Buying running shoes online starts with checking your foot measurements, the exact model's fit and the seller's return terms. Treat length, width and toe-box shape as separate decisions. Use your existing shoes as a reference, then try the new pair indoors before committing to outdoor miles.

1. Check Your Measurements Before Choosing a Size

Start with the shoes you already own. Write down the model, version, size and width of the pair that fits you best. Also note anything you would change: cramped toes, a loose heel or pressure across the top of your foot.

Then measure both feet using the instructions on the brand's size chart. Compare those measurements with that brand's chart, rather than relying on a conversion you found for a different manufacturer. Check whether the chart refers to foot length or another measurement before choosing a size.

Pay attention to US, UK and EU labels, especially when ordering internationally. A men's US 11.5 and a UK 11.5 are different sizes. Unisex listings need another look, too: confirm which sizing system the product uses.

Brooks' official sizing guide recommends approximately a thumb's width of space in front of the longest toe. Use that as a fit check alongside the instructions for your chosen model. You should also assess heel security and pressure around the rest of your foot.

Don't automatically add half a size to every order. First establish what your current size means, what the manufacturer recommends and where your existing shoe feels too small.

2. Separate Shoe Length, Width and Toe-Box Shape

A shoe can be long enough and still squeeze the sides of your foot. It can also have a roomy toe box but feel tight through the midfoot. Those are different fit problems.

Width letters also need context. In Brooks' US sizing, men's D is medium and 2E is wide; women's B is medium and D is wide. Its width guide explains the options. Check the selected product's chart rather than assuming every listing uses identical labels.

My tennis-shoe experience illustrates why length alone isn't the answer. In the K-Swiss Hypercourt Express 2, a size 12 regular still felt snug, while a 12 wide worked. That isn't a running-shoe recommendation; it's a reminder to identify the source of the pressure before simply ordering a longer shoe.

3. Research the Exact Model and Match It to Your Use

Search for the full model name and version number. A review of last year's shoe may help with background, but don't assume the latest version uses the same upper, cushioning or fit.

Read for specific observations rather than star ratings alone. A reviewer who explains that the heel fits securely but the midfoot feels shallow gives you more useful information than someone who simply calls the shoe comfortable.

What does “true to size” mean in that review?

Look for the reviewer's comparison point. Their usual dress-shoe size may differ from their normal running-shoe size. Their foot shape and sock choice may differ from yours, too.

For a firsthand example, my Topo Ultraventure 4 review explains why I needed to size up. My use was primarily walking, so it shouldn't be read as proof of how the shoe fits everyone during running.

Does the shoe suit the activity you actually do?

Decide whether you're buying for road running, trails, walking or a mixture. Also consider whether you want a flexible feel or more structure. The right size won't turn a shoe designed for one purpose into the right choice for every workout.

Our running shoes guide for everyday runners helps narrow down the category. Individual reviews then explain how those shoes were used. My Altra Escalante 4 review, for example, covers walking, treadmill and gym use rather than outdoor running mileage.

4. Compare the Total Cost and Return Terms

Check returns before checkout. A low sale price loses some of its appeal if you can't exchange the size or returning it costs more than expected.

Look at the actual seller, particularly on a marketplace. Confirm who supplies the shoes, which return terms apply and whether your selected size or color is marked final sale.

Illustrative example: A $90 pair plus $10 delivery and a $15 return fee would cost $25 if you returned it and the delivery charge was nonrefundable. A $110 pair with free delivery and eligible free returns would cost more to keep, but less to send back. These are hypothetical figures, not current retailer prices.

Indoor try-ons and wear trials are different

A normal return window doesn't necessarily let you run outdoors in the shoes. Read the condition requirements and check when the deadline starts.

As one current US example, Topo's direct-store return policy offers a 30-day trial for running shoes, excludes final-sale items and applies conditions to shipping refunds and return postage. Its support guidance says the trial applies to purchases from topoathletic.com. Don't assume an order from another seller carries those same terms.

Buying two sizes can help if you can manage the temporary cost and both pairs qualify for return. Check those details first, then set a reminder comfortably before the deadline.

5. Use an Indoor Fit Checklist Before Keeping the Shoes

Try both shoes with the socks you plan to wear. If you normally use an insert, check the fit with that setup as well. Keep packaging and tags until you understand the return requirements.

1. Check toe clearance. Stand up and assess space in front of your longest toe using the brand's guidance.
2. Check width. Your forefoot shouldn't feel squeezed against the sides.
3. Check the midfoot. Notice pressure across the instep or arch before tightening the laces further.
4. Check the heel. Walk on a clean indoor surface and notice rubbing or excessive lifting.
5. Check both feet. A good fit on one side doesn't settle the decision.
6. Move beyond standing still. Try normal walking and any additional movement the return policy permits. Don't begin an outdoor test unless it is allowed.

An indoor check can't fully predict a long run, but it can reveal an obvious mismatch. Don't rely on break-in to fix toe compression, persistent pressure or a heel you can't secure comfortably.

Keep a quick fit record after each purchase: model, version, size, width, socks and what worked. It will give you a better starting point for the next order than trying to remember whether an entire brand “runs small.”

6. Questions About Buying Running Shoes Online

Should I buy running shoes half a size bigger?

Sometimes, but don't apply that rule automatically. Use the exact brand's measurements and fit advice, then check toe clearance and heel security. A dress-shoe size and a running-shoe size aren't necessarily the same reference.

Should I size up or choose a wide running shoe?

If the length is suitable but the sides squeeze, investigate a wider version or a different shape. If the shoe is too short, consider more length. Some feet need both, which is why changing just one number may not solve the problem.

Does a wide toe box mean the whole shoe is wide?

No. Toe-box shape describes the front of the shoe. The heel, midfoot and internal volume can still feel relatively close. Check width availability and model-specific fit notes separately.

Can I return running shoes after wearing them outside?

Only if the seller's policy permits it. Some sellers require shoes to remain unworn; others offer a defined wear trial. Check your seller, country, deadline and final-sale exclusions before the first outdoor session.

Is it worth ordering two sizes?

It can be useful when the likely fit is unclear, the temporary cost is manageable and returns are permitted. Compare both indoors with the same socks. Return the unsuitable pair promptly rather than treating the deadline as a target.

My advice: Choose the shoe category first, check length and width separately, then protect your purchase with clear return terms. You don't need to predict the fit perfectly. You need enough information to make a sensible choice and a practical way to change it if it doesn't work.