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1.5 Size names around the world

The same stone can be sold as 16–32, as 16/31.5, as US No. 4 or as "1¼ inch clean". This page lines the names up.

A size scale from 1 to 63 mm. The upper rows show the EN sizes used in this handbook. The lower rows show the nearest US size numbers, which start and stop at different sieves. 1 2 4 8 16 31.5 63 EN US 4–8 8–16 16–32 32–63 0–4 2–5 No. 8 No. 6 No. 4 No. 2 No. 57 sieve opening, mm
Each step on the scale doubles the opening. The sizes in this handbook stop at the EN sieves (1, 2, 4, 8, 16, 31.5, 63 mm). US sizes stop at inch sieves, so they overlap rather than line up.

At a glance

EN size
Two sieves in mm, smaller first: 16/31.5. This handbook writes it 16–32.
US size number
A grading band from ASTM D448, such as No. 57 for about 4.75–25 mm.
With fines
A size starting at 0, or gravel sold with its crushing fines left in. Compacts.
"Clean"
Washed to remove the fines. Clean rock will not compact tightly.

Why the names do not line up

EN, ISO

Sieves double at each step: 1, 2, 4, 8, 16, 31.5 and 63 mm, with optional sieves in between. A size names its two sieves.

US, ASTM

Sieves follow inch fractions above ¼ in and mesh numbers below it. A size number names a whole grading band, not two sieves.

Size names nearest match, not exact

This handbookENUS size number, mmInches
0–20/2–0–5⁄64 in
0–40/4Concrete sand (ASTM C33)0–5⁄32 in
2–52/5.6No. 9 (1.18–4.75)5⁄64–7⁄32 in
4–84/8No. 8 (2.36–9.5)5⁄32–5⁄16 in
8–168/16No. 6 (9.5–19)5⁄16–⅝ in
4–224/22.4No. 57 (4.75–25)5⁄32–⅞ in
16–3216/31.5No. 4 (19–37.5)⅝–1¼ in
32–6331.5/63No. 2 (37.5–63)1¼–2½ in
0–160/16–0–⅝ in
0–320/31.5–0–1¼ in
0–630/63–0–2½ in

Sieve openings same opening, two names

Opening, mmEN sieveUS sieve (ASTM E11)
0.063Yes, fines limitNo. 230
0.075–No. 200, US fines limit
0.125YesNo. 120
0.25YesNo. 60
0.5YesNo. 35
1YesNo. 18
2YesNo. 10
2.36–No. 8
4YesNo. 5
4.75–No. 4
5.6Set 1No. 3½
8Yes5⁄16 in
9.5–⅜ in
11.2Set 17⁄16 in
12.5Set 2½ in
16Yes⅝ in
19–¾ in
22.4Set 1⅞ in
25–1 in
31.5Yes, written 321¼ in
37.5–1½ in
63Yes2½ in

Step by step: translate a size you are given

  1. 1

    Find the largest grain in mm.

    That is what decides whether the material fits the layer. Use the tables above to turn inches or a size number into mm.

    The largest stone against a ruler
  2. 2

    Find the bottom of the size.

    "All-in" and a size starting at 0 mean fines are in. "Clean", "washed" and a size starting above 0 mean they are out. Other trade words vary, so ask.

    Stone with fines and clean stone side by side
    Stone with fines and clean stone side by side Illustration
  3. 3

    When it is close, ask for the grading sheet.

    A grading sheet lists the percentage passing each sieve. Compare it with the sizes in the tables above.

    A supplier's grading curve
Specifications

US size numbers

ASTM D448 lists standard sizes by number. Single numbers are narrow bands, such as No. 6 for 19–9.5 mm. Two-digit numbers are wider bands, such as No. 57 for 25–4.75 mm and No. 67 for 19–4.75 mm.

Upper size

In both systems a few grains may be larger than the upper size. EN 12620 allows up to 15 % over D for most stone. For US No. 57, 95–100 % passes the 25 mm sieve and all of it passes 37.5 mm.

Rounded labels

EN 12620 lets 31.5 mm be written 32, so 16/31.5 is sold as 16/32. This handbook writes 2/5.6 as 2–5 in the same way. Check the declared size on the delivery note.

Same sieves, two names

The US sieve table lists each opening in mm next to its US number, so a 2 mm EN sieve and a US No. 10 sieve are the same. The two systems pick different sieves from one series.

Sources

  1. ASTM D448-12 (copy published by the Government of Bermuda): size numbers No. 2, 4, 57, 6, 67, 8, 9 and their sieve limits
  2. FDOT Standard Specifications, Section 901: No. 57 grading, 100 % passing 1½ in, 95–100 % passing 1 in
  3. NIST Special Publication 960-1, Table 3.1: ASTM E11 sieve numbers and their openings in mm
  4. EN 12620:2002+A1:2008: basic sieve set plus set 1 or set 2, 31,5 (32), grading limits
  5. ASTM C33-03: fine aggregate for concrete, fines on the 75 µm sieve
  6. Washington State Department of Ecology: "clean" crushed rock is washed to remove fine material and will not tightly compact

US size numbers are the nearest match by sieve opening, not exact equivalents. Inches are a straight conversion of the mm sizes.

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