Finding the right running shoe size involves more than just your usual street shoe measurement. Learning how to size running shoes correctly is the first step to preventing injury and ensuring comfort on every run.
A shoe that’s too small can cause blisters and black toenails. One that’s too big can lead to slippage and instability. The perfect fit supports your foot’s natural movement.
This guide will walk you through a detailed, step-by-step process. You will learn how to measure your feet, account for swelling, and choose the right fit for your running style.
How To Size Running Shoes
The process of sizing running shoes is methodical. It combines precise measurement with an understanding of your own physiology. You will need a few simple tools: a piece of paper, a pen, a ruler, and socks you typically run in.
Set aside at least 30 minutes to do this properly. Do not rush. Your feet are the foundation of your running, and their comfort is paramount.
Step 1: Measure Your Feet At The Right Time
Your feet swell throughout the day and during exercise. For the most accurate measurement, measure your feet in the late afternoon or evening. This is when they are at their largest.
If you run in the morning, this still gives you the necessary room for expansion. Always measure both feet, as one is often slightly larger than the other.
Why Foot Swelling Matters
During a run, blood flow increases and your feet can swell by half a size or more. A shoe that fits perfectly in the morning might feel tight after a few miles. Sizing with swelling in mind prevents this common issue.
Step 2: The Tracing And Measurement Method
This is the most reliable way to get your foot’s length and width. Stand on a blank piece of paper placed on a hard floor. Wear the socks you plan to run in.
- Have a friend trace the outline of each foot, holding the pen perpendicular to the paper.
- Step off and use a ruler to measure from the very back of the heel to the longest toe. This is your foot length.
- Measure the widest part of the forefoot (across the ball of the foot). This is your foot width.
- Record these measurements in both inches and centimeters for each foot.
Step 3: Determine Your True Size And Fit Needs
Use the measurement of your larger foot. Compare your foot length to a standard shoe size chart from a reputable brand. Note that sizing can vary between brands, so this is a starting point.
For running shoes, you typically need one-half to a full size larger than your measured street shoe size. This extra space is called “thumb’s width” and is crucial.
The Thumb’s Width Rule
When you try on a shoe, there should be about a thumb’s width of space (roughly 1/2 inch or 1.3 cm) between your longest toe and the end of the shoe. You should be able to wiggle your toes freely.
Check this by standing up with your weight evenly distributed. Your toes should not feel jammed or touch the end.
Step 4: Assess Width And Volume
Length is only one part of the fit. Width and volume (the height of the footbed) are equally important. A shoe that is too narrow can cause pain on the sides of your feet.
Signs of a good width fit include no pinching or bulging over the sides of the sole. The upper material should lay smoothly over your foot.
- Standard (D) Width: For men with average width feet.
- Wide (2E) or Extra Wide (4E): For men with wider feet.
- Standard (B) Width: For women with average width feet.
- Wide (D) Width: For women with wider feet.
Step 5: The Final Fit Test
Never buy running shoes without a thorough fit test. If shopping online, ensure the retailer has a good return policy for unworn shoes.
- Put on both shoes with your running socks and lace them up snugly, but not tight.
- Stand up and walk around the store. Jog if possible on a treadmill or clear area.
- Check for heel slippage. Your heel should be held firmly with minimal lift.
- Feel for hot spots or pressure points. These will only get worse on a run.
- Ensure the shoe bends at the same point your foot flexes.
Common Sizing Mistakes To Avoid
Many runners make simple errors that lead to discomfort. Being aware of these can save you from pain and wasted money.
Assuming Your Size Is Consistent
Your shoe size can change over time due to age, weight fluctuations, and pregnancy. Relying on the size you’ve always worn is a mistake. Always measure and try on shoes before purchasing, even from a brand you know.
Ignoring Sock Thickness
The socks you wear during your fit test must be the socks you run in. A thin liner sock versus a cushioned athletic sock can change the fit significantly. Bring your own socks to the store for the most accurate test.
Fitting To A Snug Feel
Running shoes should not fit snug like dress shoes. They need room for expansion. A common error is choosing a shoe that feels “just right” when sitting down, but becomes painfully tight when standing and running. Always judge the fit while standing with full body weight.
Special Considerations For Different Runners
Not all feet and running styles are the same. Your individual needs play a big role in finding the perfect size.
Sizing For Trail Running Shoes
Trail shoes often have a more protective toe cap. You still need the thumb’s width of space, but you might prefer a slightly more secure fit in the heel to prevent movement on uneven terrain. Some trail runners go up a half size to accomodate thicker socks or orthotics.
Sizing With Orthotics Or Custom Insoles
If you use orthotics or aftermarket insoles, you must try on shoes with them inserted. These devices take up volume inside the shoe. You may need to go up a half size or select a model with a higher volume to prevent the top of your foot from feeling compressed.
Sizing For Wide Feet And Bunions
For wide feet or conditions like bunions, length is not the only concern. Look for shoes available in wide widths. Models with a spacious toe box and flexible, forgiving uppers are ideal. Do not try to size up in length to compensate for width, as this can cause heel slippage.
Sizing For Racing Shoes
Racing flats and super shoes often have a more aggressive, performance fit. They may fit more snugly than your daily trainers. The general rule of thumb’s width still applies, but the overall feel will be more locked-down. Always test race shoes before race day.
When And How To Replace Your Running Shoes
Even perfectly sized shoes wear out. The cushioning and support degrade over time, which can change the feel and lead to injury.
Most running shoes last between 300 to 500 miles. Track your mileage in a log or app. Signs you need new shoes include noticeable wear on the outsole, a feeling of reduced cushioning, or new aches and pains that weren’t there before.
When you buy a new pair, do not assume you will take the same size. Re-measure your feet and try on the new model, even if it’s the same as your old one. Brands update their lasts and designs frequently.
FAQ: How To Size Running Shoes
How Much Bigger Should Running Shoes Be?
Running shoes should typically be one-half to a full size larger than your standard street shoe. The key indicator is a thumb’s width of space between your longest toe and the shoe’s end when standing.
Should You Size Up For Running Socks?
You should always try on running shoes with the socks you intend to wear. If your running socks are significantly thicker than everyday socks, you may need to account for that extra volume, potentially by sizing up slightly or choosing a wider model.
How Should Running Shoes Fit In The Heel?
The heel should fit snugly with minimal lift or slippage when you walk or run. Your foot should not slide up and down. A secure heel counter is essential for stability and preventing blisters.
What If One Foot Is Bigger Than The Other?
This is very common. Always size your running shoes to fit your larger foot. You can use an insole or a heel pad in the shoe for the smaller foot to fine-tune the fit and prevent it from sliding.
Can You Stretch Running Shoes That Are Too Small?
It is not recommended to buy running shoes with the intent to stretch them. Materials may give slightly over time, but a shoe that is too short or narrow from the start will likely cause problems. It is better to find the correct size from the beginning.
Finding the perfect running shoe size requires a little time and attention, but the payoff is immense. Properly fitted shoes help you run longer, more comfortably, and with less risk of injury. Remember to measure both feet in the evening, use the thumb’s width rule, and always do a thorough fit test. Your feet will thank you for it mile after mile.