Centering Rulers | McMaster-Carr

	System of Measurement System of Measurement

Inch

Metric

Half Measure Inch

	Length Length

	Width Width

1 1/4"

	Thickness Thickness

0.004"

1/32"

3/32"

	Material Material

	Reading Direction Reading Direction

	Graduation Marks Graduation Marks

	Numeric Increments Numeric Increments

1/10"

4/32"

10 mm

	Graduation Location Graduation Location

	Graduation Mark Style Graduation Mark Style

Etched

Printed

	Orientation Orientation

Horizontal

Vertical

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	Blade Length Blade Length

	Blade Width Blade Width

5/8"

3/4"

	Blade Thickness Blade Thickness

1/16"

5/64"

3/32"

	Square Head Material Square Head Material

Iron

Steel

Aluminum

	Component Component

Blade

Square Head with Built-in
Level

Center Head

Square Head

	Blade Color Blade Color

	Silver
	Yellow
	Gold

	Center Head Material Center Head Material

Iron

Steel

Aluminum

	Head Length Head Length

	Numeric Marks Numeric Marks

Center Point

Feet

Inches

	Segment Length Segment Length

1 1/2 ft.

3 ft.

3 3/4 ft.

	Manufacturer Model Number Manufacturer Model Number

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78 Products

Center-Finding Rulers

Inch

Inch/Metric

Zero marks the center when these rulers are positioned so the same number touches each side of an object. All are corrosion-resistant stainless steel and have wear-resistant etched markings. They're flexible for measuring slightly curved surfaces.

Inch—Left to Right/Right to Left Reading Direction
Lg.	Front Graduation Marks (Numeric Increments)	Back Graduation Marks (Numeric Increments)	Wd.	Thick.	Flexibility	Color	Graduation Mark Style	Hole Dia.		Each
Stainless Steel
12"	16ths (1"), 32nds (1")	__	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	00000
18"	16ths (1"), 32nds (1")	__	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	0000
24"	16ths (1"), 32nds (1")	__	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	0000
36"	16ths (1"), 32nds (1")	__	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	00000
48"	16ths (1"), 32nds (1")	__	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	00000
Inch/Metric—Left to Right/Right to Left Reading Direction
Stainless Steel
18"/45 cm	16ths (1"), 16ths (1")	Millimeters (1 cm), Millimeters (1 cm)	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	00000
24"/60 cm	16ths (1"), 16ths (1")	Millimeters (1 cm), Millimeters (1 cm)	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	00000
36"/90 cm	16ths (1"), 16ths (1")	Millimeters (1 cm), Millimeters (1 cm)	1 1/4"	1/32"	Flexible	Silver	Etched	1/4"	0000000	00000

Half-Measure Adhesive-Back Rulers

Left to Right

Right to Left

Use to find diameters and centers. The graduations and numeric increments on these rulers are half the actual length of the object you are measuring; a 1" graduation is actually 1/2", a 2" graduation is actually 1", and so on. All are flexible for mounting on curved surfaces.

								Segments
Lg.	Front Top Graduation Marks (Numeric Increments)	Front Bottom Graduation Marks (Numeric Increments)	Wd.	Thick.	Flexibility	Color	Graduation Mark Style	No. of	Lg., ft.		Each
Half-Measure Inch—Left to Right Reading Direction
Plastic
1 1/2 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	1 1/2	00000000	00000
3 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	3	00000000	0000
6 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	2	3	00000000	00000
7 1/2 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	2	3 3/4	00000000	00000
11 1/4 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	3	3 3/4	00000000	00000
Half-Measure Inch—Right to Left Reading Direction
Plastic
1 1/2 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	1 1/2	00000000	0000
3 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	3	00000000	0000
6 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	2	3	00000000	00000
7 1/2 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	2	3 3/4	00000000	00000
11 1/4 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	3	3 3/4	00000000	00000

Half-Measure Adhesive-Back Vertical Rulers

Bottom to Top

Top to Bottom

The graduations and numerical increments on these rulers are half the actual length of the object you are measuring; a 1" graduation is actually 1/2", a 2" graduation is actually 1", and so on. Use them to find diameters and centers. All are flexible for mounting on curved surfaces.

								Segments
Lg.	Front Left Graduation Marks (Numeric Increments)	Front Right Graduation Marks (Numeric Increments)	Wd.	Thick.	Flexibility	Color	Graduation Mark Style	No. of	Lg., ft.		Each
Half-Measure Inch—Bottom to Top Reading Direction
Plastic
1 1/2 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	1 1/2	00000000	00000
3 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	3	00000000	0000
Half-Measure Inch—Top to Bottom Reading Direction
Plastic
1 1/2 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	1 1/2	00000000	0000
3 ft.	8ths (1")	8ths (1")	1"	0.004"	Flexible	Silver	Printed	1	3	00000000	0000

Center-Finding Tape Measures

Find the exact center of your work. Measure the total distance with the upper scale; then find the same number on the bottom scale—that's your center point. The blade is coated to resist scratches, wear and corrosion. It locks in place. Case is impact-resistant plastic with a nonslip rubber grip. It's yellow for high visibility.

			Blade				Graduation
Lg.	Graduation Marks	Numeric Marks	Width	Material	Color	Tip Style	Color	Mark Style		Each
Inch
16 ft.	16ths	Inches, Feet, Center Point	3/4"	Coated Steel	Yellow	Hook	Black	Printed	0000000	000000
25 ft.	16ths	Inches, Feet, Center Point	1"	Coated Steel	Yellow	Hook	Black	Printed	0000000	00000

High-Accuracy Combination Square Blades

Inch

Blades are for use with High-Accuracy Combination Square Heads. Blades are labeled with numeric increments that are less than 1" for quick-reading. All have a corrosion-resistant satin-chrome finish that reduces glare and wear-resistant etched markings.

							Graduation
Lg.	Front Graduation Marks (Numeric Increments)	Back Graduation Marks (Numeric Increments)	Accuracy	Wd.	Thick.	Color	Color	Mark Style		Each
Inch
Satin-Chrome Steel
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Silver	Black	Etched	00000000	000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0025" to +0.0025"	1"	3/32"	Silver	Black	Etched	00000000	00000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Silver	Black	Etched	00000000	00000
18"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0025" to +0.0025"	1"	3/32"	Silver	Black	Etched	00000000	00000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Silver	Black	Etched	00000000	00000
24"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0025" to +0.0025"	1"	3/32"	Silver	Black	Etched	00000000	00000

High-Accuracy Combination Square Heads

Center Head

Attach to High-Accuracy Combination Square Blades with the included lockbolts. Center head identifies the center on pipes, rods, and shafts.

Hardened cast iron heads are more durable and last longer than cast iron heads.

Cast Iron
Component	For Blade Lgs.		Each
Center Head	12"-24"	00000000	000000
Hardened Cast Iron
Center Head	12"-24"	00000000	00000

Replacement Lockbolt

00000000

Each

00000

High-Accuracy Combination Squares

Use these squares in place of your try square, miter square, depth gauge, height gauge, center-point finder, and level. Blades are labeled with numeric increments that are less than 1" for quick reading. All have a corrosion-resistant satin-chrome finish that reduces glare and wear-resistant etched markings.

Square head checks 90° angles. Center head identifies the center on pipes, rods, and shafts. Protractor head measures angles.

Hardened cast iron heads are more durable and last longer than cast iron heads.

Blade with Square Head with Built-in Level, Center Head, and Scriber

Inch

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Heads
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	0000000
Hardened Cast Iron Heads
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	000000

Replacement Lockbolt

00000000

Each

00000

Blade with Square Head with Built-in Level, Center Head, Reversible Protractor Head, and Scriber

Inch

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Heads
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	0000000
Hardened Cast Iron Heads
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	000000

Replacement Lockbolt

00000000

Each

00000

Combination Squares

Replace your try square, miter square, depth gauge, marking gauge, 90° level, ruler, and scriber with one tool. Blades labeled with numeric increments that are less than 1" are quick-reading. All have wear-resistant etched markings.

Square head checks 90° angles.

Center head identifies the center on pipes, rods, and shafts.

Protractor head measures angles.

Blade with Square Head with Built-in Level, Center Head, Reversible Protractor Head with Built-in Level, and Scriber

Inch/Metric

			Blade				Graduation			Aluminum Heads
Blade Lg.	Front Graduation Marks (Numeric Increments)	Back Graduation Marks (Numeric Increments)	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch/Metric
12"/300mm	Millimeters (10 mm), 32nds (4/32")	Millimeters (10 mm), 16ths (1")	1"	3/32"	Steel	Silver	Black	Etched	4 1/4"	000000	000000

Starrett High-Accuracy Combination Squares

Replace your try square, miter square, depth gauge, height gauge, center-point finder, and level. The blade on these squares meets Fed. Spec. GGG-R-791H, which establishes uniform standards for accuracy, graduations, and size. Blades are labeled with numeric increments that are less than 1" for quick reading. All have wear-resistant etched markings. Protractor head measures angles.

Blade with Square Head and Center Head

Inch

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Heads
Inch
4"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	5/8"	1/16"	Satin-Chrome Steel	Silver	Black	Etched	2 1/4"	0000000	0000000
Hardened Steel Heads
Inch
4"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	5/8"	1/16"	Satin-Chrome Steel	Silver	Black	Etched	2 1/4"	0000000	000000

Replacement Lockbolt for Square and Center Heads

0000000

Each

000000

Blade with Square Head with Built-in Level, Center Head, and Scriber

Inch

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Heads
Inch
6"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	3/4"	5/64"	Satin-Chrome Steel	Silver	Black	Etched	2 13/32"	0000000	0000000
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
Hardened Steel Heads
Inch
6"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	3/4"	5/64"	Satin-Chrome Steel	Silver	Black	Etched	2 13/32"	0000000	000000
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000

Replacement Lockbolt for Square, Center, and Protractor Heads	0000000	Each	00000
Replacement Lockbolt for Center Heads	0000000	Each	00000
Replacement Lockbolt for Square and Center Heads	0000000	Each	00000

Blade with Square Head with Built-in Level, Center Head, Protractor Head, and Scriber

Inch

				Blade				Graduation			Cast Iron Heads
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	0000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000

Replacement Lockbolt for Square, Center, and Protractor Heads

0000000

Each

00000

Blade with Square Head with Built-in Level, Center Head, Reversible Protractor Head, and Scriber


	Inch
	Inch/Metric

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Heads
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	0000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
Inch/Metric
11 3/4"/300mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (8/64")	-0.0035" to +0.005"/-0.09 mm to +0.15 mm	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
23 1/2"/600mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (8/64")	-0.0035" to +0.007"/-0.11 mm to +0.25 mm	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
Hardened Steel Heads
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.006"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.007"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
Inch/Metric
11 3/4"/300mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (8/64")	-0.0035" to +0.005"/-0.09 mm to +0.15 mm	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000
23 1/2"/600mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (8/64")	-0.0035" to +0.007"/-0.11 mm to +0.25 mm	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	3 5/8"	0000000	000000

Replacement Lockbolt for Square, Center, and Protractor Heads

0000000

Each

00000

Starrett High-Accuracy Combination Square Heads

Attach to Starrett High-Accuracy Combination Square Blades with the included lockbolts. Center head identifies the center on pipes, rods, and shafts.

Hardened-steel heads are more durable and last longer than cast iron heads.

Center Head

Cast Iron
Component	For Blade Lgs.		Each
Center Head	4"	0000000	000000
Center Head	6"	0000000	00000
Center Head	12"-48"	0000000	00000
Hardened Steel
Center Head	4"	0000000	00000
Center Head	6"	0000000	000000
Center Head	12"-48"	0000000	00000

Replacement Lockbolts

For Head Style	For Blade Lgs.		Each
Center	6"	0000000	000000
Square, Center	4"	0000000	00000
Square, Center	6"	0000000	00000
Square, Center, Protractor	12"-36"/300 mm-600 mm	0000000	0000

Scratch-Resistant High-Accuracy Combination Squares

A titanium coating protects the blade against scratches and wear. Use these squares to replace your try square, miter square, depth gauge, height gauge, center-point finder, and level. Blades are labeled with numeric increments that are less than 1" for quick reading. All have wear-resistant etched markings.

Square head checks 90° angles. Center head identifies the center on pipes, rods, and shafts. Protractor head measures angles.

Blade with Square Head with Built-in Level, Center Head, Protractor Head, and Scriber

Inch

				Blade				Graduation			Cast Iron Heads
Blade Lg.	Front Graduation Marks (Numeric Increments)	Back Graduation Marks (Numeric Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.002"	1"	3/32"	Titanium-Coated Steel	Gold	Black	Etched	4 1/2"	00000000	0000000