'Want the perfect blue, straight-leg jeans? These are the best ones out there.'

It's not easy, finding the perfect pair of jeans.

I have struggled with this plight for most of my adult life, navigating changing leg lengths, waist heights, silhouettes and washes.

I have cycled jeans in and out of my wardrobe. I've relegated pairs to the back of my drawers, gathering dust in some kind of sad denim purgatory.

Watch: Mamamia tries 'Style Maths' with Em Vernem and Basmah Qazi. Post continues below.

I've mercilessly thrown out my once-loved jeans, mocking them for their whiskers or the cuffed hems I never got tailored.

"Why did I ever buy those?" I've asked myself time and time again, thinking about the thousands of dollars I've wasted in the process.

We can never truly rest. There is always a new style around the corner, waiting to make us feel less-than in our jeans. I should know — I've tried them all.

I'm forever searching for the perfect blue jeans. Images: Supplied.

But after almost two decades writing about fashion and circling back to this hot-topic — The Holy Grail denim — one pair has stuck around: The blue straight-leg jean.

This style has a legacy. It's the original jean, going right back to when the prototype for denim pants with rivets was patented by Levi Strauss and Jacob Davis in 1873.

It makes sense that out of all the trending denim styles that have evolved since, the classic Levi's silhouette still feels the most enduring.

Fashionable celebrities throughout history have turned and returned to versions of the iconic cut, from Marilyn Monroe to Princess Diana — and these days they remain the go-to style for It-girls like Alexa Chung, Kaia Gerber and Kendall Jenner.

They never get old.

Princess Diana wears Levi's straight-leg jeans. Image: Getty.

So if you're finding yourself on an endless quest for denim, it might be worth going back to the beginning, and opting for a pair of blue straight-leg jeans that won't look dated in one, five or 10 years' time.

Alexa Chung wears blue straight-leg jeans with a Valentino outfit. Image: Instagram/alexachung

There are a couple of things I think you should look for in any pair you want years of mileage out of:

• A mid to high-rise waist — you don't want anything going on around your waistline that's going to hallmark the *exact* year your jeans were trendy.

• A hemline that crops just on the ankle for maximum styling potential.

• A firm denim that'll hold its shape through lots of wash and wear.

Remember — we're hunting for classics here, people!

But where to find them?

Here are my favourite straight-leg blue jeans for every body and budget.

Levi's 501 Original Jeans, $159.95.

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Levi's 501's are the original and the best, IMHO.

Wrangler Claudia Hi Straight Jeans, $159.95.

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I'm obsessed with the combination of the mid-blue colour and rigid denim. These can be dressed up or down so easily.

Peachay Olivia Jean light blue, $240.

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Peachay designs their jeans for people with smaller waists and bums, so if you're always struggling with the fit around your hips, they're worth the investment.

Levi's Ribcage Straight Ankle Jeans, $159.95.

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Nothing To Wear host Leigh Campbell swear by Levi's' 'Ribcage' style as her go-to jean, and has them in several washes.

Commonry The High Rise Girlfriend Jean, $119.95.

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Offering inclusive sizing, Commonry is making some of the best classic denim around. The cut of these is flawless.

City Chic Harley Lora Wide Leg Jean, $119.95.

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If you're looking for more of a flare at the ankle, these are my pick for a mid-rise option.

Assembly Label Vintage Straight Jeans.

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This Aussie brand is all about chic no-frills denim, and their straight-leg jeans are fast becoming a cult buy.

Lee High Straight Crop Jeans, $159.95.

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We're not breaking any moulds here - another pair of easy-to-wear, straight blue jeans with just the right ankle length.

Cotton On Original Straight Jean, $59.99.

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With a more relaxed fit and vintage-inspired wash, this affordable style ticks all the boxes.

Atmos & Here Milla Straight Leg Jeans.

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These come in six colours so you know they're popular, but I love the mid-blue tone. Keep in mind they might be more on the cropped side if you're tall.

Ceres Life Frankie Loose Straight Jean.

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If you like your fit a bit looser and your hemlines a little longer, this option from local brand Ceres Life might be your pick.

Do you have a denim dilemma you want us to look into? Share your thoughts in the comments.

Feature image: Supplied/Peachay.