Dildo Sizes Explained: How to Choose Your First One

Short answer: for a first dildo, work from two numbers instead of a size letter — the widest circumference and the usable length. Across our four narrowest variants those land between 10.8 and 15.5 cm (4.3 to 6.1 in) around, and between 9.7 and 14.5 cm (3.8 to 5.7 in) of usable shaft.

Size labels such as XS, Small, or Medium are only useful within one product line. They are not an industry standard. Two toys marked Small can have very different widths, usable lengths, shapes, and firmness. The numbers on the product page matter more than the letter on the variant button.

This guide explains how to read those numbers, what changes the way a size feels, and how to choose without treating discomfort as a test you have to pass.

What size dildo should I start with?

Start from a reference your body already accepts. If you use fingers or another insertable product comfortably, measure that instead of relying on a generic chart. Match the widest comfortable circumference first, then decide whether the new toy should feel similar, slightly fuller, or deliberately more of a stretch. When two options are close, take the smaller one. A smaller toy can still be satisfying; a toy that feels intimidating tends to stay in the drawer.

With no reference at all, our narrowest variant is a reasonable anchor. The Thick Conqueror in XS is 10.8 cm (4.3 in) around at its widest point, roughly 3.4 cm (1.35 in) across, with 10.7 cm (4.2 in) of usable length. Width builds gradually from the tip, so you decide how far along the shaft you go rather than meeting the widest part on the way in.

How to choose a dildo size, step by step

Girth first: diameter, circumference, and the widest insertable point

Girth usually creates the clearest difference between two sizes, and it is also the number product pages describe least consistently. Product pages may list width, diameter, circumference, or a mix of all three, so it helps to know what each term means:

• Diameter is the straight line across the widest part of the shaft.
• Circumference is the distance around that same point.
• Maximum diameter may describe a knot, a bead, or a base rather than the whole insertable shaft.
• Usable or insertable diameter should refer only to the portion designed for insertion.

To convert diameter to circumference, multiply by 3.14; divide to go back. A 1.25-inch diameter is about 3.9 inches around. A 1.5-inch diameter is about 4.7 inches around. That difference looks small on a product page and is easy to feel in use. Our own figures work the same way: a widest point of 3.4 cm reads as 10.8 cm around, which sounds far bigger and is closer to what you actually notice.

Then length, and the right one

Total length can include a suction cup, a decorative base, a handle, or a section never meant to go anywhere. Insertable length is the useful measurement. A toy with seven inches of total length may offer only five inches of usable shaft, while another is insertable almost to the base.

More length is not automatically better. Some people enjoy shallow pressure and never use the full shaft. Others want extra length for grip or positioning without intending to insert all of it. If deep pressure has ever felt uncomfortable, prioritise a controllable shape and a moderate usable length. You can always stop short, but a shorter toy is easier to handle and less visually demanding on a first purchase.

A practical check is to mark the proposed insertable length on a clean ruler or measuring tape and hold it next to a toy you already own. That physical comparison settles the question faster than any number on a screen.

Vaginal and anal sizing are not identical

For vaginal use, start from your own comfortable baseline. Width, depth sensitivity, pelvic-floor tension, and the amount of warm-up needed vary widely. Choose a toy that lets you control both angle and depth. If you are deciding between a longer slim toy and a shorter thick toy, work out whether deep pressure or stretching is the sensation you actually want; they are separate choices.

For anal use, pick only a design with a clearly flared, non-insertable base, start slimmer than you would vaginally, use generous compatible lubricant, move slowly, and stop for sharp or escalating pain. The tissue is more vulnerable to tearing, and numbness is not a goal. Cleveland Clinic's anal safety guidance also recommends avoiding large or heavily stepped toys when you are new. Never assume a suction cup alone makes an adequate anal-safe base; look at the actual shape and width of the base. If depth rather than width is what you are after, our guide to depth play deals with the bend past the rectum, which is a length problem and not a girth one.

Five steps, in order

1. Decide the use. Vaginal, anal, external pressure, or strap play. The base requirement changes with it.
2. Set a girth reference. Measure a toy you already use, or clean fingers as a rough stand-in. Record circumference if that is easier to picture.
3. Change one variable. More fullness, more depth, or a stronger curve: one at a time, not all three.
4. Read the widest insertable point. Not the tip, and not the base if the base is meant to stay outside.
5. Round down when it is close. On a first purchase, control is worth more than reaching a target.

Is there an average dildo size to go by?

We do not publish one, because we have no data we would stand behind. No survey of what beginners actually buy exists that we could cite, and a number invented for a blog post is worse than no number at all. An average also answers the wrong question. It describes a population; you are buying for one body.

The two numbers that do the work are yours: the widest circumference you already take comfortably, and the usable length you actually reach. Write both down before you open a product page and every size chart turns into a yes or a no instead of a guess. Most of the sizing emails we get arrive well after midnight, which probably says something about how this decision gets made. Having the numbers written down is what stops it getting made twice.

Four dildo sizes compared

These are four of our narrowest variants, all measured the same way. They are not four recommendations. They are four reference points, so you can see how far apart "small" can be inside one catalogue.

Read that table sideways and the point lands: the shortest one on the list is also the widest, and the longest is nearly the narrowest. A single size letter cannot carry both facts, which is why we publish all of them. An XS in one sculpture is not an XS in another. Recheck the live product page before ordering, and open the Oieffur Size Guide for every variant in centimetres and inches. For the design-side account of where those small numbers come from, we wrote up how we design the small sizes separately.

What else decides whether a size works

Firmness and shape change how big a size feels

Two toys with identical dimensions can feel very different. A firmer shaft resists compression, keeps its profile under pressure, and often feels more substantial. A softer toy, or one with a soft outer layer over a firm core, compresses at the surface and can feel more forgiving, although very soft designs need more guidance going in. Diameter feeds back into this: a thick section of the same silicone resists bending more than a thin section, which is why a brand's Soft or Medium label on its own can mislead. Read material, diameter, and construction together. Our Sensory Firmness Scale sets these out as plain physical comparisons.

Shape does as much work as size. A smooth taper introduces width gradually. A pronounced head, a knot, or stacked beads create a step you meet all at once, even when the listed maximum looks modest. Curves also direct pressure toward one area while straight shapes spread it. For a first purchase, a rounded tip and a gradual taper give you the most control. If sculpted detail is part of the appeal, read Your First Fantasy Dildo Guide once your size range is settled.

Common beginner sizing mistakes

• Buying for aspiration instead of current comfort. A toy is not a performance target.
• Comparing size labels across brands. Compare centimetres or inches, not Small versus Medium.
• Ignoring the maximum insertable diameter. A knot or a bead can be much wider than the shaft below it.
• Using total length as usable length. Bases and handles do not count toward insertion.
• Changing size, firmness, and shape at once. If the result is uncomfortable, you will not know which variable caused it.
• Treating pain as proof of progress. Stop, reset, add warm-up or lubricant, and choose a smaller step.

Lubricant, cleaning, and material checks

Use enough lubricant to reduce friction and reapply when needed. Water-based lubricant is the simplest compatibility choice for silicone toys. Some silicone lubricants can affect some silicone products, so check the maker's instructions and spot-test if the brand explicitly permits it. Oxfordshire Sexual Health's lubricant guidance likewise notes that water-based formulas are broadly compatible while some other formulas may degrade silicone.

Choose a nonporous, body-safe material from a maker that states what the product is made from, and wash the toy before and after use following its care instructions. If a toy is shared or moved between body areas, use a new condom or clean it fully first; Planned Parenthood's safer-sex guidance recommends exactly that. Inspect the surface before use and retire anything with a tear, a crack, a persistent odour, or a changed surface. Oieffur owners can follow the Care Guide for current cleaning and storage instructions.

Frequently asked questions

What size dildo should I start with?

One that matches a width you already take comfortably. If you have no reference, our narrowest variant sits at 10.8 cm (4.3 in) around and 10.7 cm (4.2 in) of usable length, which is a defensible starting anchor rather than a rule.

What size dildo is best for beginners?

There is no single answer, because girth, usable length, firmness, and shape all move independently. A gradual taper with a modest widest point is easier to learn on than a short, wide shape with an abrupt step, even when both are labelled XS.

Is a 6-inch dildo too big for a beginner?

Not necessarily. Six inches may be total length rather than insertable length, and girth may matter more than either. Check usable length, widest insertable diameter, firmness, and shape; you do not have to use the full length.

Is there an average dildo size?

Not one we will quote. We have no data we would stand behind, and choosing against a population average tells you nothing about your own comfortable width. Use your own two numbers instead.

How do I know when to size up?

Size up only when your current toy is consistently comfortable, you can use it without rushing warm-up, and you genuinely want more fullness. Move one step at a time. There is no benefit to advancing on a schedule.