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Heavy Square Washers
Washers are named by the bolt they fit: an M10 washer suits an M10 bolt. The inside diameter is slightly larger than the bolt so it slides on. Our guide covers every size and washer type we stock.
Measure the inside diameter (ID), outside diameter (OD) and thickness, as shown in the drawing.
MATERIALS AND FINISHES
Galvanised Mild Steel — Hot-dip galvanised. The most common option for outdoor timber, treated pine, sleepers and retaining walls.
Zinc Yellow Mild Steel — Yellow chromate finish, attractive appearance for visible applications.
A4-70 G316 Marine Grade Stainless — For coastal timber framing, marine structures, or anywhere within 300 metres of the sea. Largely non-magnetic.
TYPICAL APPLICATIONS
Coach bolts and coach screws into timber. Retaining wall and sleeper construction. Pergola and deck framing. Structural steel where a larger bearing surface is needed. Landscaping where the washer needs to hold against the grain of treated timber.
WHY AUSTRALIA TRUSTS BOLT & NUT
With 15+ years selling fasteners online from Brisbane, we hold over 25,000 stock lines and 200 million pieces — 98.75% of online orders placed before 1pm leave same day. Save more as you buy more — we offer up to 13 price breaks plus 3 spend-tier discounts. Read our customer reviews or get in touch if you need help picking the right heavy square washer.
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M8 (5/16") x 38mm x 38mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.187 each -
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M10 x 38mm x 38mm x 3mm Zinc Yellow Heavy Square Washers Low Tensile HEC StandardAs low as $0.119 each -
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M10 x 38mm x 38mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.153 each -
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M10 x 50mm x 50mm x 3mm Stainless A4-70 G316 Heavy Square Washers HEC StandardAs low as $1.020 each -
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M10 x 50mm x 50mm x 3mm Zinc Yellow Heavy Square Washers Low Tensile HEC StandardAs low as $0.289 each -
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M10 x 50mm x 50mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.238 each -
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M10 x 50mm x 50mm x 5mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.850 each -
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M12 (1/2") x 38mm x 38mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.272 each -
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M12 (1/2") x 50mm x 50mm x 3mm Stainless A4-70 G316 Heavy Square Washers HEC StandardAs low as $1.122 each -
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M12 (1/2") x 50mm x 50mm x 3mm Zinc Yellow Heavy Square Washers Low Tensile HEC StandardAs low as $0.247 each -
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M12 (1/2") x 50mm x 50mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.272 each -
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M12 (1/2") x 50mm x 50mm x 5mm Zinc Yellow Heavy Square Washers Low Tensile HEC StandardAs low as $0.289 each -
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M12 (1/2") x 50mm x 50mm x 5mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.850 each -
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M12 (1/2") x 65mm x 65mm x 5mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.850 each -
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M14 (9/16") x 50mm x 50mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.272 each -
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M16 (5/8") x 50mm x 50mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.306 each -
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M16 (5/8") x 50mm x 50mm x 5mm Stainless A4-70 G316 Heavy Square Washers HEC StandardAs low as $1.122 each -
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M16 (5/8") x 50mm x 50mm x 5mm Zinc Yellow Heavy Square Washers Low Tensile HEC StandardAs low as $0.374 each -
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M16 (5/8") x 50mm x 50mm x 5mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.850 each -
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M16 (5/8") x 65mm x 65mm x 5mm Zinc Yellow Heavy Square Washers Low Tensile HEC StandardAs low as $0.536 each -
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M16 (5/8") x 65mm x 65mm x 5mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.850 each -
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M20 (3/4") x 50mm x 50mm x 3mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.323 each -
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M20 (3/4") x 50mm x 50mm x 5mm Stainless A4-70 G316 Heavy Square Washers HEC StandardAs low as $2.601 each -
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M20 (3/4") x 65mm x 65mm x 5mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.850 each -
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M24 (1") x 65mm x 65mm x 5mm Galvanised Heavy Square Washers Low Tensile HEC StandardAs low as $0.850 each -
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M24 (1") x 75mm x 75mm x 6mm Stainless A4-70 G316 Heavy Square Washers HEC StandardAs low as $5.950 each -
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Square heavy washers are flat plate washers ideal for even load spreading in timber or structural steel. The larger square bearing surface helps prevent the bolt head from sinking into softwood or treated pine, and the corners give extra purchase against rotation in landscaping and retaining wall applications.
TECHNICAL RESOURCES
Need help identifying your washer? See our washer measuring guide, or check the washer gauge sizing chart.
Key charts and specification sheets: Metric to Imperial Chart · Specs - Square Heavy Washers Metric Galvanised · Specs - Square Heavy Washers Metric Zinc Yellow · Specs - Square Heavy Washers Metric Stainless G316
For full sizing data and standards, see our Technical PDFs library.
