Weight Plates (Iron & Bumper)

Weight plates load the sleeves of a barbell or the pegs of plate-loaded machines.

Hole size: Olympic plates have a 50 mm (2 in) center hole to fit Olympic bar sleeves; standard plates have a ~1 in hole. They are not interchangeable.

Iron / steel plates. Dense and compact; relatively inexpensive; can chip and are noisy if dropped. Best for presses, slow lifts, and anywhere the bar is not dropped from height.

Bumper plates. Rubber-coated or solid rubber, all the same diameter (450 mm) regardless of weight so the bar sits at a consistent height. They are designed to be dropped from overhead (Olympic lifts) without damaging the bar, plates, or floor, and they are quieter. Calibrated competition bumpers are precise to tight tolerances.

Denominations.

• Pounds: 45, 35, 25, 10, 5, 2.5 lb.
• Kilograms: 25, 20, 15, 10, 5, 2.5, 1.25 kg.

Fractional / micro plates (e.g., 0.25, 0.5, 1 lb each) let you add tiny increments — for example, +1 lb total to a press — which keeps progressive-overload going when a 5 lb jump is too big, especially on smaller upper-body lifts.

Change plates (thin colored discs) and the bar's own weight matter when computing total load and percentages of 1RM (see intensity).

• Olympic hole = 50 mm (2 in); standard hole ≈ 1 in (not interchangeable).
• Iron/steel: compact, cheap, can chip; not for dropping.
• Bumper: uniform 450 mm diameter, rubber, made to be dropped from overhead; quieter.
• Pound plates: 45/35/25/10/5/2.5; kg plates: 25/20/15/10/5/2.5/1.25.
• Fractional plates (0.25–1 lb) enable micro-loading for continued progression.

• barbell — what plates load.
• collars-clips — keep plates from sliding.
• progressive-overload — fractional plates extend small-step progression.
• intensity — total plate load sets the %1RM.