Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →M20 means a metric thread with a nominal diameter of 20 mm. The common coarse-thread version is M20 × 2.5, but fine pitches are available. For a typical ISO 4014 hex-head bolt, the reference dimensions are 30 mm across flats and 12.5 mm head height. M20 alone does not specify the bolt’s length, head form, material or strength class.
What does M20 mean?
The “M” identifies an ISO metric screw thread; “20” is its nominal diameter in millimetres. It describes the thread size, not the bolt’s head width or overall length. ISO 724:2023 specifies the basic dimensions of general-purpose metric screw threads according to ISO 261: ISO 724:2023.
A complete selection may also need the pitch, length, head style, fastener standard, material, finish and mechanical property class. Those details cannot be inferred from M20 alone.
What is the pitch of an M20 bolt?
Pitch is the distance between adjacent thread crests. The common coarse pitch for M20 is 2.5 mm, written M20 × 2.5. A reviewed M20 reference also lists fine pitches of 2.0 mm and 1.5 mm; the pitch should be confirmed from the drawing or mating thread rather than assumed (My Local Components, reviewed 16 August 2026).
#1 Best Overall
- Valued Carpenter Pencil Set: You will get 2 pcs solid carpenter pencils with 26 piece 2.8 mm refills, 1 replaceable sharpener, 1 plastic storage box.The complete carpenter pencils combination allows you to finish your work faster and more easily
- Deep Hole Marker Pencil: The deep-hole construction pencils adopts 45mm elongated tip design, which is more convenient to mark in the small hole or in other tight areas that other carpenter markers cannot reach
- Carpenter Pencils with Sharpener: The sharpener is screwed into the top of the work pencil, which won't get lost either. Built-in pencil sharpener that keep the lead with pointed and smooth to Improves line of sight in fine work
- Stronger Solid Lead: This work pencil is matched with a 2.8 mm thick lead , which is much thicker and stronger during the drawing process of construction work, it will not break or damage easily
- Marks on Various Surfaces: 3 colors solid construction pencil can marks on various surfaces,such as metal, plastic, wood, paper etc. Ideals for woodworkers, contractors, craftsmen, builders, merchants and masons
| Designation | Pitch | Practical implication |
|---|---|---|
| M20 × 2.5 | 2.5 mm | Common coarse-thread version. |
| M20 × 2.0 | 2.0 mm | Fine-pitch alternative; must match the mating thread. |
| M20 × 1.5 | 1.5 mm | Fine-pitch alternative; must match the mating thread. |
Bolts with the same nominal diameter but different pitches are not interchangeable. For a replacement, check an existing fastener or the specified thread before ordering or assembly.
What size spanner fits an M20 bolt?
For the cited M20 ISO 4014 hexagon-head bolt, the nominal width across flats is 30 mm, so a 30 mm spanner or socket is the reference fit. Its listed head height is 12.5 mm. These are head dimensions—not the M20 thread diameter—and other head styles take different tools (My Local Components, reviewed 16 August 2026; ISO 4014:2022).
Rank #2
- Ergonomically Designed: Work in tight areas with a compact design that gets into tough spots
- Compact and Lightweight: Both tools are designed to fit into difficult to reach spaces. The 1/4" impact driver has a length of 5.55 in. and weighs just 2.8 lbs, while the 1/2" drill/driver measures only 7.5 in. and weighs 3.6 lbs
- Both the DEWALT impact driver and electric drill driver feature integrated LED work lights with a convenient 20-second delay, ensuring enhanced visibility in dimly lit or challenging work areas
- One-Handed Loading - Keep one hand free with a 1/4 in. hex chuck that accepts 1 in. bit tips
- Power drill cordless with 1/2" single sleeve ratcheting chuck provides tight bit gripping strength, making bit changes faster and more secure
A socket-head cap screw is a different form: the same reference lists a 17 mm hex-key size for an M20 ISO 4762 example. Do not apply the 30 mm spanner dimension to socket-head fasteners.
M20 dimensions and workshop reference values
The following M20 values are listed by My Local Components in a guide reviewed 16 August 2026. They are reference dimensions and examples; confirm the applicable standard, drawing and design requirements for the actual job.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsRank #3
- 【Great Compatibility】This Katerk 1/4 inch hex shank bit holder is specifically designed for 1/4 inch hex shank drill bits. It's compatible with most 1/4 fast hex handles, hex sockets, various electric screwdrivers, and handheld screwdrivers. The bit holder makes it a valuable addition for any handyman.
- 【Secure and Safe】Built with a secure backup nut design, each drill bit holder securely locks onto your bits, ensuring they stay firmly in place. Additionally, our bit holder incorporates a high-quality steel ball rolling design that holds up to several kilograms of weight, ensuring your various drill bits don't fall off.
- 【Easy One-Handed Operation】The bit holder for impact driver allows you to change bits single-handedly, simplifying your workflow. Its multi-color design further allows for quick identification of the drill bit you need.
- 【Compact and Convenient】Thanks to its compact size, this 1/4 inch bit holder is easy to carry around. The bit holder allows for easy attachment to various tools, making this a convenient addition to your construction accessories. The Katerk bit holder is cast from high-quality alloy material, promising a long product lifespan. Despite its rugged strength, the bit holder remains lightweight, making it portable.
- 【Cool Christmas Gift For Men Stocking Stuffers】 This screwdriver bit holder, driver bit holder, impact bit holder, can be given as a gift to your loved one, especially for anyone involved in construction or electrical work. It's a must-have for stocking stuffers for men and women, tools gifts for dad, tech gadgets for men, gifts for dad, gifts for him, gifts for husband, gifts for boyfriend, cool gadgets for men, and cool gifts for dad.
| Feature | Reference value | Qualification |
|---|---|---|
| Nominal thread diameter | 20.0 mm | M20 designation. |
| Coarse pitch | 2.5 mm | Common coarse version. |
| Fine pitches | 2.0 mm; 1.5 mm | Alternatives; match the mating thread. |
| Hex-head width across flats | 30.0 mm | Cited M20 hex-head example. |
| Hex-head height | 12.5 mm | Cited M20 hex-head example. |
| Clearance-hole examples | 21 mm close; 22 mm medium; 24 mm coarse fit | Example fit values, not a substitute for the drawing or governing specification. |
| Tap-drill examples | 17.5 mm for M20 × 2.5; 18.0 mm and 18.5 mm for the listed fine-pitch alternatives | The 17.5 mm example assumes 75% thread engagement; confirm material, required engagement and tapping practice. |
ISO 4014:2022 covers steel and stainless-steel hexagon-head bolts with metric coarse-pitch threads from M1.6 to M64 in product grades A and B. ISO 4017:2022 covers corresponding coarse-thread hexagon-head screws, a separate product form. Their catalogue entries describe scope, not every dimension or tolerance; consult the full standard where controlled design, procurement or inspection requires it (ISO 4014:2022; ISO 4017:2022).
How to specify or choose an M20 fastener
- Match the thread. Confirm M20 diameter and the exact pitch—typically 2.5 mm for coarse thread, but fine pitches are also available.
- Choose the fastener form and standard. Specify hexagon-head bolt or screw as required, and whether the shank should be partly or fully threaded. ISO 4014 and ISO 4017 cover distinct product forms.
- Set the length and grip requirements. M20 does not give the fastener length. Use the drawing and joint details to choose a length that suits the parts being joined.
- Specify material, finish and property class. Select these for the application rather than assuming them from the thread designation.
- Check access and hole requirements. Confirm tool clearance, head form and the specified clearance hole; use the drawing or governing design requirements for drilling.
Why an M20 marking does not give a safe torque
Torque depends on more than thread diameter. The cited guide reports dry-condition examples of 405 Nm for property class 8.8 and 570 Nm for class 10.9 under its stated assumptions; these are not universal tightening recommendations (My Local Components, reviewed 16 August 2026).
Rank #4
- Long Nib and Deep Hole Marker: Our mechanical carpenter pencil with 45mm nib is designed for easy marking of deep holes or narrow areas. These construction pencils are the great choice for woodworking tools, construction tools, carpenter tools, contractor tools, wood carpentry tools and architect tools
- Extra Refills in 2 Colors for Versatile Marking: The construction mechanical pencil comes with 12 extra 2.8mm refills, including 6 red and 6 black refills. The black refill is suitable for light surfaces, while the red wax is perfect for dark surfaces. Our carpenter mechanical pencil makes sure that you'll have an ample supply for extended use
- Built-in Sharpener: Our construction pencil comes with a built-in sharpener to ensure the mechanical pencil tip is always sharp and ready for use. Never buy an extra pencil sharpener again. A great tool for any woodworker pencil, contractor pencils. The refill can easily be extended or retracted with a simple click of the pencils mechanical, allowing you to work more efficiently and accurately
- Portable Clip Design: Our deep hole construction pencil features a portable clip design, easy to carry and attach to your pocket or tool box, so that you can keep the carpenter pencils mechanical close at hand, making it a convenient tool to have on the go. Great gifts choice for carpenters
- Stronger Pencil Lead: The black refills are made of lead, sturdy and smooth. The red refills are made of wax, clear and light. These marking pencils are much thicker and stronger than normal pencils during the marking process of construction work, suitable for various surfaces, such as glasses, metal, boards, floors, walls, furniture, etc. The written marks can be easily wiped with a wet paper towel when needed
For an actual joint, follow its engineering specification and fastener-maker instructions. Friction changes with lubrication, coatings and surface condition, and the required preload depends on joint design. Do not transfer a generic dry-torque figure to lubricated hardware or a safety-critical connection.
Quick Recap
Best Value
- Milwaukee Ink all Fine Point Marker, Black, 4 Per Pack
- 4 per pack Features Clog Resistant Marker Tip Writes through Dusty, Wet and Oily Surfaces Durable Marker Tip for Writing on Concrete, OSB and Rough Surfaces
- Clog resistant tip writes on dusty, wet and oily surfaces and is optimized for rough surfaces such as OSB, cinderblock and concrete
- Hard hat clip- attaches for easy access
- Quick dry time with reduced smearing and marking
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
