How to Alter a Swimsuit That is Too Big or Small (Easy Tips)

If you’ve bought a fancy new swimsuit only to find it doesn’t fit, don’t panic. If you’re at all handy with a needle and thread, it shouldn’t be too much off a drama to turn that ill-fitting piece into a flattering dream.

Can You Alter Swimsuit Bottoms?


Although swimsuit material has a reputation for being difficult to work with, it doesn't take too long to master - and unless you're planning on a complete restructure, any modifications you make to your swimsuit, whether that's altering a strap, bringing its size down (or even up) a notch, or adjusting the legs, shouldn't take you too much effort or time at all.

Some of the reasons you might want to alter a swimsuit include:

It’s too big - Maybe you’ve lost weight recently. Maybe you couldn’t resist that big discount despite the swimsuit being two sizes too big. Whatever the reason, a swimsuit that’s too big is just as unflattering as one that’s too small… and comes with certain additional ‘risks’ that could spell disaster for your modesty.

Downsizing a swimsuit isn’t too challenging, providing you don’t want to reduce it by more than a dress size. Just bear in mind that if your swimsuit is too big as a result of having lost its stretch (an all-too common problem with old swimsuits that’ve seen more than just a few summer’s action), making any alterations to either size or fit might be difficult.

It’s too small - A swimsuit that’s too large can be unsightly. A swimsuit that’s too small can be positively painful. If you’ve lost weight or bought a swimsuit that doesn’t quite seem to know what to do with your curves, you’re not entirely out of luck. Although swimsuits can’t be ‘let out’ in the way of garments that have a built-in seam allowance, they can be made a little roomier with the addition of some strategic panels.

It’s too boring - If you’ve been wearing the same swimsuit for several seasons, you’re probably feeling in need of a change. Providing you know your way around a sewing kit, you shouldn’t find a few modifications too hard to master. Maybe you want to change your two-piece into a one-piece. Perhaps you want to turn a high-waisted pair of bottoms into a low waisted pair (or vice-versa)? Whatever the problem, it’s won’t be too hard to find a solution.

How to Alter Swimsuit Bottoms


Altering swimsuit bottoms isn’t too challenging (although if you’ve not worked with a super-stretchy material like swimsuit fabric before, it may take a little getting used to) but before you start, you’ll need to set your expectations.

Downsizing by one size is realistic. Expecting to turn a size 20 swimsuit into a size 0 isn’t. Similarly, sizing up a swimsuit will usually require the addition of some strategically placed panels. While this can look perfectly lovely, it is likely to change the style of the swimsuit by at least some degree - unless you manage to find panel material in exactly the same material and hue as the swimsuit you’re altering, of course.

But providing you’re realistic, and providing you know your way around a needle and thread, altering swimsuit bottoms can be done easily enough at home.

How to Alter a Swimsuit That is Too Big

If you’ve found yourself at the mercy of a swimsuit that’s just a little too big for comfort, don’t consign it to the donation box just yet. Adjusting the ties or sewing up any loose areas around the waistband and leg holes should soon have it fitting like a dream. Just bear in mind that due to the nature of swimsuit material, any adjustments made by sewing might be a visible, so always try modifying by the ties first.

The Method

  • Step 1 - Try on the swimsuit. Make sure you’re not wearing any underwear at this stage, as it could give a false impression of size and fit.
  • Step 2 - If the swimsuit comes with straps, adjust them to see how much of a difference these can make to the overall fit. Make a note of any areas around the bottoms that are gapping or sagging (usually this will be along the leg openings, seat, and waist), then gather the elastic seam at the waist or legs (or both, depending on where the gaps are) and pin to fit.
  • Step 3 - Take the swimsuit off and fold the areas you’ve marked with a pin. Double stich the folds in place by hand.
  • Step 4 - Try the suit on again to check the new fit. If it’s still too large, repeat the above steps until you achieve the perfect fit.

How to Alter a Swimsuit That is Too Small


Unless your swimsuit is old enough to have started to sag, it’s almost impossible to make it bigger. Unlike other garments that come with an inbuilt seam allowance that can be ‘let out’, swimsuits have next to no excess fabric. If you want to make yours bigger, you’re going to need to get creative – and that means getting friendly with the concept of panels.

Panels might change the style or design of a swimsuit, but this isn’t neccesarily a bad thing - not if it’s done wisely, in any case. Sheer or lace panels can look lovely, adding plenty of style and personalization to a suit…. and, of course, a little more ‘breathing room’!

You’ll need to select a fabric with the same amount of stretch as the swimsuit (either 2-way or 4-way) but other than that, you can get as adventurous (or as subtle) as you like in your choice of panel material.

To add a panel, simply cut out a length of fabric to the required size. Cut along the swimsuit seam, pin the panel in place, and sew. To avoid any unsightly puckers, pay careful attention to how you stitch the seam between the panel and the swimsuit. And that’s it – a few extra inches of comfort and with almost no effort at all.

How to Alter Swimsuit Straps

An ill-fitting strap can (sometimes quite literally) let down your entire swimsuit, leaving you with poor support, a saggy bottom, and the constant need to yank your swimsuit up… which, regardless of how you look at it, is never a good look. Fortunately, making a few modifications to a strap is relatively easy.

If your swimsuit comes with a shoulder seam, try this easy method to put things right.

The Method

  • Step 1 - Using a seam ripper, gently remove the shoulder seams.
  • Step 2 - Put the suit on to check for fit. Play around with the straps until you land on the best fit. Pin the straps in place. Sit down while still wearing the suit to make sure the shortened straps are still comfortable and don’t dig in at the shoulders.
  • Step 3 - Sew one strap together with a straight seam. Flatten the seam allowances and sew around a 1/4 inch from the seam on each side to keep the seam allowances lying flat. Repeat the same on the other strap.
  • Step 4 - Cut away any excess fabric and finish with a zigzag stitch.

Altering Swimsuit Legs

If the overall look of your swimsuit is being let down by awkward leg openings, a few alterations should soon have things looking hunky-dory. But before grabbing your sewing supplies, it’s worth working out exactly what needs to be altered. Sometimes, it won’t always be the leg itself that needs to be altered.

Try the swimsuit on for size and take a close look at where the problem is. It could very well be that the leg opening is at fault, but equally, the poor fit could be down to the sides not being snug enough or even the sides not rising high enough.

Too Wide at the Front

Are your bikini bottoms wrinkling in vertical stripes at the front? Are the legs chaffing your inside thighs? Then it could very well be the case that your bottoms are simply too wide across the front. Altering the leg may be the obvious way of reducing the chaffing, but you’ll also need to look at reducing the overall width of the bottoms.

Too Baggy at the Front

Suffering from horizontal wrinkles along the front of your swimsuit bottoms? Gaping along the inner thigh? Are you constantly having to tug the bottoms back in place after every dip? Then it sounds like your bikini bottoms are just plain too big for you. Changing the leg will help, but you’ll need to consider reducing the overall size if you want the perfect fit.

Too Long at the Groin

If your swimsuit bottoms look too big, too wide, and are constantly on the verge of dragging down or coming off completely after you’ve taken a swim, it’s likely they’re too long in the groin area.

Too Big across the Back

Whether your swimsuit is a one piece or a two piece, any bunching around the back indicates there’s too much fabric at the rear. If you want to modify the fit, you’ll need to remove the excess fabric as well as modifying the leg holes.

Too Baggy at the Back

If there’s a significant gap between your swimsuit legs and the back of your own legs, along with an excess of fabric at the back, you’ll likely know how hard it is to keep the bottoms in place once they’re wet. Adjusting the legs might be needed, but ultimately, you’ll need to reduce the overall size if you want a good fit.

Altering Swimsuit Legs

If it’s definitely the swimsuit legs that need adjustment, and not the overall size of the bottoms, adjusting their fit is easy enough.

Nine times out of ten, the problem is likely to caused by the legs finishing at an awkward place. If this is the case, you’ll simply need to hem them to end just above your hip bone. Simple fold the material to the desired length, pin, then sew in place.

Once you’re done, you should find that not only is the fit more comfortable, your legs look instantly longer and slimmer. What more could you want from a swimsuit?

Can Tailors Alter Swimsuits?

Making certain alterations to a swimsuit are easy enough, but there’s no shame in admitting when you’re beat, especially when you’re dealing with swimsuit material (a notoriously challenging fabric that can make even the most experienced home seamstress cringe).

If you have a tailor you trust, a particularly difficult modification to make, or maybe just no time and even less patience, calling in the professionals is absolutely fine – and in fact, sometimes even recommended.

How Much Does it Cost to Alter a Swimsuit?


If the thought of modifying your own swimsuit is too much, getting a professional to do the hard work for you can be a good call… just be prepared to pay.

Actual costs will depend on just what kind of modifications are needed, along with whether or not the swimsuit has a liner - in which case, the liner will need to be adjusted separately to the swimsuit, and will add several dollars onto the final bill.

Minor adjustments like altering straps won’t result in a big bill, and shouldn’t cost more than around $10 dollars or so. If you need any major alterations, such as restructuring the bodice or changing the style, size, and fit entirely, expect to pay anything up to around $60 dollars… which in some cases, might be significantly more than the cost of the swimsuit alone.

Always ask for an upfront indication of costs before proceeding – unless the swimsuit is particularly precious, you might find it’s cheaper to just buy a new one.

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