Speed Square vs Rafter Square: What's the Difference?

This is one of the most common questions I hear from people getting into carpentry, and the answer is simpler than you'd expect: a speed square and a rafter square are the same tool. The names refer to the same triangular carpenter's square. The confusion exists because of trademark history, regional preferences, and manufacturer marketing.

Let me clear it up once and for all.

The Short Answer

A "speed square" and a "rafter square" are two names for the same tool — a right-triangle carpenter's square with a fence (raised lip) along one edge, degree markings, and rafter pitch scales. You can use the names interchangeably.

The situation is similar to "Band-Aid" vs. "adhesive bandage" or "Jacuzzi" vs. "hot tub." One started as a brand name and became the generic term in common usage.

Why Both Names Exist

The Swanson Speed Square (1925)

In 1925, carpenter Albert Swanson patented a triangular layout tool and trademarked the name "Speed Square." His company, the Swanson Tool Company, sold the Speed Square for decades as the only product of its kind. For most of the 20th century, if you had a triangular carpenter's square, it was a Swanson Speed Square — so the brand name and the product became synonymous.

Trademark Genericization

As other manufacturers began producing similar tools, the trademark became harder to enforce in casual usage. People called every triangular square a "speed square" regardless of who made it. Competitors used alternative names to avoid trademark issues:

• Rafter square (describes the tool's primary framing use)
• Triangle square (describes the shape)
• Rafter angle square (Swanson's original patent name)
• Layout square (describes the general function)

Over time, "rafter square" became the most widely accepted generic term, though "speed square" remains extremely common — especially among older carpenters and in certain regions.

Regional Preferences

In my experience working across Texas and traveling to trade shows nationally:

• "Speed square" is more common in the Northeast and among older carpenters
• "Rafter square" is more common in catalogs, technical writing, and newer educational materials
• "Triangle square" is heard frequently on jobsites everywhere, especially among crews with workers from diverse backgrounds
• "Magic square" pops up occasionally in the Midwest — I have no idea where that came from

None of these is wrong. They all refer to the same tool.

All the Names for This Tool

Here's a comprehensive list of names you might encounter:

Name	Origin
Speed Square	Swanson trademark (1925)
Rafter square	Generic term, describes primary use
Triangle square	Describes the shape
Rafter angle square	Swanson's original patent name
Layout square	Describes the general function
Angle square	Common in retail/hardware stores
Quick square	Brand name (Johnson Level)
Pivot square	Brand name (some manufacturers)
Magic square	Regional slang (rare)
Rapid Rafter	Brand name for the double-sided version

How a Framing Square Is DIFFERENT

This is where real confusion happens. A framing square (also called a carpenter's square or steel square) is a completely different tool:

Feature	Rafter Square	Framing Square
Shape	Right triangle	L-shaped (two legs)
Size	7" or 12" legs	24" body × 16" tongue
Fence	Yes (raised lip)	No
Portability	Fits in tool belt	Does not fit in tool belt
Rafter tables	Basic pitch scales	Comprehensive stamped tables
Saw guide	Excellent	Poor (too large and flat)
Both-face marking	Only with Rapid Rafter	No

When to use which: Use a rafter square for quick marks, angle setting, and saw guides. Use a framing square for reading comprehensive rafter tables and laying out work on wide boards. Most professionals carry both.

Types Within the Rafter Square Category

Even though all rafter squares are fundamentally the same tool, there are meaningful variations:

Standard 7-Inch Triangle

The original Swanson-style design. Compact, fits in a tool pouch, handles everything up to 2x6 lumber.

Oversized 12-Inch Triangle

Larger version for wider boards and finer angle precision. Too big for a belt pouch.

Double-Sided / Expandable (Rapid Rafter)

The Rapid Rafter hinges open to straddle lumber and mark both faces simultaneously. It's also the only expandable square on the market — adjusting to handle 1-1/2", 3", 4", and 6" timbers. Folds flat for storage. The only rafter square to win a Popular Mechanics Gear of the Year award.

CNC-Milled Premium

Precision-milled from solid aluminum billet for maximum accuracy. Higher price point ($40-60+). Examples include the TrigJig.

For a detailed comparison of specific models, see our What Is a Rafter Square guide or the Best Rafter Square 2026 roundup.

Frequently Asked Questions

Is a speed square the same as a rafter square?

Yes. They are two names for the same triangular carpenter's tool. "Speed Square" originated as a Swanson Tool Company trademark in 1925 and became a generic term over time.

Why do some people say "speed square" and others say "rafter square"?

Regional preference and habit. "Speed square" comes from the Swanson brand name. "Rafter square" is the generic descriptor. Both are correct and universally understood on jobsites.

Is a framing square the same as a speed square?

No. A framing square is a large, L-shaped tool (24" × 16") made of flat steel. A speed square (rafter square) is a small triangle (7" or 12") with a raised fence. They serve related but different purposes in carpentry.

What should I call it when buying one?

Any name works. If you search for "speed square," "rafter square," or "triangle square" at a hardware store or online, you'll find the same type of tool. Just make sure you're not accidentally buying a framing square (L-shaped) when you want a triangle square.

Which name is technically correct?

"Rafter square" is the most widely accepted generic term. "Speed Square" is technically a trademark of Swanson Tool Company. In practice, both are understood and used interchangeably by virtually everyone in the trades.