The High Pay Centre said some of the country's lowest paid jobs have been the most important during the Covid-19 pandemic, and that income inequality may now be harder to justify.
The think tank estimates the median annual pay of FTSE 100 CEOs was £2.7 million (around £827.69 per hour of their 12.5-hour days) in 2020 – the latest data available.
Assuming they start work at 8.30am, they had already earned a Doncaster full-time worker's median salary (£28,761 in 2021) by around 6.30pm on Thursday, January 6 – just the third working day of the year.
This means it would take an average Doncaster employee 94 years to earn the annual salary of a top CEO.
The median is used to stop figures being skewed by particularly small or large wages, and it is assumed that CEOs work 62.5 hours a week.
High Pay Centre director Luke Hildyard said: "Covid-19 has shown how much we all depend on each other. Some of the lowest-paying jobs have played the most important role to keep society functioning through the pandemic.
"With the value of the UK economy reduced, there’s also greater pressure to share what we do have more evenly.
"In this context, vast CEO to worker pay differences may be harder to justify."
The average Doncaster salary was down from £29,008 in 2020.
Meanwhile, the High Pay Centre said CEO pay had also fallen from £3.3m in 2019, making it the first time since 2011 that CEOs have needed to work into a fourth day to earn the same annual pay as a full-time worker.
Danny Magill of the Equality Trust, said: "In a year where this country has faced unprecedented economic challenges, most CEOs pay packages barely changed, showing how detached high earning CEOs’ have become from the realities of ordinary working people.
"While the taxpayer supported large companies, it was essential workers that kept the economy afloat throughout the pandemic, often for low wages, with no sick pay and at great personal risk."
With women in Doncaster earning less on average for working full-time than men (£23,583 compared to £30,871), FTSE 100 bosses will surpass their annual wage in just 28 hours.