What is 8mm in standard?

8 mm = 0.3150 in. The closest fractional ("standard") inch equivalents are 5/16 in (0.3125 in, 7.94 mm) — about 0.06 mm small — and 21/64 in (0.3281 in, 8.33 mm) — about 0.33 mm large. For sockets and wrenches, the 5/16 in size is the working substitute for 8 mm hardware in imperial-only tool sets.

What is 16 mm in standard?

16 mm = 0.6299 in. The closest fractional inch equivalents are 5/8 in (0.625 in, 15.875 mm) — about 0.13 mm small — and 41/64 in (0.6406 in, 16.27 mm) — about 0.27 mm large. For tools, 5/8 in is the standard substitute for a 16 mm socket; for thread/diameter work where tolerance matters, use the actual 16 mm tool.

What is 10 mm in standard?

10 mm = 0.3937 in. The closest fractional inch equivalents are 3/8 in (0.375 in, 9.525 mm) — about 0.5 mm small — and 13/32 in (0.40625 in, 10.319 mm) — about 0.32 mm large. For wrenching on M10 fasteners with US tools, 3/8 in is the common substitute; the slightly loose fit calls for steady torque to avoid rounding the head.

What volt is a standard outlet?

In North America, a standard residential outlet (NEMA 5-15R) supplies 120 V AC at 60 Hz with a 15 A breaker. The actual measured value sits in the ANSI C84.1 utilization band of 114–126 V (95 %–105 % of nominal). Heavier appliances use 240 V split-phase outlets like the NEMA 6-20 (20 A), 14-30 (dryer), or 14-50 (range / EV charger). In most of Europe, Asia, Africa and Australia the standard outlet is 230 V at 50 Hz.

What are standard PVC pipe sizes?

North American PVC schedule pipe runs in nominal sizes 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 4, 6, 8 inches with Schedule 40 (general use) or Schedule 80 (pressure / industrial) wall thickness. The "nominal" size is the inside diameter for ½–2 in pipes; for larger sizes it approximates ID under Schedule 40. ASTM D1785 governs the dimensions.

What is 8mm in standard?

8 mm = 0.3150 in. The closest fractional ("standard") inch equivalents are 5/16 in (0.3125 in, 7.94 mm) — about 0.06 mm small — and 21/64 in (0.3281 in, 8.33 mm) — about 0.33 mm large. For sockets and wrenches, the 5/16 in size is the working substitute for 8 mm hardware in imperial-only tool sets.

What is 16 mm in standard?

16 mm = 0.6299 in. The closest fractional inch equivalents are 5/8 in (0.625 in, 15.875 mm) — about 0.13 mm small — and 41/64 in (0.6406 in, 16.27 mm) — about 0.27 mm large. For tools, 5/8 in is the standard substitute for a 16 mm socket; for thread/diameter work where tolerance matters, use the actual 16 mm tool.

What is 10 mm in standard?

10 mm = 0.3937 in. The closest fractional inch equivalents are 3/8 in (0.375 in, 9.525 mm) — about 0.5 mm small — and 13/32 in (0.40625 in, 10.319 mm) — about 0.32 mm large. For wrenching on M10 fasteners with US tools, 3/8 in is the common substitute; the slightly loose fit calls for steady torque to avoid rounding the head.

What volt is a standard outlet?

In North America, a standard residential outlet (NEMA 5-15R) supplies 120 V AC at 60 Hz with a 15 A breaker. The actual measured value sits in the ANSI C84.1 utilization band of 114–126 V (95 %–105 % of nominal). Heavier appliances use 240 V split-phase outlets like the NEMA 6-20 (20 A), 14-30 (dryer), or 14-50 (range / EV charger). In most of Europe, Asia, Africa and Australia the standard outlet is 230 V at 50 Hz.

What are standard PVC pipe sizes?

North American PVC schedule pipe runs in nominal sizes 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 4, 6, 8 inches with Schedule 40 (general use) or Schedule 80 (pressure / industrial) wall thickness. The "nominal" size is the inside diameter for ½–2 in pipes; for larger sizes it approximates ID under Schedule 40. ASTM D1785 governs the dimensions.

Reference · Material specs

10 mm in Standard — Metric to Imperial Conversion Reference

The 10mm standard (fractional inch) socket equivalent is 13/32 in (0.4063 in) for an exact-fit match, or 3/8 in (0.375 in) for a slightly loose contractor substitute. This page tabulates 1–50 mm to inch conversions, lists the common substitutions for sockets and wrenches, and disambiguates the other "standard" meanings — standard outlet voltage, standard PVC sizes, standard rebar lengths. Reviewed by a licensed PE.

"Standard" — what people actually mean

In English-language search, "standard" carries multiple parallel meanings. For tool sizes (sockets, wrenches, drill bits) it almost always means fractional inch — the imperial system as opposed to metric millimetres. For an electrical outlet, "standard" means the receptacle every common North American household appliance plugs into: 120 V, 60 Hz, NEMA 5-15. For PVC pipe, rebar, or structural framing, "standard" references the published ASTM, AISC, or ACI dimensional spec.

The U.S. system of standardized fasteners and tool sizes traces back to William Sellers, the Philadelphia engineer whose 1864 paper introduced the 60° symmetrical thread profile that became the U.S. Standard (Sellers thread) — replacing dozens of incompatible shop-by-shop forms that preceded it.

Conversion formulas — mm to inch and back

Eq. 01 — Millimetres to inches SI

\text{in} = \frac{\text{mm}}{25.4}

·: in = Length in inches
·: mm = Length in millimetres
·: 25.4 = Exact conversion factor (1 in ≡ 25.4 mm)

Eq. 02 — Inches to millimetres SI

\text{mm} = \text{in} \times 25.4

·: mm = Length in millimetres
·: in = Length in inches

Eq. 03 — Closest fractional inch (1/64 resolution) SI

n = \text{round}\left(\frac{64 \cdot \text{mm}}{25.4}\right) \;\Rightarrow\; \frac{n}{64}\text{ in}

·: n = Closest 1/64 numerator
·: Round n down to lowest terms (e.g. 16/64 → 1/4) for the printed marking.

Reference values — mm to standard (fractional inch) chart

mm	Inches (decimal)	Closest fraction	Tool substitute
3	0.1181	1/8	1/8 in (3.18 mm)
4	0.1575	5/32	5/32 in (3.97 mm)
5	0.1969	13/64	3/16 in (4.76 mm)
6	0.2362	15/64	1/4 in (6.35 mm)
7	0.2756	9/32	9/32 in (7.14 mm)
8	0.3150	5/16	5/16 in (7.94 mm)
9	0.3543	23/64	11/32 in (8.73 mm)
10	0.3937	13/32	3/8 in (9.53 mm) loose
11	0.4331	7/16	7/16 in (11.11 mm)
12	0.4724	15/32	15/32 in (11.91 mm)
13	0.5118	33/64	1/2 in (12.70 mm)
14	0.5512	9/16	9/16 in (14.29 mm)
15	0.5906	19/32	19/32 in (15.08 mm)
16	0.6299	5/8	5/8 in (15.88 mm)
17	0.6693	43/64	11/16 in (17.46 mm)
18	0.7087	45/64	23/32 in (18.26 mm)
19	0.7480	3/4	3/4 in (19.05 mm)
20	0.7874	25/32	25/32 in (19.84 mm)
22	0.8661	7/8	7/8 in (22.23 mm)
24	0.9449	15/16	15/16 in (23.81 mm)
25	0.9843	63/64	1 in (25.40 mm)
27	1.0630	1-1/16	1-1/16 in (26.99 mm)
30	1.1811	1-3/16	1-3/16 in (30.16 mm)
32	1.2598	1-1/4	1-1/4 in (31.75 mm)
36	1.4173	1-7/16	1-7/16 in (36.51 mm)
50	1.9685	1-31/32	2 in (50.80 mm)

Engineering standards on this page

Document	Scope
NIST SP 811	Guide for the Use of the International System of Units (SI)
ASME B18.2.1 / B18.2.2	Hex bolts, nuts, head dimensions (US fractional)
ASME B18.2.3.1M	Metric hex bolts
ANSI C84.1	Standard system voltages, 120/240 V utilization band
NEMA WD 6	Wiring devices — receptacle and plug configurations
ASTM D1785	Schedule 40 / 80 PVC pipe dimensions
ASTM A615	Standard rebar grades and 60-ft stock length

Confirm the metric size Read the marking — 8 mm, 10 mm, 16 mm, etc. — printed on the side of the socket, wrench, drill bit, or fastener.
Convert millimetres to inches Divide by 25.4. Example: 10 mm / 25.4 = 0.3937 in. The "standard" (fractional inch) equivalent is the closest 1/64 fraction — 25/64 in for 10 mm.
Pick the closest fractional size For tools, you usually want the closest 1/16 or 1/32 in. 10 mm is between 3/8 in (9.525 mm) and 13/32 in (10.319 mm) — choose 13/32 if you need a snug fit on a metric fastener.
Account for tool tolerance A 13/32 socket on a 10 mm hex round-corners under high torque. For a true match, use the 10 mm metric tool. Imperial-only contractors typically carry 3/8 (≈9.5 mm) and substitute on M10 hardware after applying anti-rotation paste.
Mark the conversion in your shop binder Tape a 25.4-mm-per-inch chart inside the toolbox lid. The conversions never change, so a single laminated reference replaces dozens of mental approximations.

Worked example — choosing a wrench for an M10 hex bolt

An M10 hex bolt has a 10 mm shank and a 17 mm hex head. Convert: 17 mm / 25.4 = 0.6693 in. Closest fraction is 43/64 in (0.6719 in), but no socket is sold in 43/64 — common substitutes are 11/16 in (0.6875 in, 17.46 mm, ~0.5 mm large) or 21/32 in (0.6563 in, 16.67 mm, ~0.3 mm small). For torque application, the 21/32 fit is closer; the 11/16 is acceptable for loosening but should not be used to torque the bolt to specification — the slop will round the corners off the hex.

Comparison — metric vs. standard (US customary) tool sets

Aspect	Metric	Standard / SAE (fractional inch)
Step size	1 mm increments	1/16 in increments
Marking	Black numerals on chrome (10, 12, 14)	Stamped fractions (3/8, 7/16, 1/2)
Used for	Imported automotive, modern bicycles, electronics	U.S. plumbing, framing, agricultural, legacy automotive
Substitution risk	5/16 ≈ 8 mm — works under low torque	3/8 on M10 will round under high torque

Other "standard" references — voltage, cable, rebar, purlin

Standard outlet voltage and electrical standards

A standard North American outlet supplies 120 V AC at 60 Hz; the corresponding UK voltage standard is 230 V at 50 Hz. ANSI C84.1 sets the utilization band at 114–126 V (95 %–105 % of 120 V nominal). For 240 V split-phase appliances the standard receptacles include NEMA 6-20 (20 A), 14-30 (30 A dryer), and 14-50 (50 A range / EV charger).

Standard power cable

For residential 15 A 120 V branch circuits, the standard power cable is 14-2 NM-B with ground; for 20 A circuits 12-2 NM-B. Industrial standards rely on Type SO / SOOW flexible cord (UL 62) and TC-ER tray cable (UL 1277). Select the conductor count, gauge, jacket, and voltage rating before spec'ing — "standard power cable" alone is ambiguous.

Standard PVC sizes

ASTM D1785 sets the dimensions for Schedule 40 (general purpose) and Schedule 80 (industrial pressure) PVC pipe. Common stocked sizes — ½, ¾, 1, 1-¼, 1-½, 2, 3, 4, 6 in — match the brass and steel pipe dimensional series so that fittings interchange with metallic systems.

Rebar standard length and standard purlin spacing

Domestic rebar (ASTM A615 Grade 60) ships in 60 ft (18.3 m) stock lengths, with #4 (½ in), #5 (⅝ in), and #6 (¾ in) the most common slab and footing bars. For light-gauge metal building purlins (Z- and C-section), the typical purlin spacing under standing-seam roofing is 5 ft 0 in on-center, occasionally 4 ft for high-snow zones — verify against the manufacturer load tables and IBC 1604 dead/live combinations.

What is 8mm in standard?: 8 mm = 0.3150 in. The closest fractional ("standard") inch equivalents are 5/16 in (0.3125 in, 7.94 mm) — about 0.06 mm small — and 21/64 in (0.3281 in, 8.33 mm) — about 0.33 mm large. For sockets and wrenches, the 5/16 in size is the working substitute for 8 mm hardware in imperial-only tool sets.
What is 16 mm in standard?: 16 mm = 0.6299 in. The closest fractional inch equivalents are 5/8 in (0.625 in, 15.875 mm) — about 0.13 mm small — and 41/64 in (0.6406 in, 16.27 mm) — about 0.27 mm large. For tools, 5/8 in is the standard substitute for a 16 mm socket; for thread/diameter work where tolerance matters, use the actual 16 mm tool.
What is 10 mm in standard?: 10 mm = 0.3937 in. The closest fractional inch equivalents are 3/8 in (0.375 in, 9.525 mm) — about 0.5 mm small — and 13/32 in (0.40625 in, 10.319 mm) — about 0.32 mm large. For wrenching on M10 fasteners with US tools, 3/8 in is the common substitute; the slightly loose fit calls for steady torque to avoid rounding the head.
What volt is a standard outlet?: In North America, a standard residential outlet (NEMA 5-15R) supplies 120 V AC at 60 Hz with a 15 A breaker. The actual measured value sits in the ANSI C84.1 utilization band of 114–126 V (95 %–105 % of nominal). Heavier appliances use 240 V split-phase outlets like the NEMA 6-20 (20 A), 14-30 (dryer), or 14-50 (range / EV charger). In most of Europe, Asia, Africa and Australia the standard outlet is 230 V at 50 Hz.
What are standard PVC pipe sizes?: North American PVC schedule pipe runs in nominal sizes 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 4, 6, 8 inches with Schedule 40 (general use) or Schedule 80 (pressure / industrial) wall thickness. The "nominal" size is the inside diameter for ½–2 in pipes; for larger sizes it approximates ID under Schedule 40. ASTM D1785 governs the dimensions.

The U.S. inch is defined as exactly 25.4 millimetres. All conversions between U.S. customary length units and SI units are exact, derived from this relationship.

NIST SP 811 → Guide for the Use of the International System of Units (SI)

Sources

NIST SP 811 — Guide for the Use of the International System of Units (SI).
ANSI C84.1 — Electric Power Systems and Equipment Voltage Ratings.
ASME B18.2.1 / B18.2.2 — US hex bolt and nut dimensions.
ASME B18.2.3.1M — Metric hex bolts.
ASTM D1785 — PVC schedule pipe; ASTM A615 — Rebar.
NEMA WD 6 — Wiring device dimensional standard.