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Will It Fit?

Will it fit? Let's find out, gently.

Measure a toy, add a little about you, and watch a clear read take shape. You get honest guidance on lube, warm-up, and working your way up, built for safety and never explicit. Nothing you enter leaves your device.

Until you add your own sizes, the read uses (about 3.8 cm across vaginally, 3.2 cm anally): a starting point, never a limit. Add your comfortable size in and it tunes to you.

Where does it go?

Guidance adapts to the anatomy you pick.

Units
Girth measured as

Measure the object

Drag the dials, scroll, or type. Girth matters more than length.

Girth (across)
the widest part
Insertable length
only what goes in

You (optional)

Everyone's built differently. These personalise your result and stay on your device.

Your size history

on this device only

Log girths that felt good. Your largest becomes the baseline the planner steps up from.

Nothing saved yet. Add girths you already know feel comfortable, and the planner will use your largest as a safe starting point.

cm
loading…
comfortable openingthe object
Awaiting measurements.
Waiting for measurements

Enter a girth to begin

Add the object's diameter or circumference above and your result will appear here, live.

Good things to know

You control how deep something goes simply by not pushing it all the way in, so length is rarely the limiting factor. Girth is different. The opening has to stretch around the whole width at once. That is why a shorter, thicker object can feel far more intense than a long, slim one.
Until you log a size that felt good, the read compares the object's girth to a conservative general reference: vaginally, roughly the average erect penis girth(a review of up to 15,521 men put mean erect circumference near 11.7 cm, about 3.7 cm across); anally, a lower figure, since that tissue is more delicate and doesn't self-lubricate. Warm-up and lube nudge the range up a little. The moment you save a girth you've comfortably taken, that becomes your personal baseline and the averages step aside. They are references, never limits. See the sources below.
The easiest reference is something you have already used comfortably. Measure its widest diameter straight across, or wrap a soft tape around it for circumference, and log that in your size history. If you are starting fresh, a single clean finger is a gentle place to begin.
Water-based lube is the safe all-rounder and works with every toy material. Silicone lube lasts longer and is great for anal, but keep it away from silicone toys, since it can degrade them. Avoid oils with latex condoms. Whatever you choose, use more than you think you need, and reapply.
The anus does not self-lubricate, so lube is not optional. The sphincter is a muscle that needs time to relax, and the rectum curves, so go slow and let your body open at its own pace. Always use a toy with a flared base so it cannot slip fully inside, which is a genuine emergency-room risk otherwise.
Patiently. Warm up, use lube, and stop while it still feels good rather than pushing to a limit. Staying comfortable at one size across several sessions is what lets the next size up feel easy. There is no prize for rushing, and going too fast is how tissue gets torn.
Stop for sharp pain, and never push through it. See a healthcare provider for bleeding beyond a spot or two, pain that lingers for days, trouble controlling bladder or bowels, or anything that got stuck. These conversations are routine for clinicians.

Sources & further reading

The guidance and reference numbers here lean on reputable, current medical and sexual-health sources rather than folklore. A few of the main ones, if you'd like to read further:

Consumer-health and clinical pages are summarised for plain language; follow the links for the full detail. Nothing here replaces advice from your own healthcare provider.