Sieve Calibration (ISO 3310-1)

ISO 3310-1:2016 specifies the technical requirements for test sieves of metal wire cloth. For every nominal aperture size w, Table 2 (20 µm to 900 µm) and Table 1 (1 mm to 125 mm) publish three independent tolerances: +X, the maximum permissible error of any individual aperture; ±Y, the maximum permissible error of the average aperture; and σ₀, the maximum standard deviation of the aperture sizes.

X and Y are defined by the standard's own equations: X = (2·w^0.75/3 + 4·w^0.25) × 0.9 and Y = (w^0.98/27 + 1.6) × 0.9, with w in µm. This calculator's dataset transcribes both tables in full and is unit-tested against those equations, so every tolerance used in the verdict is traceable to the standard. For the 12 largest apertures (≥ 50 mm), the standard itself states that σ₀ "has no physical reality" given the small number of apertures to measure — that check is skipped for those sizes, and the verdict says so explicitly.

The market distinguishes three certification levels. Compliance relies on the manufacturer's conformity of the wire cloth to the table. Inspection and calibration certificates add a statistical statement about the mean aperture, at 99.0% and 99.73% confidence respectively, based on measuring a number of apertures on the actual sieve.

This tool computes the mean and sample standard deviation of your measured apertures and checks them against w ± Y, w + X and σ₀ (when applicable). For inspection and calibration levels it additionally requires the confidence interval of the mean (|mean − w| + K·s/√n, with K = 2.576 or 3.0) to stay within ±Y. The K-factor treatment is a documented approximation of ISO 3310-1 equations 4–7, which are not publicly available; the table checks themselves are exact.