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Breast related and other FAQs


Check out the other colours in the bra, still no luck, consider trying a sister size- so a 34D could try a 36C or a 32DD. The breast volume is approximately similar in sister sizes. Read more about the concept of sister sizing.

It might also be a good opportunity to just check you are wearing the right size- grab your tape measure and follow our UK bra size calculator and fitting guide.

Check out the other suggested products on the page or otherwise drop us an email to see when your favourite might be back in stock.

Fabrics tend to start losing their elasticity and support after around 30-40 washes. If you feel the support is faltering in your bra, just downgrade it for lower impact workouts or consider donating it to Smalls for All.

The overall fit should be snug but not too tight. It should not cut off your circulation or restrict your breathing. However, do remember that 80% of the support a bra gives your breasts should come from the underband.

Try jumping around a bit in your potential pick to make sure it is comfortable, the band stays in place and you are able to move freely. You should feel supported and secure. Jumping jacks are my test of choice, and GO BIG, give it your all.

If you need more information on bra fitting and checking your bra fit, have a look at our UK bra size calculator and fitting advice.

In theory, yes. However, it is not always as straightforward as that.

Depending on the brand and the amount of support offered, the sizing metrics may differ. Colour can even impact fit- often black fabrics have less give in them. This is why we are trying to bring you as many informative reviews as we can, starting with our own KL review.

Some brands or bras will be sized according to cup and band size, but some may use a scale from 0-8 such as the Enell sports bra or XS to XL+. Which means you’ll then have to convert your bra size to its corresponding XS to XL+ size. Thankfully, there is usually a size chart for this. 

If you need more information on bra fitting and checking your bra fit, have a look at our UK bra size calculator and fitting advice.

When unsupported, G cup breasts can bounce up to 14cm, and an A cup by 4cm! A sports bra is a technical piece of sports underwear that protects your breasts and reduces movement by up to 83%, whilst improving your performance and comfort during exercise!

With repeated uncontrolled bounce, the ligaments that anchor your breasts will stretch and the girls will start to sag.

If this was not enough, sports bras are less likely to chafe, are designed from moisture wicking fabrics so much less likely to get smelly and you won’t get that annoying strap slippage mid workout.

Read our blog post on why you should wear a sports bra.

Medium support, high support, low impact, extreme control, ultimate control… what does it all mean and how do they compare?

The problem is two-fold. Firstly, manufacturers all describe their bras differently in the terms they use- so ‘high impact’ may be the same as ‘ultimate control’ from another brand.

Secondly, the bounce impact of a sport or activity will vary according to your breast size and shape. You just can’t argue with the laws of physics: bigger breasts and those with a narrower top portion will naturally need more support.

This is why at KnockerLocker we have developed the Power Rating. This aims to take into account breast size to give you a more accurate idea of the type of bra that will give you and your breasts the right support for your chosen sport.

Check out the full power rating guide.

A low impact sport would be something like yoga, rowing, golf or pilates.

Medium would be power walking, gym work (step machine/ crosstrainers), weight training, cycling.

High impact would be running, racquet sports, equestrian, aerobics.

Combining this impact level with your breast size gives us our KnockerLocker Power Rating– a great guide as to what bra will work for you and your chosen sport.

Woman with round breast shape wearing freya sonic bra

About KnockerLocker

KnockerLocker is partnering with the Pink Ribbon Foundation, donating to the charity 5% of the price you pay for every bra sold from the KnockerLocker purse.

We are also offering you the option to make your own donation, helping us to help Pink Ribbon.

Every 10 minutes a woman in the UK is diagnosed with breast cancer and it claims the lives of around 12 000 women each year- this is something none of us can ignore.

Find out more about their work here.

Smalls for All collect underwear for women and children in need. In Africa, they help those living in orphanages, slums, IDP (internally displaced persons) camps and schools, as well as those in hospitals suffering from medical conditions like obstetric fistula.

The charity operates from the UK and supports people and charitable organisations working on projects in Africa who are able to transport and distribute the pants and bras collected. They also help charities that focus on alleviating poverty in the UK by providing them with underwear.

KnockerLocker asks that you consider adding in any of your preloved bras or donations of new pants with any items you are returning to us. We will then add them into our pile of pants to be sent onto Smalls for All.

We also donate any unsaleable returned sports bras to the charity, rather than into landfill as happens with many online retailers.

KnockerLocker is always looking to lend their support to women in sport- whether you are running a marathon, climbing a mountain or organising a sporting event please do get in touch to see if we can help you out with some kit.

YESSSSSS. KnockerLocker is actively working towards a more sustainable future.

We have chosen to use 100% composable, reusable mailing bags. The shipping labels and stickers are made from recycled paper. You can either: reuse the bag, put the bag in your home compost (remove the labels first), or if you do put it in landfill, it will degrade and feed the worms.

We are encouraging shoppers to adopt a considerate shopping method and only purchase what would really hope to keep, rather than filling the cart with items for a home dress-up session, anticipating returning the larger portion of them. This approach effectively doubles the carbon footprint of online shopping.

Some ecommerce stores consign a lot of returned items to landfill; however, any items returned to us deemed unsaleable are up-cycled to Smalls for All.

Noissue Eco Alliance

Delivery & Returns

Standard delivery is £4.50 and is sent by Royal Mail Tracked 48hr. We aim to dispatch all orders on the day or day after receipt.

So you can’t wait? Express delivery costs £6.50 and is sent by Royal Mail Tracked 24hr. These items are usually delivered the next working day. Express orders are always packed as a priority.

Returns are indeed free! Drop us an email to initiate and we will have your usual Royal Mail postie pick the item up the next day. 

No need to print a label- they will bring it with them.

Currently just mainland UK and Ireland.