Nobody wants to stop sex to hitch a harness back up their arse.
The dildo tends to get all the attention when you're shopping. Fair enough. But the harness is what holds it against your body, so give the straps and fit a proper look too. You want it to stay put when you move, feel comfortable and hold the dildo you've chosen.
Looking fucking good in it is a perfectly reasonable extra.
Adjustable straps or pull-on briefs?
A jock-style harness usually has a waist or hip strap, two leg straps and a front ring or panel for the dildo. You adjust the straps separately, so you can tighten the waist without squeezing your thighs, or loosen one leg strap without loosening the whole harness.
If you like straps across bare hips and an open view of your arse, this can be a good place to start. Add your favourite bra or wear the harness on its own. Straps across bare skin don't need much help to look kinky.
Brief-style harnesses pull on like underwear, with a front opening to hold the toy. There's more fabric and usually less adjusting to do. They can suit someone who wants to pull the harness on and get going without fastening several straps first.
Choose briefs that fit closely enough to keep the front steady. Baggy might be lovely for Sunday-morning undies; it's less useful when the fabric is meant to hold a dildo in place.
Fit the harness to your hips and thighs
Measure around the place you'll wear the waist or hip strap. If the harness has leg straps, measure your upper thighs too. Use those measurements to choose your size. Buying the smaller one and hoping for the best is an excellent way to spend the night swearing at a buckle.
Once it's on, sit down, bend and move your hips. The front should stay steady, and you should be able to move without a strap digging in. Adjust one strap at a time so you can tell what's helping.
Pay attention to where the buckles land. One can feel fine while you're standing and bloody annoying when you sit on the bed. Better to find that out while you're trying it on than while your partner is wondering why you've suddenly stopped.
Loosen or stop if you get pinching or numbness. A harness that hurts isn't a good fit, however hot it looked in the mirror.
Make sure the dildo fits the ring
For a typical O-ring harness, the dildo's shaft goes through the ring and the wider base stays behind it. The ring holds the toy near its base, and the base stops it pulling through.
Match the ring opening to the width of the shaft where it sits. A roomy ring around a thin dildo can leave it wobbling about. A ring that's too small won't accept the toy properly. Neither problem improves because you're keen to get naked.
Some harnesses have rings you can swap for different sizes. Others have a fixed opening or another way of fastening the dildo. If you want to use several compatible toys, removable rings give you more choice. They still need to hold each toy securely.
A set with the harness and dildo included can simplify the first purchase. Our strap-on dildos and sets give you both individual toys and sets to browse. Choose an included dildo you'd actually enjoy using, rather than buying the set purely to avoid thinking about sizes.
Pick a dildo you both want to use
You've chosen the harness. Now you're eyeing off a much bigger dildo, because apparently buying one new thing has made you ambitious.
A longer or heavier toy gives the harness more to hold and can change how it sits against you. The size also needs to suit the person receiving it. Ask what they fancy before arriving with a surprise they have to politely talk their way out of.
Our dildo size guide explains the measurements. Bigger can wait until bigger is something you actually want. There's plenty of fun to have with a dildo that doesn't make either of you say, “Jesus, where's that meant to go?”
Try the harness on before sex
Fit the toy, adjust the straps and move around in it. Learn which buckle loosens which strap while you've got the light on and enough patience to give a shit.
Your partner can help with the fit if you want them to. Having them straighten a strap against your hip can be part of getting ready together. Spending ten minutes arguing over which way a buckle goes is less appealing, so sort out the basics first.
If it keeps slipping, our slipping harness guide helps you find the cause. If you're new to the whole thing, the strap-on beginner's guide covers getting started.
Then take another look in the mirror. A harness you fancy yourself in, a dildo you want to use and straps that stay where you put them. That's a much better start than spending half the night pulling your gear back up.