How long to walk if you sit all day

About an hour a day. In over 1 million people, those who sat more than 8 hours a day but did about 60 to 75 minutes of moderate activity, like brisk walking, had no clear extra risk of dying compared with equally active people who sat under 4 hours a day (Ekelund, 2016). The details, what cut sitting time at work, and a new study of 8,556 US adults are below. Every number links to its source.

Where the hour comes from

A 2016 analysis followed 1,005,791 people. It split them into four equal groups by how active they were, from least to most active, and also by hours sitting a day. Every group was compared with the most active people who sat under 4 hours a day (Ekelund, 2016).

The most active group, about 60 to 75 minutes a day of moderate activity like brisk walking by the authors' estimate: sitting more than 8 hours a day came with no clear rise in risk of dying (4% higher, which could be chance) (Ekelund, 2016).
The least active group: sitting more than 8 hours a day came with a 59% higher risk of dying, and sitting under 4 hours with a 27% higher risk (Ekelund, 2016).
The second least active group: sitting under 4 hours a day came with a 12% higher risk of dying (Ekelund, 2016).

The paper's summary doesn't give the results for the other groups. These numbers come from following people over years. The study didn't test what happens when someone adds exercise.

The short version

In over 1 million people, about 60 to 75 minutes a day of moderate activity, like brisk walking, went with no clear extra risk of dying from sitting more than 8 hours a day (Ekelund, 2016).
Watching 3 or more hours of TV a day came with higher risk at every activity level except the most active quarter, where a clear rise showed only from 5 hours a day (Ekelund, 2016).
In trials, sit-stand desks cut sitting at work by about 100 minutes a workday compared with ordinary desks over the first few months. The evidence was low quality (Shrestha, 2018).
In a new US study, sitting 8 or more hours a day came with a 51% higher risk of dying than sitting under 6 hours (Xu, 2026).

The pooled study in more detail

A 2016 analysis pooled 13 studies of 1,005,791 people followed for 2 to 18 years, during which 84,609 died. The researchers put everyone into groups by hours sitting a day and by how active they were, then compared each group with people who sat under 4 hours a day and were in the most active quarter (Ekelund, 2016).

People in the most active quarter who sat more than 8 hours a day had no clear rise in risk of dying (4% higher, which could be chance) (Ekelund, 2016).
People in the least active quarter who sat more than 8 hours a day had a 59% higher risk of dying (Ekelund, 2016).
People in the least active quarter who sat under 4 hours a day still had a 27% higher risk of dying (Ekelund, 2016).

The most active quarter did more than 35.5 MET-hours of activity a week (Ekelund, 2016). The authors put that at about 60 to 75 minutes a day of moderate activity, and say this level of activity "seems to" remove the extra risk of long sitting. A MET-hour is an hour of activity weighted by how hard it is.

TV time was different. In 6 studies of 465,450 people, watching 3 or more hours a day came with a higher risk of dying at every activity level except the most active quarter, where a clear rise showed only at 5 or more hours a day (Ekelund, 2016).

What cut sitting time at work

A 2018 Cochrane review gathered 34 studies of 3,397 people trying to sit less at work (Shrestha, 2018).

Compared with ordinary desks, sit-stand desks, sometimes with advice, cut sitting at work by about 100 minutes a workday over the first 3 months, in 10 studies, and by about 57 minutes a day over 3 to 12 months, in 2 studies. The reviewers rated the evidence low quality, and no study followed people for longer (Shrestha, 2018).
Short breaks of one to two minutes every half hour cut sitting at work by about 40 minutes a day compared with two 15-minute breaks, in one study with low-quality evidence (Shrestha, 2018).
Walking plans, information and counselling had small or inconsistent effects.

The new study

Xu and colleagues followed 8,556 US adults with no known heart disease or stroke for about 7 years, and 670 died. Each person said once how many hours they usually sat a day, not counting sleep, and how much exercise they did in their free time, counted in minutes a week with minutes of hard exercise counted twice (Xu, 2026).

8,556 US adults, 7 years. Sitting 6 to under 8 h a day showed no clear rise in risk.

Compared with sitting under 6 hours a day, sitting 6 to under 8 hours showed no clear rise in risk of dying, and sitting 8 or more hours came with a 51% higher risk (Xu, 2026).
People who sat 8 or more hours and exercised less than 150 minutes a week had a 97% higher risk of dying than people who sat under 6 hours and exercised 150 minutes or more (Xu, 2026).
People who sat 8 or more hours but exercised 150 minutes or more had a 44% higher risk, which could be chance (Xu, 2026). The authors say their results don't show that exercise cancels out long sitting.

The two studies grouped people differently. In Xu's study, the more active group started at 150 minutes a week, about 21 minutes a day, with no upper limit. The 2016 analysis described its most active quarter as about 60 to 75 minutes a day. So the two results don't directly test one amount of exercise against another.

Where to start

If you sit more than 8 hours a day, the most active people in the pooled study did about an hour a day of moderate activity like brisk walking.
If you work at a desk, sit-stand desks cut sitting time in trials, at least for the first months.
Long evenings of TV count too. In the pooled study, they came with higher risk even for fairly active people.

How far to trust these numbers

Both mortality studies here watched what people already did. They can't show that sitting less or exercising more would change anyone's risk by these amounts.
In both, people reported their own sitting and exercise, and people who are already unwell may sit more and exercise less, so illness may explain some of the link between sitting and dying.
A 2019 analysis that measured activity with devices instead of questions pointed the same way. The most sedentary quarter had more than twice the risk of dying of the least sedentary quarter (Ekelund, 2019).
The sit-stand desk trials were small and short. They show that desks cut sitting time, and don't show any effect on health.