Handy workshop tools
Convert a measurement.
Find the wrench that fits.
Working from inches, or wondering which socket fits an M8 nut? Start here.
01 · Measurements
Imperial ↔ metric
Try 25.4, 25,4, 1/2 or 1 1/2. No thousands separators.
1 in = 25.4 mm
1 inch = exactly 25.4 mm. Results may be rounded. Fractional inches are rounded to the nearest 1/16 inch.
02 · Spanners & sockets
What fits this nut?
M8 → 13 mm spanner or socket
Both listed standards use this size. Check the tool sits snugly on the nut.
M8 means an 8 mm thread diameter. The wrench fits the outside flats: normally 13 mm on a regular M8 hex nut.
For other nut shapes, flange nuts, specialist fasteners or bolt heads, check their specification or measure across the flats. Allen keys fit an internal recess and use a different size.
03 · Floors, walls & boards
Convert an area
Enter the total area, not the length of one side. Decimals and fractions work here too; no thousands separators.
1 m² ≈ 10.7639 ft²
A rectangle’s area is length × width. A 3 m × 4 m floor is 12 m²—enter 12 above.
This converts area only. Material waste, overlaps and paint coverage are separate.
04 · Making a threaded hole
Drill before tapping
Choose the full thread marking on your cutting tap. The drilled hole is smaller than the finished thread.
M8 × 1.25 → 6.8 mm drill
Reference sizes for cutting taps, around 75% thread engagement. Confirm the drill size for your tap and material; manufacturer recommendations can differ.
No. 7 and Letter F are drill-bit sizes. They are markings to look for on the bit or drill index—not millimetres. The dimensions underneath describe that same bit, not a second recommended size.
What do the numbers mean?
M8 × 1.25 means an 8 mm thread with 1.25 mm between threads. 1/4-20 UNC means a 1/4-inch thread with 20 threads per inch. Match both numbers.
This is not a clearance-hole chart, wood-screw pilot chart or pipe-thread chart. Forming taps need different holes. For a blind hole, allow the extra depth specified for the tap and drill tip.
05 · Let a bolt pass through
Clearance holes
A clearance hole gives a bolt room to pass through a piece without cutting a thread into it.
Close fit leaves less room; free fit leaves more room for lining up parts. Metric medium fit sits between them. These are selected reference sizes, not wood-screw pilot holes or wall-anchor holes. Follow a project drawing when it specifies a hole size.
US numbered and lettered labels are drill-bit sizes. Converted dimensions describe the same hole, not a recommended substitute bit.
06 · Mark it out once
Even spacing
Space hooks or equal-width pieces evenly, with the same gap at both ends.
Use 0 for hook centres or drill marks. For slats, enter their actual width. Decimals and fractions such as 1 1/2 work too.
Show marking positions
Measure every position from the same left edge. Displayed measurements are rounded; the drawing is a layout aid.
| Item | Left edge | Centre |
|---|
Gap = (total width − all item widths) ÷ (number of items + 1). This plans the layout, not load-bearing or safety-critical spacing.
A quick reference
Regular metric hex nuts, measured across the flats. The differences are why thread size alone sometimes gives two answers.
Open the M4–M30 wrench-size table
| Thread | ISO 4032 | Older DIN 934 |
|---|---|---|
| M4 | 7 mm | 7 mm |
| M5 | 8 mm | 8 mm |
| M6 | 10 mm | 10 mm |
| M8 | 13 mm | 13 mm |
| M10 | 16 mm | 17 mm |
| M12 | 18 mm | 19 mm |
| M14 | 21 mm | 22 mm |
| M16 | 24 mm | 24 mm |
| M18 | 27 mm | 27 mm |
| M20 | 30 mm | 30 mm |
| M22 | 34 mm | 32 mm |
| M24 | 36 mm | 36 mm |
| M27 | 41 mm | 41 mm |
| M30 | 46 mm | 46 mm |
US finished hex-nut wrench sizes
| Thread diameter | Wrench opening |
|---|---|
| 1/4″ | 7/16″ |
| 5/16″ | 1/2″ |
| 3/8″ | 9/16″ |
| 7/16″ | 11/16″ |
| 1/2″ | 3/4″ |
| 9/16″ | 7/8″ |
| 5/8″ | 15/16″ |
| 3/4″ | 1 1/8″ |
| 7/8″ | 1 5/16″ |
| 1″ | 1 1/2″ |
Cutting-tap drill reference
| Full thread | Drill marking | Diameter |
|---|---|---|
| M3 × 0.5 | 2.5 mm | 2.5 mm · ≈ 0.09843 in |
| M4 × 0.7 | 3.3 mm | 3.3 mm · ≈ 0.12992 in |
| M5 × 0.8 | 4.2 mm | 4.2 mm · ≈ 0.16535 in |
| M6 × 1 | 5 mm | 5 mm · ≈ 0.19685 in |
| M8 × 1.25 | 6.8 mm | 6.8 mm · ≈ 0.26772 in |
| M8 × 1 | 7 mm | 7 mm · ≈ 0.27559 in |
| M10 × 1.5 | 8.5 mm | 8.5 mm · ≈ 0.33465 in |
| M10 × 1 | 9 mm | 9 mm · ≈ 0.35433 in |
| M12 × 1.75 | 10.25 mm | 10.25 mm · ≈ 0.40354 in |
| M16 × 2 | 14 mm | 14 mm · ≈ 0.55118 in |
| #4-40 UNC | No. 43 | 0.08900 in · 2.2606 mm |
| #6-32 UNC | No. 36 | 0.10650 in · 2.7051 mm |
| #8-32 UNC | No. 29 | 0.13600 in · 3.4544 mm |
| #10-24 UNC | No. 25 | 0.14950 in · 3.7973 mm |
| 1/4-20 UNC | No. 7 | 0.20100 in · 5.1054 mm |
| 5/16-18 UNC | Letter F | 0.25700 in · 6.5278 mm |
| 3/8-16 UNC | 5/16″ | 0.31250 in · 7.9375 mm |
| 1/2-13 UNC | 27/64″ | 0.42188 in · 10.7156 mm |
| #10-32 UNF | No. 21 | 0.15900 in · 4.0386 mm |
| 1/4-28 UNF | No. 3 | 0.21300 in · 5.4102 mm |
| 5/16-24 UNF | Letter I | 0.27200 in · 6.9088 mm |
| 3/8-24 UNF | Letter Q | 0.33200 in · 8.4328 mm |
| 1/2-20 UNF | 29/64″ | 0.45313 in · 11.5094 mm |