill: 10.5mm.
Extra fine M12. Used in precision instruments and spark plug threads. Tap drill: 10.8mm.
Fine pitch M16. Very common in hydraulic fittings and automotive wheel studs. Tap drill: 14.5mm.
Fine pitch M20. Standard for hydraulic fittings and high-pressure connections. Tap drill: 18.5mm.
Medium fine M20. Used in heavy machinery where both strength and precision needed. Tap drill: 18.0mm.
Fine pitch M24. Used in heavy hydraulic systems and large precision assemblies. Tap drill: 22.0mm.
Fine pitch M30. Common in high-pressure hydraulic fittings and aerospace. Tap drill: 28.0mm.
Close fit clearance hole for M3 bolt. Used where precise alignment is required. ISO 273 fit: close.
Normal fit clearance hole for M3 bolt. Standard clearance for general applications. ISO 273 fit: medium.
Close fit clearance hole for M4 bolt. ISO 273 fit: close.
Normal fit clearance hole for M4 bolt. ISO 273 fit: medium.
Close fit clearance hole for M5 bolt. ISO 273 fit: close.
Normal fit clearance hole for M5 bolt. ISO 273 fit: medium.
Close fit clearance hole for M6 bolt. Used where alignment matters. ISO 273 fit: close.
Normal fit clearance hole for M6 bolt. Most common clearance for M6. ISO 273 fit: medium.
Close fit clearance hole for M8 bolt. ISO 273 fit: close.
Normal fit clearance hole for M8 bolt. ISO 273 fit: medium.
Close fit clearance hole for M10 bolt. ISO 273 fit: close.
Normal fit clearance hole for M10 bolt. ISO 273 fit: medium.
Close fit clearance hole for M12 bolt. ISO 273 fit: close.
Normal fit clearance hole for M12 bolt. ISO 273 fit: medium.
Close fit clearance hole for M16 bolt. ISO 273 fit: close.
Normal fit clearance hole for M16 bolt. ISO 273 fit: medium.
Close fit clearance hole for M20 bolt. ISO 273 fit: close.
Normal fit clearance hole for M20 bolt. ISO 273 fit: medium.
Standard internal thread tolerance for general applications. Used with 6g external thread for normal fits. ISO 965-1.
Standard external thread tolerance. Default for most commercial metric bolts. Provides 6μm plating allowance. ISO 965-1.
Tighter tolerance for precision applications. Used in aerospace and high-precision assemblies. ISO 965-1.
Wider tolerance for rough applications. Used in structural steel and general construction. ISO 965-1.
75% thread engagement is the standard for most tapping applications. Balances strength and ease of tapping. Higher % = stronger but harder to tap.
50% thread engagement is sufficient for most low-stress applications in soft materials. Easier to tap, less tap breakage. Not recommended for hard materials.
ISO Metric Thread Advanced Efficiency Guide
ISO Metric Thread Efficiency Optimization & Best Practices
Tap drill formula: Major Ø − Pitch
For metric threads, tap drill diameter = major diameter minus pitch. Example: M10×1.5 → 10 − 1.5 = 8.5mm. This gives approximately 75% thread engagement, which is the standard for most applications. For hard or brittle materials, use a slightly larger drill (lower engagement) to reduce tap breakage.
Coarse vs Fine pitch selection
Coarse pitch (M) is the default for general fastening — stronger, easier to assemble, and more tolerant of damage. Fine pitch (MF) is used for: (1) thin walls where full thread depth is limited, (2) adjustment/locking applications, (3) hydraulic/pressure fittings where sealing matters, and (4) vibration resistance (finer threads resist loosening better).
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Engineering Methodology & Design Standards: Metric Thread & Tap Drill Reference Table
Discipline: Fastener Engineering & Bolted Joint Mechanics
Governing Mathematical Formulation
In professional Fastener Engineering & Bolted Joint Mechanics workflows, accurate sizing and performance verification require consistent unit normalization and adherence to closed-form analytical mechanics. This Metric Thread & Tap Drill Reference Table utility implements the standardized engineering formulation:
Standardized parametric evaluation for Metric Thread & Tap Drill Reference TableComplete ISO metric thread table (M1.6–M48) with coarse/fine pitch, tap drill sizes, clearance holes, and thread engagement data. Every input change triggers an instant client-side recalculation across all coupled dependent variables, enabling rapid sensitivity analysis during preliminary and detailed CAD design phases.
Applicable Codes, Standards & CAD Integration
Ensure clearance hole diameters conform to ISO 273 / ASME B18.2.8 medium fit series and verify minimum thread engagement length (typically 1.0×d in steel, 2.0×d in aluminum) in your assembly BOM.
Engineering Verification Note: Analytical models assume homogeneous material behavior, steady-state boundary loading, and consistent dimensional units. Always apply appropriate service factors, corrosion allowances, or load and resistance factor design (LRFD / ASD) safety margins required by your governing code.
Frequently Asked Engineering Questions
Technical reference & verification guidelines for Metric Thread & Tap Drill Reference Table
What governing equation and methodology does the Metric Thread & Tap Drill Reference Table use?
The Metric Thread & Tap Drill Reference Table evaluates complete iso metric thread table (m1.6–m48) with coarse/fine pitch, tap drill sizes, clearance holes, and thread engagement data within the Fastener Engineering & Bolted Joint Mechanics domain using the governing formulation: Standardized parametric evaluation for Metric Thread & Tap Drill Reference Table. All intermediate quantities are computed in double-precision floating-point arithmetic to prevent cumulative rounding drift before final design verification.
Which international engineering standards apply to Metric Thread & Tap Drill Reference Table calculations?
Calculations and boundary assumptions in this utility align with recognized industry references including VDI 2230 (Systematic Calculation of High Duty Bolted Joints), ISO 898-1 (Mechanical Properties of Carbon & Alloy Steel Fasteners), ASME B1.1 / ISO 68-1. When preparing formal calculation packages or P.E. stamp submittals, always verify local jurisdictional code amendments and project-specific safety factors.
How should I integrate results from the Metric Thread & Tap Drill Reference Table into my CAD or BIM workflow?
Ensure clearance hole diameters conform to ISO 273 / ASME B18.2.8 medium fit series and verify minimum thread engagement length (typically 1.0×d in steel, 2.0×d in aluminum) in your assembly BOM. Using the baseline benchmark (standard nominal boundary parameters for Metric Thread & Tap Drill Reference Table), the solver yields verified design compliance metrics for Metric Thread & Tap Drill Reference Table, which can be directly cross-referenced against your parametric 3D assembly constraints, 2D fabrication drawings, or bill of materials (BOM).