Why Everyone on Earth Commutes for 78 Minutes a

Picture two people waking up on the same Tuesday morning. One is in Lagos, navigating a packed danfo bus through traffic that defies both physics and patience. The other is in rural Denmark, cycling unhurried down a bike lane that cost more per meter than most people's cars. Their incomes differ by an order of magnitude. Their infrastructure differs by a generation. Their language, diet, and relationship to the state differ completely.

And yet, statistically, they will spend almost exactly the same amount of time traveling today.

That's the finding at the center of a 2025 research paper—covered recently by SciShow—that dug into what a 2023 study called "the global human day." When researchers pulled together time-use data from 145 countries spanning 2000 to 2019, they found that across staggering differences in wealth and lifestyle, the global average for daily personal travel time converges at 78 minutes, with a margin of error of only 12 minutes. Not just commuting to work—all personal travel: errands, social visits, the school run, everything.

The number is strange enough that it warrants sitting with for a moment before reaching for an explanation.

The Measurement Problem This Solved

Cross-country time-use research has a long history of frustration. Economists, anthropologists, sociologists, and historians have all taken runs at the question of how humans spend their 24 hours, and they've mostly talked past each other. As SciShow host Madelyn Leembruggen explains: different disciplines "tend to focus on just a slice of the pie using methods that make it really difficult to combine results across studies." National surveys use different categories, different age brackets, different definitions of what counts as "work" or "leisure." Reconciling them is less like assembling a puzzle and more like assembling a puzzle where half the pieces came from a different box.

The 2023 global human day project tried to cut through this by harmonizing data across 145 countries and applying consistent methodology—a substantial methodological lift that took years and considerable statistical creativity to account for missing data and demographic variation.

What emerged was a picture of which human activities vary enormously across development levels and which ones don't. Growing and collecting food, for instance, "takes up more than an hour a day in some low-income countries and less than 5 minutes a day in many high-income countries"—a reflection of mechanized agriculture, global supply chains, and the time cost of poverty. Travel time showed no such gradient. It just... didn't move.

What 78 Minutes Actually Means

The researchers propose a dual-constraint explanation: travel has both an upper limit and a lower limit, and humans collectively bump against both.

The upper limit is intuitive. Travel is tiring, expensive, and time-consuming. At some point, more of it crowds out everything else—sleep, food, work, relationships. So there's a ceiling beyond which populations don't go, at least not on average.

The lower limit is more interesting, and the researchers tie it to something deeper than logistics. They suggest it reflects "a psychological need for people to go out and explore, to stretch their legs and be exposed to a complex environment." Leembruggen frames it in evolutionary terms: "if you think about our hunter-gatherer days, we probably wouldn't have been able to hunt or gather all that much if we stayed at home all day." Whether that's the precise mechanism or a useful metaphor is an open question—evolutionary psychology explanations for modern behavior deserve some scrutiny—but the underlying observation holds: people don't minimize travel when given the option. They seem to seek a certain amount of it.

What's genuinely puzzling is that the distance traveled shows no correlation with the time. Populations averaging fewer than 10 kilometers of daily travel and those averaging more than 150 kilometers both arrive at roughly the same 78 minutes. The mode of transport doesn't break the pattern either—walking, driving, and buses all produce the same result. People in richer countries go farther in the same time; people in poorer countries go shorter distances but take equally long. The clock, not the kilometer, appears to be the governing variable.

This has a name in urban planning circles: Marchetti's constant, or the travel time budget. The Italian physicist Cesare Marchetti proposed in the 1990s that humans have historically allocated about an hour of daily travel time across civilizations—ancient Rome to modern Tokyo. The 78-minute figure from this newer, more rigorous research updates and complicates Marchetti's claim, but the core intuition appears to survive contact with the data.

Where This Gets Useful—and Where It Gets Complicated

The climate implications are where this finding earns its keep, and also where it requires the most careful handling.

The researchers point to a cautionary historical example: between 1975 and 2002, European cars became dramatically more fuel-efficient. Efficiency gains were large enough that, if driving habits had stayed constant, total energy consumption from personal transport would have dropped significantly. Instead, it increased. In Germany alone, daily distance traveled per person climbed from 25 to 38 kilometers over that period. People didn't pocket the efficiency gains as saved energy; they spent them as additional distance.

This is the rebound effect—a phenomenon well-documented in energy economics and consistently underweighted in policy projections. More efficient cars didn't reduce energy consumption; they enabled more travel within the same time budget.

The implication the researchers draw is that we need to rethink the unit of measurement for transportation efficiency. As Leembruggen puts it: "we need to consider how much energy is consumed per hour, not per kilometer, which is how we've traditionally thought about it."

Reframing from kilometers to hours produces different policy conclusions. An electric car and an electric bus, she notes, may use similar energy per kilometer per passenger—but "cars use almost twice as much energy per hour, meaning that buses are actually the more energy-efficient place for transit infrastructure investment." If travel time stays constant regardless of mode or speed, then the energy question is not how far we go per liter (or kilowatt-hour), but how much energy we burn per hour of the travel we will, apparently, always take.

This is a genuinely useful reframe. It also has limits worth acknowledging. The 78-minute figure is a population average across countries—within any given country, and certainly within cities, the variance is enormous. The commuter in a car-dependent American suburb spending three hours a day on the road is very much a real person, not a statistical outlier to be waved away. Averages can be tools for good policy or cover for bad policy, depending on how they're wielded. And the rebound effect argument, while real, can cut in multiple directions: it's been used both to advocate for public transit investment and to argue, less convincingly, that efficiency improvements are pointless.

There's also something worth noting about what the data doesn't capture. The 2000–2019 window predates the remote work experiment forced by COVID-19, which genuinely disrupted commuting patterns for large segments of the global workforce. Whether the 78-minute figure is reasserting itself post-pandemic—whether the psychological pull toward exploration and movement is drawing people back toward their travel time budget—is a question the researchers are presumably watching.

The Clock We All Share

Collective global human time runs to roughly 190 billion hours per day. That's the actual resource at stake when we talk about addressing climate change, biodiversity loss, or any other challenge that requires coordinated behavior at scale. Understanding how that time is spent—and what's fixed versus what's malleable—matters for anyone trying to design interventions that work with human behavior rather than against it.

The 78-minute finding suggests that trying to reduce how long people travel may be harder than trying to reduce how much energy they burn while doing it. That's not a counsel of despair. It's a design constraint. And design constraints, honestly understood, tend to produce better solutions than optimistic assumptions about how people will change their habits when given the right incentives.

The commute isn't going away. The question is what it costs the planet while you're on it.

By Olivia Meng, Climate & Environment Correspondent