What’s the Carbon Footprint of Walking Vs Biking? Carbon Emissions by Transport Type

There are many available means of transportation in modern life that can save time and energy, but when you consider the carbon footprint of walking versus other forms of travel, you might be surprised by the impact you can make.

Does walking have a carbon footprint, and if so, how can it be measured?

This guide examines the carbon emissions of various transport types, providing the information necessary for travelers to make smart, eco-conscious decisions about their means of travel.

It also explains the real carbon footprint of walking versus biking and other vehicles by examining the carbon footprint of a person and the energy we use.

What Is a Carbon Footprint?

The topic of carbon footprints and how to reduce them is the crux of many environmental conversations and arguments. Before looking to analyze the carbon footprint of walking, this article first considers the question “What is a carbon footprint?”

Most of anything a person can fathom has a carbon footprint, from a single individual to a corporation or an isolated item to a merchandise franchise.

The carbon footprint of an activity, such as walking, can also be measured.

Anything — be it a living creature, a manufactured product, or a single choice — which emits greenhouse gasses (GHG) has a carbon footprint. Greenhouse gases are those that capture and retain atmospheric heat, essentially blanketing and insulating the earth.

Thus, the more GHGs released into the air, the thicker and warmer the atmosphere becomes.

The most well-known and abundant GHG is carbon dioxide (​​CO₂), which accounts for nearly 80% of GHG emissions, according to the Environmental Protection Agency (EPA).¹⁸ Other recognized GHGs include methane (CH₄) at 11.5%, nitrous oxide (N₂O) at 6.2%, and fluorinated gasses at 3%, including hydrofluorocarbons (HFC), nitrogen trifluoride (NF₃), perfluorocarbons (PFC), and sulfur hexafluoride (SF₆).

Combined greenhouse gas emissions are often referred to as carbon dioxide equivalent, or CO₂e in scientific literature.

Understanding the Carbon Footprint of Walking

At first glance, it may seem that the act of walking from one place to another would not have a carbon footprint at all, but this is not actually the case. There is more to the carbon footprint of walking than most people would realize, and every aspect must be taken into account to fully understand the extent to which walking improves upon other modes of transportation.

To estimate the carbon footprint of walking, an individual must consider:

The Amount of CO2 Exhaled During Respiration

An individual emits more carbon dioxide when exercising than when resting, resulting in increased CO₂ through respiration with walking than in non-active modes of transportation.

The Carbon Footprint of the Food Required To Refuel After Exercise

An individual burns more calories exercising than resting and requires more food to refuel, equivalent to the vigor of the exercise and calories burned. Thus the additional amount of food required and the carbon footprint of that food also goes into the calculations for walking emissions.

To put this in perspective, a person who refuels with a salad and vegetables gathered from their backyard garden is creating a much smaller footprint than a person who refuels on a meal from a fast food restaurant.

The Carbon Footprint of Footwear

Though it is not an absolute necessity for individuals to wear shoes when walking, it is certainly the norm. Each pair of shoes has an associated carbon footprint which is the combination of emissions from material sourcing, product manufacturing, product transportation, and end-of-life management.

Increased walking results in increased wear on shoes which would reasonably lead to more frequent shoe replacements. The carbon footprint of shoes does depend upon the type of shoes purchased.

Locally manufactured shoes and shoes manufactured from recycled materials will have a lower carbon footprint.

The Carbon Footprint of Road and Sidewalk Infrastructure

The act of walking is dependent upon certain infrastructure, particularly in urban areas where walking is a more prevalent means of travel.

Thus, the carbon footprint associated with the maintenance and upkeep of sidewalks and roadways used for foot travel must also be a factored coefficient.¹⁴

Estimating the Carbon Footprint of Walking

An earlier section of this article outlined the elements that make up the carbon footprint of walking, and this section sets about the task of actually calculating the carbon footprint of these elements one by one.

CO2 Respiration During Walking

The amount of CO₂ exhaled during walking is dependent upon the pace of the walk, and carbon footprint calculations rely on an average pace.

Adults in good health are thought to walk approximately 3 mph on average, a number which decreases gradually with age.³⁰ According to the GLOBE Program Scientists’ Blog, an average adult exhales roughly 0.7 to 0.9 kg (1.5 to 2 lbs.) of CO₂ every day, though some estimates suggest the actual number is closer to 2.3 lbs.^19,21

Walking at a 20-minute pace, or 3 mph, the average person burns approximately 83 kilo-calories per mile, compared to 28 kilo-calories (kCal) burned in a resting state for the same time frame, an incremental increase of 55 kCal per mile for walking over resting.²¹

Using the lower estimate of 0.7 kg of CO₂ per 2,000 kCal per day, calculations show 0.019 kg of additional CO₂ expired for each mile or 20 minutes walked, or 0.057 kg per hour spent walking.²¹

Carbon Footprint of Food Refueling After Walking

There is so much individual variation in what an individual chooses to eat to replenish their calories, making it extremely difficult to measure. Yet, many sources indicate that food refueling is a large contributor to the carbon footprint of walking.¹⁴

The way the food is produced, transported, and packaged all contributes to the overall carbon footprint. An article published in the National Institute of Health explores the carbon footprint of cooking at home versus fast food, finding that the consumption of meat had the highest overall impact on the CO₂e associated with diet.³²

The University of Michigan Carbon Footprint Factsheet explains that a single serving of beef contributes 6.61 pounds of CO₂e to the atmosphere.⁵

Another NIH study from 2019 found that the average U.S. diet produces 2.21 kg of CO₂e per 1000 kcals but other sources indicate a higher number at 3.17 kg.^25,33 Meanwhile, a 2020 study of global diets and energy compensation through food intake after walking or cycling found that emissions of food refueling after walking approximated 0.15 kg of CO₂e per km or 0.24 kg CO₂e per mile.^15,24

Carbon Footprint of Shoes

The majority of footwear is not manufactured using green technologies, and shoes can have a big impact on carbon footprint. According to MIT News, two-thirds of the carbon footprint of footwear (specifically running shoes) comes from the manufacturing process, and the carbon footprint of footwear can reach 30 pounds per pair.⁶

Experts recommend replacing walking shoes at least every 500 miles. Thus, a walker averaging the suggested 10,000 steps per day could need new shoes up to 3 times per year, compared to a non-walker requiring between 1 and 2 pairs per year.

This means that a regular walker may contribute around 90 pounds of CO₂ to the atmosphere each year just by replacing their shoes.⁷

Carbon Footprint of Road/Sidewalk Infrastructure

As roadways and sidewalks are used for many purposes aside from walking, the carbon footprint of the infrastructure should be spread out to its many uses. Some estimates suggest that the carbon footprint approximates 2 grams of CO₂e per km (3.22 g per mile).¹⁴

The Carbon Footprint of Walking vs Biking

Walking and biking are two forms of transportation or travel that are often recommended as alternatives to driving and even public transportation. But how do these two activities measure up against each other in terms of carbon footprints?

This section breaks down the relevant elements to contrast walking vs biking from an environmental viewpoint.

In the previous section, a carbon footprint estimate for walking was derived. When examining the carbon footprint of cycling, several of the same components relevant to walking must be factored in.

The carbon footprint of road infrastructure and maintenance is the same coefficient that is used when conducting calculations for walking emissions; approximately 3.22 g/mile. The amount of CO₂ released during respiration and the food required for refueling are also important factors in cycling, but the numbers look a bit different than they do for walking.

CO2 Respiration During Cycling

Traveling at an average cycling speed of 14 mph, a person in average health and of average size will burn around 30 calories (kcal) per km or 48 kcals per mile.²⁵ Subtract from this number the approximate 20 kcals burned in a resting state for an equivalent timeframe, and the resulting incremental value is 28 kcals/mile cycling.

Note that cycling at a moderate pace appears to be less energy-intensive than walking at a moderate pace.^12,13

Carbon Footprint of Food Refueling After Cycling

Somewhat surprisingly, individuals appear to emit less CO₂e through food intake after cycling than after walking, though considering the lesser energy expenditure, it makes sense. Food refueling after cycling is estimated to produce approximately 0.08 kg of CO₂e per km or 0.13 kg/mile.¹⁵

Carbon Footprint of Equipment

Finally, instead of looking at the emissions associated with the manufacture, transport, and disposal of shoes, this analysis must consider the GHGs associated with the manufacture, transport, maintenance, and end-of-life treatment of the bicycle. The following section explores this in more detail.

What Is the Carbon Footprint of a Bicycle Versus an Electric Bicycle?

The carbon footprint of a bicycle is an aggregate of many factors, such as manufacturing, lifetime maintenance, and end-of-life management. A traditional bicycle has a carbon footprint that looks very different from that of an electric bicycle or E-bike as a traditional bicycle is powered entirely by physical force while an E-bike is partially motorized and may be digitized as well.²⁸

This section compares and contrasts the different domains that contribute to the carbon footprint of traditional bicycles versus electric bicycles.

According to leading bicycle producer Trek’s 2021 sustainability report, the carbon footprint of manufacturing a traditional bicycle ranges from 116 to 197 kg of CO₂e depending on the model components and dimensions. The company’s E-bikes have a somewhat heftier carbon footprint of 229 kg CO₂e due to their batteries, motors, and chargers.²⁶

The European Cycling Federation reports that the carbon footprint of the production and maintenance phases of a traditional bicycle generates approximately 5 grams of CO₂e per km, assuming a lifespan of 8 years and an annual distance of 2,400 km. An electric pedal bike was estimated at 6 grams per km.³¹

The Carbon Footprint of Walking vs Driving (Motorized Travel and Electric Travel)

There is little doubt in anyone’s mind about the improved carbon footprint of walking vs driving, but a look at the numbers sends the message even more clearly.

While an individual is thought to expire around 0.019 kg of incremental CO₂e with each mile walked, the average passenger vehicle generates 400 grams of CO₂ per mile just in tailpipe emissions.

This equates to .4 kg per mile without factoring in production, maintenance, or disposal, amounting to a whopping 4.6 metric tons of CO₂e annually, per the EPA.¹¹

What Is the Carbon Footprint of a Motorized Car vs an Electric Car?

Gas-powered passenger vehicles, such as sedans, SUVs, and minivans create a smaller footprint than larger vehicles such as pick-up trucks, semis, and heavy machinery (See Truck CO₂ Emissions Per Km Calculator). Conversely, gasoline-powered passenger vehicles create a much larger carbon footprint than electric vehicles.

The carbon footprint of lithium-ion battery production is the biggest contributor to the overall carbon footprint of electric vehicles with some battery production generating up to 16 metric tons of CO₂e when fossil fuels are used to power production plants. However, according to the MIT Climate Portal, the largest source of electric vehicle emissions usually comes from the electric power required to charge the vehicle, particularly in more carbon-intensive electric grids.¹⁶

However, the U.S. Department of Energy (DOE) reports the national averages showing that electric vehicles generate approximately 2,800 pounds of CO₂e per year over their lifetimes, compared to 12,500 pounds annually from their gasoline counterparts.¹ Use the DOE’s tool to see the averages for different states, factoring in the carbon intensity of the electric grid.

What Are the Benefits of Walking?

There are many benefits of walking that have been explored extensively through years of study.

According to Harvard Health, walking has benefits beyond the obvious and most well-known perks of increased energy and heart health.¹⁰

The following is a short list of some of the most researched and validated walking benefits.^3,27

• Improves heart health
• Reduces risk of stroke
• Extends longevity
• Enhances weight loss
• Reduces cravings for sweets and reduces stress eating
• Reduces risk of breast cancer
• Reduces arthritis and arthritis-related joint pain
• Boosts immunity
• Improves bone density and muscle tone
• Improves mood and sleep

Carbon Footprint of Walking: Lesser Known Walking Facts

Here are a few informative walking facts.

• Walking, regardless of intensity or pace, has been shown to increase longevity and reduce the risk of premature mortality²³
• The average person walks the equivalent of three laps around the earth in their lifetime
• Regular, brisk walks can be as effective as medication in combating depression
• Walking can help counteract the effects of aging in the brain²⁹
• Americans take fewer steps daily than people in other countries²⁰

Aside from health benefits, walking has environmental benefits, too. It is one of the modes of transportation that emits the lowest carbon footprint.

How Far Does the Average Person Walk in a Lifetime?

Have you ever wondered “How far does the average person walk in a lifetime?” There are many approaches to answering this question, and one study estimated that the average person would walk nearly 75,000 miles over the average lifetime (80 years).⁸

Other estimates are much larger while still others are much more conservative.

Carbon Footprint Calculation

Carbon footprint calculation is a process of using all available information relevant to the domain being measured to generate an accurate estimate or calculation of the greenhouse gasses emitted. For example, in estimating the carbon footprint of a single household, an individual must consider:

• The carbon footprint of the home itself: Emissions related to construction + emissions related to maintenance and lawn care + emissions related to home energy – CO₂e sequestered by trees and plants on the property
• The carbon footprint of vehicles owned by household members: Emissions related to vehicle production + emissions related to vehicle maintenance + emissions related to vehicle operation
• The carbon footprint associated with each household member including pets: Emissions related to individual waste + emissions from individual energy usage + emissions from individual travel + emissions from individual activities (medical care, travel, food and goods consumption, etc.)

Understandably, it can be quite difficult to accurately calculate the carbon footprint of any given thing, and most calculations are likely to underestimate carbon footprints due to the limits of available information and the complexity of factoring in each variable.

The EPA’s Carbon Footprint Calculator estimates household carbon footprints by looking specifically at home energy usage, transportation, and household waste.⁴

Carbon Emissions by Transport Type

The transportation sector is the largest producer of greenhouse gas emissions in the United States. As much as 83% of the carbon emissions from this sector are generated by motor vehicles, led by personal vehicles like cars and trucks.

This final section of the article examines carbon emissions by transport type with particular emphasis on modes of transportation that have not been previously touched upon.⁹

Carbon Footprint of Airplanes

Many people must rely upon air transport for international travel, and the carbon footprint of these trips can stack up quickly. For individuals who travel regularly for work, the travel carbon footprint calculator may be the trick to understanding and reducing that unsavory impact.

The International Energy Agency reports that air travel accounted for 2% of global GHG emissions and around 10% of transportation emissions in the year 2022 with nearly 800 metric tons of CO₂e and a growth rate that is outstripping other forms of travel.²

A single airplane flight from New York to California can generate more than 65 tons of CO₂e, with air travel estimated at 53.3 pounds of CO₂e per mile.¹⁷

Carbon Footprint of Public Transportation

According to an article in UCLA Transportation, using public transportation can cut CO₂e emissions by nearly half.²² In fact, it is estimated that public transportation already saves the United States from 37 million metric tons of CO₂ emissions each year.

In 2019, according to the Congressional Budget Office, personal vehicles generated 0.47 pounds of CO₂ per passenger mile compared to 0.39 for buses, 0.30 for passenger railroads, and 0.17 for rail transit.⁹

There are a number of factors that increase the carbon footprint of walking. Making smart choices when it comes to your food consumption and the brands of shoes you purchase will help you minimize your footprint.

Additionally, trees have been proven capable of capturing carbon in the environment which makes them an effective form of lowering your carbon emissions. With the help of tree-planting initiatives, such as a one-month carbon offset, you can further lower your emissions.

Although walking is not a viable form of travel in many rural areas, urban dwellers may find it a feasible, health-promoting, and environment-supporting alternative to driving and even public modes of transportation. Review this article to learn many interesting and informative statistics to better understand the true carbon footprint of walking.

Frequently Asked Questions About the Carbon Footprint of Walking