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The shear stiffness of granular material at small strain levels is a subject of both theoretical and practical interest. This paper poses two fundamental questions that appear to be interrelated: (a) whether this stiffness property is dependent on particle size; and (b) whether the effect of testing method exists in terms of laboratory measurements using resonant column (RC) and bender element (BE) tests. For three uniformly graded types of glass beads of different mean sizes (0·195 mm, 0·920 mm and 1·750 mm), laboratory tests were conducted at a range of confining stresses and void ratios, using an apparatus that incorporates both RC and BE functions and thus allows reliable and insightful comparisons. It is shown that the small-strain stiffness, determined by either the RC or BE tests, does not vary appreciably with particle size, and it may be practically assumed to be size independent. The laboratory experiments …