Anal Dildo Size Guide: How to Choose the Right Size

You've found a dildo you like. The shape looks great, the colour catches your eye, and then you reach the measurements.

18 cm long. 30 mm wide.

Which number should you actually care about?

When choosing an anal dildo size, start with the widest insertable diameter. Then look at length, shape and firmness to find something that suits your experience.

Let's make those numbers a little less mysterious.

What Size Anal Dildo Should You Choose?

There's no single best anal dildo size for everyone. A good starting point is what you already know feels comfortable.

New to anal dildos? Look at slimmer, smoother designs with gradual tapers. Diameters around 25–30 mm (0.98–1.18 in) can be useful shopping references, although even these may be too large for some beginners.

Already own a toy you enjoy? Check its widest diameter. That's a much better comparison than guessing what Small or Medium means on another product.

Want something fuller? Compare the difference in diameter and the new toy's shape. A slightly wider toy with a pronounced head can feel quite different from a smooth, tapered one.

The goal isn't to find the biggest size you can manage. It's to choose one you'll actually enjoy.

Diameter, Length and Girth: What Matters?

Three measurements can tell you a lot about a dildo.

Diameter: The distance straight across the shaft. Check the widest part intended for insertion, especially if the toy has prominent bulges or a larger head.

Insertable length: How much of the toy is designed to go inside. Don't confuse this with total length, which may include the base or handle.

Girth: The circumference around the shaft. It's not the same as diameter, so check which measurement a product listing uses.

Here's the catch: a dildo advertised as 180 mm (7.09 in) long doesn't necessarily have 180 mm (7.09 in) of insertable length.

If that measurement isn't listed, it's worth checking before buying.

Let's Compare Real Anal Dildo Sizes

Two toys from our collection show why it's worth looking beyond the product photos.

7-Mode XL+ Ultimate Automatic Thrusting Dildo

Our 7-Mode XL+ Ultimate Automatic Thrusting Dildo has:

• Shaft diameter: 37 mm (1.46 in)
• Shaft length: 175 mm (6.89 in)
• Material: Silicone shaft with ABS housing
• Design: Realistic textured shaft attached to a powered thrusting unit with a separate suction base

This isn't your typical handheld dildo. The shaft is connected to a larger machine, and the automatic movement adds another factor beyond size.

But here's why it's interesting for comparison: its diameter is only 1 mm (0.04 in) wider than the Small Kraken below, despite the two toys having very different lengths and designs.

Kraken Dick Tentacle Dildo

Now compare that with our Kraken Dick Tentacle Dildo.

Two of its size options measure:

• Small: 36 mm (1.42 in) widest diameter, 280 mm (11.02 in) listed length
• Medium: 44 mm (1.73 in) widest diameter, 350 mm (13.78 in) listed length

The Small version starts with a narrower 16.9 mm (0.67 in) tip, while the Medium has a 20 mm (0.79 in) tip. Both widen into textured sections with raised suckers and ridges.

The Small Kraken is 280 mm (11.02 in) long, compared with the XL+ machine's 175 mm (6.89 in) shaft. It also has a very different shape, with raised suckers and ridges along its body.

Nearly the same diameter. Two completely different toys.

That's why choosing an anal dildo isn't just about finding the right number on a size chart.

Why Shape and Firmness Matter

Two dildos with the same widest diameter can still feel completely different.

A smooth, tapered shaft distributes its width differently from one with a pronounced head or deep ridges. Curves and firmness also change how a toy feels.

Material matters too. Flexible silicone won't behave like rigid glass, and even silicone dildos can vary in softness.

Finally, don't overlook the base. For anal use, choose a toy with a secure, substantially flared base or another reliable external stop designed to remain outside the body. A suction cup alone doesn't guarantee that.

Find Your Anal Dildo

Found a diameter that looks right? Now compare the shapes, lengths and designs that catch your eye.

Explore our Anal Dildos collection to find different sizes and styles.

If this is your first toy, our First Time Anal Dildo Guide covers preparation, lubricant and practical use.

Choose a size that suits your experience, not just one that looks impressive in a product photo.