Bolts

Choose the bolt type

• Hex bolts: general-purpose hex head bolts in low carbon steel, A307 Grade A and Grade 8, plain, zinc or hot-dip galvanized, up to 2-1/2" diameter.
• Carriage bolts: round head with a square neck that holds the bolt in wood or a square hole while you tighten the nut. Inch #6 to 7/8" and metric M5 to M16.
• Lag bolts (lag screws): hex head with a wood thread, driven into timber with no nut. Inch and metric (M6 to M12).
• Tap bolts: hex head bolts threaded the full length, used with a nut or in a tapped hole. Grade 5, Grade 8, low carbon and 18-8 stainless.
• Flange bolts: hex head with a flange under the head that spreads the load like a washer, serrated or non-serrated. Inch Grade 5 and 8, metric Class 8.8 and 10.9, and stainless.
• Square head bolts, plow bolts (No. 3, dome and large head), hanger bolts, elevator bolts, step bolts, timber bolts and anchor bolts.
• For high-strength and structural work, see heavy hex bolts, A325 and A490 structural bolts and hex cap screws.

Material and grade

Steel bolts are listed as low carbon steel, A307 Grade A, SAE Grade 2, Grade 5 or Grade 8, or metric Class 8.8 and 10.9. Use the grade your drawing or the original part calls for. Inch stainless is 18-8 or 316. Metric stainless is A2 or A4, for example A4-70 carriage bolts. Some hex cap screws also come in silicon bronze. The material is named in each product title.

Shop by grade: Grade 5, Grade 8, Class 8.8, Class 10.9, 18-8 stainless and 316 stainless.

Thread and size callouts

Inch bolts are listed as diameter-threads per inch x length. 1/2"-13 x 3" is a 1/2" coarse thread (UNC) bolt, 3" long. 1/2"-20 would be fine thread (UNF). Metric bolts list diameter, pitch and length: M10-1.5 x 40 mm. Titles also say partial thread or full thread where it applies. Lag bolts have a wood thread, so they list diameter and length only.

Finish

Steel finishes include plain, zinc, zinc yellow, hot-dip galvanized, black oxide and black phosphate. Plain steel has no coating. Zinc plating is a thin coating, best for indoor or dry use. Hot-dip galvanizing is much thicker and suits outdoor or wet use; pair it with galvanized nuts from the same coating process. Stainless is passivated. The finish is the last item in each title. See hot-dip galvanized.

Head and drive

Hex, heavy hex, flange and square heads take a wrench or socket. Carriage and step bolts have a round head and a square neck that stops the bolt turning, so you only wrench the nut. Elevator bolts have a flat countersunk head and a square neck. Plow bolts have a countersunk head that sits flush. Hanger bolts have no head: a wood thread on one end and a machine thread on the other. For wrench sizes by bolt diameter, see the wrench size chart.

Length

Hex, square, carriage and lag bolt length is measured from under the head to the end. Countersunk heads such as plow and elevator bolts are measured overall, including the head.

Packages and bulk boxes

Most bolts come as a Package or a Bulk Box. Piece counts depend on size, for example 20 / 200 or 45 / 450. Each variant shows its count. Need volume pricing? See wholesale.