How to Measure Dildo Size: Length, Girth, and What the Numbers Mean

Understanding how dildo dimensions are measured — and how to compare measurements between different products — is one of those small pieces of knowledge that makes every subsequent purchase easier. Here's the complete guide.

How Manufacturers Measure (and Why It's Inconsistent)

There's no industry standard for measuring and reporting sex toy dimensions. Different manufacturers measure differently, report different figures, and sometimes use different units without clearly labelling them. This creates genuine confusion when comparing products.

The most common problem: "length" in a listing could mean total length or insertable length, and it's not always clear which. When only one length figure is given, assume it's total length and mentally subtract what looks non-insertable from the product images.

Measuring Insertable Length

Insertable length is measured from the point where the body-contact surface begins (where the base meets the shaft, roughly at the perineum/anal opening in use) to the tip.

For your own reference measurement: if you know the insertable length of a toy you currently use and enjoy, that's your baseline. For a first purchase, the typical comfortable starting range is 10–14cm, but this varies by individual.

Measuring Diameter

Diameter is a straight-line measurement across the circular cross-section of the shaft. To measure a toy you already own: using flexible measuring tape, measure around the widest point of the shaft to get the circumference. Divide by π (3.14159) to get the diameter.

Circumference ÷ 3.14 = diameter

So: a toy that measures 11cm around has a diameter of approximately 3.5cm.

Converting Between Units

Some listings use centimetres; others use inches. The conversion:

• 1 inch = 2.54cm
• 1cm = 0.394 inches

Common reference conversions for insertable length:

• 4 inches = 10.2cm
• 5 inches = 12.7cm
• 6 inches = 15.2cm
• 7 inches = 17.8cm
• 8 inches = 20.3cm

Common reference conversions for diameter:

• 1 inch = 2.54cm
• 1.5 inches = 3.8cm
• 2 inches = 5.1cm

Using a Comparison Tool

When you're comparing multiple toys, a tool that normalises all dimensions to the same units and measurement standard is significantly more useful than trying to compare manufacturer-listed specs directly. Measuredpleasure.com catalogues insertable length and diameter consistently across a large range of products, which makes direct comparison practical.

This is particularly useful when listing specs use different units or different measurement points (some manufacturers measure shaft diameter at the widest point; others at the midpoint; others don't specify).

Measuring Your Own Comfort Range

The most useful personal measurement is your current comfortable insertable length and diameter. You can establish this from toys you currently use:

• Measure the actual insertable depth of a toy you find comfortable and not too long (the full length to where it feels comfortable, not necessarily the full insertable length of the toy)
• Measure the circumference of the widest toy that's comfortable, convert to diameter

These give you a clear spec range to filter within when looking for new toys.

See also: Insertable Length Guide, Dildo Girth Guide, How to Measure Girth