What Size Running Shoes Should I Get? A Beginner's Fit Guide

Most people should get running shoes about a half size larger than their everyday shoes, with roughly a thumb's width of space between the longest toe and the front of the shoe. Fit the larger of your two feet, try shoes on late in the day in running socks, and check width as carefully as length: if a shoe pinches across the ball of your foot, the fix is often a wide version, not a bigger size. Each point below is sourced to fit guides from Running Warehouse, ASICS, Harvard Health, Cleveland Clinic or the AAOS.

Running shoe size guide at a glance

How to measure your feet at home

Running Warehouse's fit guide describes the tracing method; the rest is simple measuring. You need a sheet of paper, a pen and a ruler:

1. Put the paper on a hard, flat floor, not carpet.
2. Stand with one foot firmly on the paper, keeping your weight evenly balanced.
3. Trace a thin line around your foot, holding the pen straight up (perpendicular to the floor) so it doesn't angle in under your foot.
4. Measure from the back of the heel to the tip of the longest toe.
5. Repeat for the other foot, and use the larger measurement.
6. Compare that length with the size chart for the specific brand you're buying.

Running Warehouse suggests measuring every year, because arches can change over time, sometimes lowering and lengthening the foot, sometimes rising and shortening it. If you last measured your feet years ago, don't assume the number still holds.

Should you size up for running shoes?

Usually, by about a half size. Running Warehouse says your standard running shoe size is typically a half size larger than your casual shoe, and Harvard Health says athletic shoes should be a half size larger than regular shoes. ASICS' own fit guide gives the same advice, around a half size larger than the size you usually get, and gives the reason: the further you run, the more your foot naturally expands.

"Half a size up" is a starting point, not a rule. The real test is the toe-room check below: if you have a thumb's width at your usual size in a particular model, you don't need to go up. And if you need more than a full size up to stop your toes touching, look at the width before the length. For a Couch to 5K beginner whose longest session is a 30-minute run, the goal is simply a shoe that doesn't pinch at the end of that run.

The thumb test, done properly

Cleveland Clinic's running-shoe guide says to keep a thumb's width between your longest toe and the front of the shoe. Running Warehouse is a little more flexible, allowing half to a full thumb's width, and the AAOS puts it at at least a half inch. How to check:

• Lace the shoe as you would for a run.
• Stand up with your weight on both feet, as Running Warehouse specifies.
• Press your thumb down next to the ball of your foot and around the toes, as Running Warehouse describes, to find where your longest toe ends.
• Check both shoes; your two feet may not match.

Width: the other half of size

ASICS says the width of your shoe is equally as important as the length. Width comes in letter codes, and the letters mean different things for men and women. Per Running Warehouse:

Some brands and reviewers use words (Regular, Wide, X-Wide) instead of letters, and Brooks writes the standard widths as 1D for men and 1B for women. Cleveland Clinic says you shouldn't feel pressure across the midfoot, and the AAOS says the toe box should leave room to wiggle your toes. If you fail either check at a length that's otherwise right, try the wide version. Our best running shoes for wide feet lists shoes that come in 2E and 4E.

Heel and midfoot

Length and width are only part of fit. Cleveland Clinic says your heel should feel snug without slipping. Running Warehouse's test: hold the back of the shoe and try to raise your heel; there should be little to no movement. The AAOS describes the same thing from the shoe's side: the heel counter, the back of the shoe that holds the heel in place, should grip your heel.

If the length is right but your heel lifts, Running Warehouse notes that different lacing techniques can help with heel slippage, as well as blisters, hot spots and bruised toes. Try that before changing size.

When to try on, and which socks

The AAOS says feet swell throughout the day, so try on shoes at the end of the day or after a workout. ASICS suggests the evening, when your foot is slightly bigger. Both say to wear the kind of socks you'll run in.

Socks are also a small fit adjustment. Running Warehouse notes that thinner socks increase the space inside a shoe, while thicker socks give a snugger fit. If a shoe is very slightly roomy, a thicker running sock may be enough; if it's slightly tight, a thinner one may help. It won't rescue a shoe that's the wrong size.

Men's vs women's sizing

Running Warehouse says there's approximately a 1.5 size difference between men's and women's shoes: a woman would go down 1.5 sizes in a men's shoe, and a man would go up 1.5 sizes in a women's shoe. Remember the width letters shift as well, since a D is a men's standard but a women's wide. Our beginner picks for women and beginner picks for men list every shoe's widths for that sizing.

Buying online: a sizing checklist

Most of the steps above can be done at home, which makes online buying workable if you're methodical about it:

1. Measure both feet using the tracing method, late in the day, and note the larger length.
2. Open the size chart for the brand you're buying, not a generic chart. We don't publish a cross-brand size converter, because we haven't found one from the makers that we can verify; the brand's own chart and your measured length are the reliable pair.
3. Pick the width code that matches your foot (see the table above), not just the length.
4. Check the seller's return policy before you order, so you can try the shoes properly.
5. When they arrive, try them indoors on a clean floor, in running socks, and run through the thumb test, heel test and midfoot check. Walk and jog on the spot for a few minutes. If they don't feel right straight away, send them back rather than hoping they'll break in.

As your runs get longer

ASICS' explanation for sizing up is that the further you run, the more your foot naturally expands. A Couch to 5K runner's longest session is a 30-minute run with a walk either side, per the NHS plan. If you move on to half or marathon training, where Hal Higdon's novice plans build the long run to 10 miles (Novice 1 Half) and 20 miles (Novice 1 Marathon), it's worth rechecking toe room with your current shoes at the end of your longest run, not only in the store. Toes that feel fine at mile 3 and cramped at mile 10 are a sign to revisit the size or width. When you get there, our first half marathon shoes page picks up the story.

Shoes with wide size ranges

If you're hard to fit, it helps to start with models that come in several widths, so you can change width without changing shoe. These three are badged for every level from Couch to 5K to the marathon, and each comes in at least three widths. The full ranked list for new runners is our best running shoes for beginners.

Signs you got the wrong size

• Too small: Running Warehouse's warning signs are toes that feel cramped or pinched.
• Too big: the heel slips, per Running Warehouse.
• Wrong width: pressure across the midfoot (Cleveland Clinic) or no room to wiggle your toes (AAOS) even though the length is right.
• Needs "breaking in": Harvard Health's advice is that shoes should feel right immediately, without a break-in period. If they don't, try another size, width or model.

If fit problems persist across several shoes, or you have foot pain, see a podiatrist or your doctor rather than cycling through sizes. For rubbing and blisters specifically, see how to prevent blisters when running.

Width is half of size, so if the letter rather than the number is your problem, go straight to best running shoes for narrow feet or best running shoes with a wide toe box.