Crab Gauge Guide: Legal Sizes and How to Measure Crab

Crab Gauge Guide: Legal Sizes, How to Measure Crab, and Choosing the Right Gauge

A crab gauge is one of the most important tools you can bring on a crabbing trip. Every state has a minimum legal size for the crabs you keep, and keeping an undersized crab can result in a significant fine. A good gauge makes measuring fast, accurate, and easy so you spend more time crabbing and less time guessing. This guide covers how to measure crab correctly, legal sizes by species and state, and how to choose the right gauge for your fishing.

Why You Need a Crab Gauge

Crab size limits exist to protect juvenile crabs and maintain healthy populations for future seasons. Regulations are enforced on the water and at the dock. Wardens check catches regularly, especially during peak Dungeness and blue crab season. An undersized crab in your bucket is not worth the fine or the damage it does to the fishery long term.

A crab gauge removes any guesswork. Instead of eyeballing a crab and hoping it is legal, you measure it in seconds and know for certain. It is a small piece of gear that makes a big difference.

How to Measure a Crab

Dungeness Crab

Dungeness crab are measured across the widest part of the carapace, which is the hard upper shell. Place the gauge across the shell at its widest point, perpendicular to the centerline of the crab. The measurement must meet or exceed the minimum legal size for your state. In California, Oregon, and most of Washington, that minimum is 5.75 inches for Dungeness.

Blue Crab

Blue crab are measured point to point, from the tip of one lateral spine to the tip of the other across the widest part of the shell. The standard minimum size for blue crab in most East Coast states is 5 inches point to point for hard shell crabs. Soft shell crabs have different regulations depending on the state.

Rock Crab

Rock crab in California are measured across the widest part of the carapace. The minimum size for red rock crab is 4 inches and for yellow rock crab is 4 inches in most California zones. Always verify with CDFW for your specific area.

Lobster

California spiny lobster are measured from the rear edge of the eye socket to the rear edge of the body shell along the centerline. The minimum carapace length in California is 3.25 inches. East Coast American lobster are measured from the rear of the eye socket to the rear of the carapace along the centerline, with a minimum of 3.25 inches in most New England states.

Legal Crab Sizes by State

California

  • Dungeness crab — 5.75 inches across widest part of carapace. Males only.
  • Red rock crab — 4 inches across widest part of carapace.
  • Yellow rock crab — 4 inches across widest part of carapace.
  • Spiny lobster — 3.25 inch minimum carapace length.

Oregon

  • Dungeness crab — 5.75 inches across widest part of carapace. Males only.
  • Red rock crab — no minimum size, males only.

Washington

  • Dungeness crab (Puget Sound) — 6.25 inches across widest part of carapace. Males only.
  • Dungeness crab (coastal) — 5.75 inches. Check WDFW for your specific management area.
  • Red rock crab — no minimum size in most areas. Males only.

Maryland

  • Blue crab (hard shell) — 5 inches point to point.
  • Blue crab (soft shell) — 3.5 inches point to point.
  • Sponge crabs (females with eggs) — must be returned immediately.

Virginia

  • Blue crab (hard shell) — 5 inches point to point.
  • Blue crab (soft shell) — 3.5 inches point to point.

North Carolina

  • Blue crab — no minimum size for recreational crabbers in most areas, though check current regulations as rules can vary by season and location.

Louisiana and Texas

  • Blue crab — 5 inches point to point in Texas. Louisiana has no minimum size for recreational crabbers but check current LDWF regulations.

The AirFly Crab and Lobster Gauge Lineup

AirFly Aluminum Crab and Lobster Gauge

An all-in-one aluminum gauge that measures five sizes in one tool: 3 inches, 3.25 inches, 4 inches, 5 inches, and 5.75 inches. Covers Dungeness, rock crab, and lobster measurements for California, the Pacific Northwest, and East Coast waters. Built from corrosion-resistant aluminum that holds up in saltwater season after season. Designed in the USA.

AirFly Dungeness Crab Gauge

A compact, pocket-sized gauge specifically designed for Dungeness crab measurement on the West Coast. Available in green and in an orange and green combination. Concave design that conforms to the curved shell of the crab for a more accurate measurement. Legal for California, Oregon, and Washington.

AirFly Aluminum Lobster and Blue Crab Gauge

Covers measurements for California spiny lobster and blue crab from the East Coast to Canada. Rust-resistant aluminum, slim profile that fits in any pocket or tackle box.

AirFly Folding Fish Measuring Board

A 32-inch folding ruler with built-in gauges for Dungeness crab, blue crab, and lobster. Designed for use on boats, kayaks, and shore. Orange color for high visibility. Folds flat for easy storage.

How to Choose the Right Crab Gauge

The right gauge depends on where you fish and what you target:

  • West Coast Dungeness crabbers — the AirFly Dungeness Crab Gauge covers everything you need for California, Oregon, and Washington in a compact, pocket-sized design.
  • Crabbers who also target lobster or multiple crab species — the AirFly Aluminum Crab and Lobster Gauge covers five measurements in one tool and works for both coasts.
  • East Coast blue crab and lobster — the AirFly Aluminum Lobster and Blue Crab Gauge is designed specifically for East Coast measurements from Maine to the Gulf.
  • Boat and kayak crabbers — the AirFly Folding Fish Measuring Board gives you a full ruler plus crab and lobster gauges in one compact package.

Tips for Measuring Crab Correctly

  • Measure every crab. Do not eyeball it. Crabs that look legal often are not, especially smaller males just under the limit.
  • Measure at the widest point. For Dungeness, this means across the carapace at its widest, not near the front or back of the shell.
  • Hold the crab still. Use gloves when handling crab. A crab that is moving is hard to measure accurately and can pinch.
  • Return females immediately. For Dungeness on the West Coast, only males may be kept. Return females to the water right away.
  • Check regulations before every trip. Size limits and season dates can change. Always verify with your state fish and wildlife agency before you go.

Male vs Female Crab: How to Tell the Difference

For Dungeness crab, only males may be kept in California, Oregon, and Washington. Telling the difference is straightforward once you know what to look for.

Flip the crab over and look at the underside of the shell. The abdomen, the flap that folds under the body, tells you the sex. On a male, the abdomen is narrow and pointed, roughly T-shaped. On a female, the abdomen is wide and round, covering most of the underside. Return all females to the water immediately.

For blue crab on the East Coast, the same method applies. Male blue crabs have a narrow, T-shaped abdomen. Females have a wide, rounded abdomen. Regulations on female blue crab vary by state, so check your local rules.

Frequently Asked Questions About Crab Gauges

What is the minimum size for Dungeness crab in California?

5.75 inches measured across the widest part of the carapace. Only male Dungeness may be kept. The season runs from mid-November through June, though exact dates vary by zone. Always check CDFW before your trip.

What is the minimum size for Dungeness crab in Washington?

6.25 inches in Puget Sound. 5.75 inches for coastal areas. Check WDFW for your specific management area as rules can vary.

Do I need a gauge to go crabbing?

You are not legally required to carry a gauge in most states, but you are legally required to keep only crabs that meet the minimum size. Not having a gauge makes it very difficult to be certain your catch is legal. Carrying one is always the right call.

What is the easiest gauge to use for beginners?

The AirFly Dungeness Crab Gauge is the simplest option for West Coast beginners. Place it across the shell at the widest point. If the shell fits within the gauge, the crab is undersized and must be returned. If it does not fit, the crab is legal to keep.

Can one gauge cover multiple species?

Yes. The AirFly Aluminum Crab and Lobster Gauge covers five measurements in one tool, making it suitable for Dungeness, rock crab, and lobster across multiple states. It is the best option if you fish in multiple locations or target more than one species.

How do I measure a blue crab?

Blue crab are measured point to point, from the tip of one lateral spine to the tip of the other across the widest part of the shell. The minimum in most East Coast states is 5 inches. Use a gauge designed for blue crab to get an accurate reading.

Know Before You Go

Crab regulations change. Season dates, size limits, and bag limits are updated regularly by state fish and wildlife agencies. Before every trip, check the current rules for your state and the specific body of water you are fishing. The California Department of Fish and Wildlife, Oregon Department of Fish and Wildlife, and Washington Department of Fish and Wildlife all publish current regulations online.

Carrying the right gauge and knowing how to use it keeps you legal, protects the fishery, and means more crabs for everyone next season.

Browse the full AirFly gauge lineup and find the right tool for your crabbing location.