Did you know Kate Middleton wears shoes in two different sizes?

The Duchess of Cambridge's shoe collection is the envy of many, that's for sure - but did you know she has a nifty fashion hack when it comes to her footwear? She buys her heels in two different sizes, between a 38.5 and a 39 (or a 5.5 and a 6 in British sizing). No doubt Kate does this for comfort reasons and it seems to vary depending on the brand - her Jimmy Choo 'Georgia' navy pumps and her red carpet 'Vamp' strappy sandals are in a 38.5. She even goes down to a size 38 in Rupert Sanderson designs - the brand advises sizing down on its website.

Kate's Jimmy Choo 'Vamp' sandals, in a size 38.5

Meanwhile, Kate wears a 39 in her L.K. Bennett 'Agata' sandals, which feature a peep toe and a bow detail at the ankle. It may be that the Duchess opts to go for a size bigger in her strappy heels since she might be more likely to wear them in the warmer months, and no one wants their feet swelling during a royal engagement, right?

MORE: Royal ladies wearing frothy fairytale gowns - all the stunning pictures

Kate isn't the only royal woman who's savvy when it comes to her shoe sizing, in fact. The Duchess of Sussex is actually thought to wear her favourite heels a whole size larger than necessary - in order to avoid discomfort. Look closely at pictures of Meghan at official events, and her shoes often appear too big for her, with a gap at the heel. 

Meghan's Aquazzura Matilde heels

HELLO!'s fashion editor Rachel Story tells us that it's not uncommon for stars to do this, too. "Celebrities often size up for red carpets or other events - mainly to avoid blisters," she says. "Plus, it's all about how the shoes feel when you try them on and walk around in them, rather than sticking to what size you normally take. Italian shoes often run bigger - I always take a half size smaller. So that could be the case for why some styles, such as Aquazzura, are large on Meghan." 

Kate's Jimmy Choo 'Georgia' navy pumps

The black court shoes Meghan chose for her Royal Ascot debut in June 2018 appeared to be a little too big for her, as did her Aquazzura Matilde heels when she and Prince Harry first announced their engagement in November 2017.

WATCH: more royal fashion hacks

And if you're wondering how Meghan and Kate manage to walk in heels that are a little too roomy, there's apparently an extra red carpet hack. "Some stars have been known to stuff the toe with padding like cotton wool," Rachel says. "And then it can be taken out if you feel you need a bit more room."

MORE: The moving way Princess Margaret inspired her daughter Lady Sarah Chatto's elegant style