M24 Spring Washer Dimensions: 24.3–25.3 mm Inner, 40 mm Outer

Every value is taken from GB/T 93-2025 Fasteners — Single coil spring lock washers — Normal type, Table 1 (PDF pages 8–9 = text pages 2–3), in millimetres. d = inner diameter; S(b) = the section dimension column of Table 1, quoted here exactly as the standard writes it, with no symbol conversion (GB/T 859-2025, the light series, splits S and b into separate columns — the two standards have different dimension tables and cannot be cited interchangeably); H = free height; m ≤ = the upper limit of m in Table 1. Sizes in parentheses ((14) / (18) / (22) / (27) / (33) / (39) / (45)) are the non-preferred sizes listed in the standard's table note.

The bracketed sizes ((14) / (18) / (22) / (27) / (33) / (39) / (45)) are non-preferred; size 1.6 is new in this 2025 edition, and this edition also changed some d dimensions.

Clickable sizes in the first column are the 10 sizes we quote (M3 / M4 / M5 / M6 / M8 / M10 / M12 / M16 / M20 / M24) — open one to see its outer diameter and unit weight. For every other size this page gives the standard dimensions only and no weight: without a weight coefficient we do not invent a figure.

Outer diameter D and thickness coefficient t come from the product catalogue weight coefficients (spec_json.weightCalc: method = washer_formula, version = v2, formula = ring_area*thickness); the unit weight is recomputed with the identical parameters and formula π/4·(D²−d²)·t·ρ, with d at the nominal diameter and ρ = 7.85 g/cm³ for carbon steel (304 / 316L follow the density table below). The figures are the catalogue's rounded_g basis (1 decimal below 1 g, whole grams at 1 g and above) — the same numbers used on the product pages and in quotations.

Edition difference: our catalogue coefficients vs GB/T 93-2025 Table 1 (size by size)

GB/T 93-2025 has replaced GB/T 93—1987 (issued 2025-10-31, effective 2026-02-01) and its Table 1 does not include an outer diameter column. Below, the catalogue coefficients (outer diameter D × thickness coefficient t) sit next to the matching Table 1 columns: thickness difference = our t − Table 1 S(b) nominal; weight difference = our ring area uses the nominal bore (12 mm for M12) while Table 1 gives the inner diameter as a range (12.2–12.7 mm for M12) — a smaller bore makes the ring area larger, so our unit weight runs above a Table 1 inner-diameter basis; the spread is computed at both ends of the range (d min / d max). The table only describes the relation between the two bases: nothing is changed in the catalogue, and our coefficients are never presented as Table 1 values.

How to use it: quotations, freight and packing go by the catalogue basis (estimate, not an inspection figure); dimensional verification against GB/T 93-2025 Table 1 goes by the first table above. The gap between the two is exactly what this table lists, size by size — no manual back-calculation needed.

Material density conversion

Three material options are quoted (carbon steel / 304 / 316L): the unit weights above are on the carbon steel basis, and other materials scale by the density ratio (weight × factor). GB/T 93-2025 groups materials in Table 2 as spring steel / stainless steel / phosphor bronze, and that table is identical in GB/T 859-2025 — it cannot tell the normal type from the light type; the only dividing lines are Table 1 dimensions and the range limit.

Anti-loosening limits: washer spread with 10.9 / 12.9 property classes

GB/T 93-2025 carries this note in its scope (PDF page 7 = text page 1): where the spring lock washers specified in this document are used with bolts and screws of property classes 10.9 and 12.9, attention should be paid to the washer spreading (opening-up) phenomenon.

That is a caution stated by the standard, not a prohibition for classes 10.9 / 12.9 — spring washers can still be used, but a high-strength joint carries high preload and the washer may open up radially, changing the fit and the clamping state. In practice: (1) check bolt torque against the target preload (our torque chart for the same size gives ranges by the K-factor method); (2) where the spreading risk is high, use or add another locking method (all-metal prevailing torque nuts, threadlocker, double nuts, other elastic washers), chosen by the designer from the joint load and vibration duty; (3) surface defects follow Table 2 — cracks, rust and harmful dents, scratches and burrs are not permitted. We publish no spring or clamping force figures: GB/T 93-2025 gives none, so any force derived from dimensions or grade would not be a standard value.

Data basis and assumptions

Two kinds of figures, two sources, marked column by column. (1) The standard dimension columns (d / S(b) / H / m) are taken value by value from GB/T 93-2025 Table 1 (PDF pages 8–9) and carried in utils/springWasherCalc.ts; the check script ops/tools/gen-spring-washer-chart-data.mjs --check re-parses the distilled fact layer and compares every cell (9 columns × 24 sizes, all equal). (2) The weight column and the 10 outer diameter / thickness coefficients come from the product catalogue, MySQL prd_sku.spec_json.weightCalc (method = washer_formula, version = v2, formula = ring_area*thickness, confidence = estimate): the recomputed raw_g and rounded_g match all 53 SW- SKUs in the catalogue exactly. This page copies nothing beyond those standard table values and does not use the dimension table of GB/T 859 (light type).

Limits: (1) the dimensions here are standard table values, not a measurement of the parts in your hands — cite them as "per GB/T 93-2025 Table 1, size N has d …, S(b) nominal …, H …, m ≤ …" and never as our measured product data; (2) the weights are quotation estimates (quoting, freight, packing), while real unit weight varies with chamfers, the split shape and coating (hot-dip galvanising about +4.5%) — settle on actual weighing; (3) our weights use the nominal bore, and the gap versus the Table 1 inner-diameter range is listed in the edition-difference table, so no manual correction is needed; (4) sizes we do not quote (1.6 / 2 / 2.5 / 14 / 18 / 22 / 27 / 30 / 33 / 36 / 39 / 42 / 45 / 48) carry standard dimensions only and no weight — no coefficient, no figure; ask for a quote by standard and size; (5) this page publishes no spring force, clamping force or test load figures — GB/T 93-2025 gives none, and elasticity, torsion and hydrogen embrittlement resistance are referenced to GB/T 94.1.