How big is a bed bug?

An adult bed bug is about 4 to 7 millimeters long — roughly the size of an apple seed. Newly hatched nymphs are about 1 to 1.5 mm and nearly translucent, growing and darkening through five stages to adulthood.

Can you see bed bugs with the naked eye?

Yes. Adult and later-stage bed bugs are visible to the naked eye at 4–7 mm. The youngest nymphs (about 1 mm) and the eggs (about 1 mm, pearl-white) are visible but easy to miss without close inspection.

What is commonly mistaken for a bed bug?

Carpet beetles, bat bugs, spider beetles, booklice, and young cockroaches are the most common lookalikes. Carpet beetles are rounder and patterned; bat bugs are nearly identical but hairier; fleas are narrow and jump.

Is This a Bed Bug? Size Comparison & Identification Tool

01 / Size

Compare the size

Set the life stage and a reference object, then calibrate to your screen for a true 1:1 scale. Hold your specimen up to the ruler to compare against a real bed bug.

true scale: calibrate →

Life stage & size Adult, unfed 5.0 mm · drag for any size 1–9 mm

Sizes are approximate until you calibrate. Calibration uses a standard bank/credit card (85.6 mm wide) so the bug shows at true real-world size on your device.

What it really looks like

The slider shows scale; this is a real adult bed bug from the CDC for color, shape, and texture. Compare both to what you found.

Full appearance guide →

02 / Rule out

Is it actually a bed bug?

These five get mistaken for bed bugs constantly. Tap each to see what gives it away.

03 / Act

It's a bed bug. Now what?

Move fast — a female lays hundreds of eggs and infestations only grow. Two paths, depending on how far it's gone.

Caught it early? Start DIY tonight.

One or two bugs, caught before it spreads, can often be handled yourself. The order that actually works: encase, intercept, monitor, treat.

Spreading, or in multiple rooms? Get a pro.

Once bed bugs reach several rooms or you're seeing them regularly, DIY usually loses. Professional treatment runs $300–$5,000 depending on severity — early pro treatment is the cheaper end.

Free, no-obligation quotes. We may earn a referral fee — it never changes your price.

Some links above are affiliate or referral links. If you buy or request a quote through them, we may earn a commission at no extra cost to you. We only list EPA-registered products and licensed providers, and recommendations are based on pest-control and university extension guidance — not on who pays most. Full disclosure.

Recommended gear

What actually works on bed bugs

The core toolkit pest pros and university extension programs point to, in the order you'd use it. Prices and availability on Amazon — always follow each product's label.

As an Amazon Associate we earn from qualifying purchases. These are affiliate links: if you buy through them we may earn a commission at no extra cost to you. Product selection reflects published pest-control and university extension guidance, not commission. Full disclosure.

Bed bug size, at a glance

Adult length: 4–7 mm (apple-seed sized)
Newly hatched: ~1–1.5 mm, translucent
Egg: ~1 mm, pearl-white
Shape: Flat oval — balloons & reddens after feeding
Color: Pale tan → mahogany brown
Visible to eye?: Yes, all stages (eggs are tiny)

You found a bug.Let's settle it.