Prom Dress Alterations: How to Get the Perfect Fit

Ask any girl what she wants from her prom dress and she'll say the same thing: she wants it to fit perfectly. Which is completely reasonable. What's less simple is agreeing on what ‘perfectly’ actually means - because after fitting around a thousand dresses this season at Lily's, we can tell you that it's different for almost every girl who walks through our door.

Before you book your prom appointment, here's everything we think you need to know about how fittings and alterations actually work - and what to expect at every stage.

What does the ‘perfect fit’ actually mean? 

There are two technical non-negotiables: straps shouldn't be slipping off shoulders and it needs to fit properly across the boobs. That's it. Everything else is personal.

Some girls want a dress so fitted that everyone in the room holds their breath along with her. Others want to be able to breathe, dance and eat their body weight in buffet food without thinking about their dress once. Both are completely fine and neither is more right than the other. The job of a good fitting is to work out which version of perfect your daughter is after - and then get her there.

It helps to have that conversation before the appointment rather than during it. If she knows what she wants and can tell the team clearly, the whole process is faster and the alterations are more targeted. Is she after that second-skin feeling, or does she want to feel comfortable and free? Either way, we're working towards the same goal: a dress that feels like it was made for her.

The other definition of ‘perfect fit’: what mum thinks!

Here's the bit we don't always talk about publicly, but probably should: sometimes the tension in the fitting room isn't between the girl and the dress. It's between the girl and her mum.

Girls often start dress shopping at 15, when parents have the final say. They come back for fittings at 16 having developed a very clear sense of their own mind - and occasionally, those two versions of the same person want different things. We've seen it enough times to know it's worth at least considering early on.

Earlier this year, a girl chose a slinky black dress with a high leg split. Her mum wasn't keen on the split and had it stitched up before the May fitting. When her daughter came back and saw what had been done, she was - understandably - not happy. We sat mum down with a cup of tea and gently made the case: it's her dress, it's her night, and she should wear it the way she wants to. The stitching came out, the split went back in, and everyone left feeling a lot happier about things. 

We're not saying parents don't get a say - of course they do. But the girl's voice needs to be part of the conversation from the very beginning. Disagreements aren’t dealt with early have a way of coming back at the worst possible moment.

What if she changes her mind?

This is the question we hear most often from parents, particularly those whose daughters are booking their own appointments - something we're seeing a lot more of, with mums encouraging their daughters to take the lead. What if she changes size? What if she goes off the dress entirely?

Even based on the numbers we’ve seen this season alone, it’s a rarity. Out of roughly 1,000 dresses sold, around 10 girls changed size. Two changed their dress completely. That's it.

We don't offer a dress-swap service, and this is exactly why - it would mean extra appointments and added pressure to solve a problem that affects fewer than 1% of our customers. We did have one girl who came back at her fitting in tears over a big pink ballgown she'd chosen at 15 - a choice that, on reflection, had been more her mum's than hers. She had a photo on her phone of what she actually wanted: a slim blue dress with a leg split. Her mum listened, they swapped, and that was one of only two style changes out of a thousand dresses. It happens - but rarely enough that it shouldn't put anyone off ordering early.

The alterations timeline: when fittings happen and why

This is where the timeline matters and it's worth understanding before you start planning.

Dresses ordered early in the season typically arrive with us around May, ahead of proms in late June and early July. When a dress comes in, your daughter will have a first try-on so we can see how it sits and what, if anything, needs attention. But the final alterations - the ones that really pin everything in place - happen 3 to 4 weeks before prom, not months out.

That's a deliberate choice. Girls change over the course of a year. Height, shape, how they want the dress to feel - all of it can shift between October and June, and leaving the finishing touches as late as sensibly possible means the dress fits the girl she is on the night, not the girl she was when she first tried it on. If you want to read more about what types of alterations are most common, our earlier guide to prom dress alterations covers it in more detail.

Alterations at Lily's are competitively priced - please ask our team for current pricing when you book your appointment, and factor a contingency into the overall prom budget from the start rather than treating it as a surprise at the end.

What to bring to the fitting

Everything. Shoes, underwear, jewellery, accessories - the lot. If doing hair and makeup helps your daughter feel more like herself, encourage her to do that too. Plenty of girls arrive with their lashes on and their nails done, and it makes a real difference to how the appointment goes.

It’s not complicated: a dress looks and feels different depending on whether you feel pulled together or not. A girl who arrives in her school uniform and bare feet is judging a very different version of the dress to the one she'll be wearing on prom night. Seeing something close to the finished picture - the right shoes, the right underwear, feeling her best - helps her make better decisions and feel more settled in the ones she's already made.

And if anything feels off on the day, it needs saying out loud. Small tweaks are easy when there's time. Staying quiet and hoping for the best is how prom-night disappointment happens (and none of us are here for that). 

One last thing

The fitting process exists for one reason: so your daughter walks into prom feeling incredible, not just in the boutique on the day she said yes to the dress. Encourage her to be honest with her consultant, bring everything she needs, and trust that if something isn't quite right, we'll sort it.

Ready to get started? Browse our prom collection and book your appointment at Lily's - we've got over 4,500 dresses in stock and we can't wait to help her find the one.