Standard Form A washers in zinc-plated finish, available in sizes M4 to M20. Sold in box quantities from 100 to 1250. Suitable for general clamping and spacing in most indoor and light-duty applications.
Available options and pricing for Washers - Zinc - Form A (Box Qty), with quantity selectors and a running total
Size
QTY
SKU
Price
QTY
Total
M4
1250
WA4Z
£3.27£3.92
—
M5
1000
WA5Z
£2.84£3.41
—
M6
500
WA6Z
£2.66£3.19
—
M8
200
WA8Z
£1.89£2.27
—
M10
100
WA10Z
£1.80£2.16
—
M12
100
WA12Z
£2.76£3.31
—
M14
100
WA14Z
£3.68£4.42
—
M16
100
WA16Z
£4.94£5.93
—
M20
100
WA20Z
£7.53£9.04
—
Zinc Form A washers are the standard flat washer you will find on building sites, in workshops, and in general assembly work across the country. Available in sizes from M4 through to M20, these washers are plated in Trivalent Chromium (Cr3) zinc, which gives a clean, consistent finish and a reasonable level of corrosion resistance for most everyday fixing tasks. Whether you are spreading the load under a bolt head, protecting a surface from damage, or making up the spacing on a through-bolt fixing, Form A washers earn their keep.
Form A refers to the British Standard designation for a normal series flat washer. The outer diameter and thickness are sized to suit standard bolts and nuts without being oversized. If you need a larger bearing surface, Form C (the wide series) is the one to reach for, but for most standard bolt-and-nut assemblies, Form A is exactly what is specified.
Where Zinc Form A Washers Get Used
These washers turn up in just about every trade. Carpenters use them with coach bolts through structural timber. Fabricators fit them under hex bolts on light steelwork. Electricians use them on panel fixings. Plumbers use them on bracket assemblies. If you are bolting two things together and want the connection done properly, there is a good chance a zinc Form A washer is involved somewhere.
Box Quantities
Buying in box quantities makes sense when you are running through washers at any kind of pace. Box quantities vary by size, with smaller sizes typically running to 1000 or 1250 per box, and larger sizes like M16 and M20 supplied in quantities of 100 or 200. That means you are not overpaying for packaging on the big stuff, and you are not running short on the small stuff mid-job. The zinc Form A washers are competitively priced, so stocking a range of sizes is a straightforward decision.
Pro Tip: When using zinc Form A washers with softwood timber, pair them with a larger Form C washer on the tension side if the bolt will be under sustained load, as the smaller bearing surface of a Form A can pull through softer grain over time.
Zinc Form A washers are used in general construction, joinery, light fabrication, plumbing, and electrical installation work. They are fitted under bolt heads and nuts to spread clamping load, protect surfaces from damage, and take up minor gaps in assemblies. Common applications include structural timber connections, steel bracket fixing, machine assemblies, and general fastening work where a standard flat washer is called for.
Best For
General bolt and nut assemblies
Structural timber connections
Light steelwork and fabrication
Plumbing and electrical bracket fixings
Workshop and maintenance tasks
Available In
M4
M5
M6
M8
M10
M12
M14
M16
M20
Key Properties
Trivalent Chromium (Cr3) zinc plating
Form A (normal series) to BS EN ISO 7089
Consistent sizing for standard bolt and nut compatibility
Supplied in box quantities
Suitable for indoor and light-duty outdoor use
Not suitable for: Not recommended for exposed external applications where prolonged moisture contact is expected. For demanding outdoor or marine environments, consider stainless steel washers instead.
Fit a zinc Form A washer onto the bolt shank before threading through the fixing point. Place a second washer under the nut on the reverse side where surface protection or load spreading is needed. Tighten to the appropriate torque for the bolt grade and application.
Select the correct washer size to match the bolt diameter being used
Slide the washer onto the bolt shank before inserting through the fixing
Place a second washer on the reverse side under the nut if required
Tighten the nut to the specified torque, checking the washer seats flat against the surface
What does Form A mean on a washer?
Form A refers to the normal series flat washer as defined under BS EN ISO 7089. It has a standard outer diameter and thickness proportioned to suit standard bolt and nut sizes. Form C is the wide series with a larger outer diameter, used where a greater bearing surface is needed.
Are zinc Form A washers suitable for outdoor use?
They are fine for occasional or light outdoor exposure, but the zinc Cr3 plating is not designed for prolonged contact with moisture or aggressive environments. For permanent external fixings exposed to weather, stainless steel washers are the better choice.
How do I know which box quantity I will receive?
Box quantities vary by size. Smaller sizes such as M4 and M5 are supplied in larger quantities, typically 1000 or 1250 per box, while larger sizes such as M16 and M20 are supplied in smaller quantities. The box quantity is shown as a product option when selecting your size.
Zinc Form A washers are manufactured to BS EN ISO 7089, defining outer diameter, inner diameter, and thickness for the normal series. The zinc plating uses Trivalent Chromium (Cr3) as the passivate layer, replacing hexavalent chromium in line with RoHS and REACH requirements. Cr3 zinc plating provides basic corrosion protection suitable for interior and dry-fit applications.
Standard
BS EN ISO 7089
Series
Form A (Normal Series)
Plating
Trivalent Chromium (Cr3) Zinc
Sizes Available
M4, M5, M6, M8, M10, M12, M14, M16, M20
Box Quantities
100, 200, 500, 1000, 1250 (varies by size)
Size
M10, M12, M14, M16, M20, M4, M5, M6, M8
Box Quantity
100, 1000, 1250, 200, 500
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