What is the difference between a speed square and a framing square?

A speed square is a compact triangle used for quick angle marking, saw guides, and rafter layout on individual boards. A framing square is a larger L-shaped tool used for stair layout, checking large assemblies for square, and more detailed rafter calculations. Most carpenters carry both.

How do I use a speed square as a saw guide?

Hold or clamp the fence against the board edge. Rest the circular saw's shoe against the straight edge of the square. Make your cut while keeping the shoe pressed against the square. This produces a perfectly straight 90-degree crosscut.

How do I mark rafter angles with a speed square?

Find the roof pitch on the common rafter scale (printed on the hypotenuse). Pivot the square so that degree mark aligns with the board edge while the pivot point stays on the rafter edge. Draw the plumb cut line along the perpendicular edge.

Measuring & Layout

$5-$10 for basic 7-inch, $10-$20 for premium 7-inch (Swanson), $15-$25 for 12-inch models, $20-$35 for adjustable or specialty squares.

The Complete Guide to Speed Squares (2026)

Prepared by Lumberama's Tools & Equipment Team

|Last updated May 26, 2026|Sources & methodology

The speed square (officially the Swanson Speed Square) is a versatile triangular layout tool that combines the functions of a try square, miter square, protractor, line scriber, and saw guide into one compact, indestructible tool. Made from aluminum or high-impact plastic, it is the most-used layout tool on framing job sites and an essential in every toolbox.

Key Takeaways

The speed square (officially the Swanson Speed Square) is a versatile triangular layout tool that combines the functions of a try square, miter square, protractor, line scriber, and saw guide into one compact, indestructible tool.
Made from aluminum or high-impact plastic, it is the most-used layout tool on framing job sites and an essential in every toolbox.
Speed squares are used for marking 90-degree crosscut lines, marking 45-degree miter lines, scribing rafter angles using the degree and common rafter scales, serving as a circular saw guide for short crosscuts, checking boards for square, laying out stair stringers with the stair gauge feature, and marking any angle from 0-90 degrees using the pivot point.
Material (aluminum vs composite), size (7 or 12 inch), legible engraved markings (not printed), degree scale in 1-degree increments, common rafter table, hip/valley rafter markings, scribing notches, diamond-cut pivot point, and a reference book (included with Swanson).

What It's Used For

Speed squares are used for marking 90-degree crosscut lines, marking 45-degree miter lines, scribing rafter angles using the degree and common rafter scales, serving as a circular saw guide for short crosscuts, checking boards for square, laying out stair stringers with the stair gauge feature, and marking any angle from 0-90 degrees using the pivot point.

Types & Variations

Standard 7-inch (pocket-sized, for dimensional lumber), 12-inch (for wider boards and more visibility), Trim/Compact (4.5-inch for small work), Adjustable (locking protractor arm), Aluminum (durable, standard), Composite/Plastic (lighter, won't scratch wood), and Stainless Steel (corrosion-resistant for outdoor use).

Key Features to Look For

Material (aluminum vs composite)
size (7 or 12 inch)
legible engraved markings (not printed)
degree scale in 1-degree increments
common rafter table
hip/valley rafter markings
scribing notches
diamond-cut pivot point
and a reference book (included with Swanson).

How to Use

1) For 90-degree crosscut lines: Press the fence (the raised lip) firmly against the edge of the board. Draw a line along the perpendicular edge. 2) For 45-degree miters: Press the fence against the board edge and align the 45-degree mark. Draw along the hypotenuse. 3) For any angle: Pivot the square on its corner, aligning the desired degree mark with the board edge. 4) As a saw guide: Clamp or hold the fence against the board and run the circular saw shoe along the straight edge. 5) For rafter layout: Use the rafter tables and common rafter scale to mark plumb and seat cuts.

⚠️ Safety Tips

When using as a circular saw guide, ensure the square is held firmly or clamped — do not let the saw push it. Keep fingers well clear of the saw path. Metal speed squares can scratch finished surfaces — use a composite square for trim work. Be aware of sharp edges on aluminum models.

Maintenance

Clean markings occasionally with a soft brush to maintain readability. Check for straightness by placing against a known flat edge. Aluminum squares can be trued on sandpaper if they become slightly bent. Do not drop — impacts can bend the fence. Store in a dry location. The tool is essentially maintenance-free and lasts a lifetime.

Price Range & Recommendations

Price Range: $5-$10 for basic 7-inch, $10-$20 for premium 7-inch (Swanson), $15-$25 for 12-inch models, $20-$35 for adjustable or specialty squares.

Beginners should get the Swanson S0101 7-inch Speed Square ($10) — it comes with the Blue Book of rafter layout instructions and is the original and best. Add a 12-inch version for wider boards. Pros will carry both sizes and may prefer the Swanson Big 12 or the Johnson 1904 aluminum combo with stair gauges. Woodworkers often prefer the Woodpeckers precision squares for shop use.