15,700 Brits are expected to cheat at an office Christmas party this year

Methodology

How we worked it out

No survey measures how many people cheat at a work Christmas party in a given year. So the 15,700 figure is a modelled estimate, built three different ways from published data. Here is all of it.

What we counted

People in Great Britain who are in a relationship and have sex with someone other than their partner at a work Christmas party, in one year. Kissing is counted separately.

The three methods

Each method was run 200,000 times across the plausible range of its inputs. The central figure is the middle result. The low and high figures are the 10th and 90th percentiles.

Method	Low	Central	High
1. Last year's party	7,500	12,700	20,800
2. Lifetime poll	5,600	8,500	12,800
3. Yearly infidelity	23,300	36,400	55,400
Combined	11,800	15,700	20,700

Method 1: last year's party

• A 2019 study by Dectech found that 2% of people admitted, when asked anonymously, to kissing a colleague at the previous year's party. Asked directly, 7% said so. We used a range of 1% to 4%, centred on 2%.
• That is applied to the 21% to 24% of adults who go to a work party or meal (CGA by NIQ, 2025 and 2024) and to the 53,987,266 adults in Great Britain (ONS, mid-2025). This gives around 275,000 people kissing a colleague.
• The share who go on to have sex uses a YouGov poll of 1,162 adults (21 to 22 December 2010). In it, 2% said they had had sex at a work Christmas party and regretted it, and 9% said they had kissed someone and regretted it. That is a ratio of about one in five.
• About 21% of those people are assumed to be in a relationship (see below).

Method 2: lifetime poll

• In the same YouGov poll, 3% of 25 to 59 year olds said they had ever had sex at a work Christmas party and regretted it.
• If 3% of each year group ends up having done this, about 3% of one year group does it for the first time each year. One year group is about 867,000 people (ONS, mid-2025).
• We allowed for people who do it in more than one year (a multiple of 1 to 1.5), and applied the share in a relationship, raised slightly because regret is more likely when someone was cheating.
• The poll only counted people who regretted it, so this method is likely to undercount.

Method 3: yearly infidelity

• There are about 29.1 million employees in Great Britain (ONS, June to August 2026, adjusted from the UK figure).
• Between 62% and 71% are in a relationship. ONS reports that 62.1% of adults live in a couple, and around 9% more are in relationships but live apart.
• Published studies put the share of partnered people who have sex outside their relationship in a year at 2.3% to 5% (Whisman, Gordon and Chatav 2007; Richters and others 2014; Treas and Giesen 2000).
• Between 25% and 38.5% of that is with a colleague (YouGov 2015; Labrecque and Whisman 2017; Traeen and Thuen 2021).
• The share that happens at the Christmas party is assumed to be 8% to 30%, centred on 16%. This is based on workplace romance surveys by Vault (2019), which found 17% of office romances began at happy hours or holiday parties, and Reboot Digital (2017), which found 30% of first kisses between colleagues happen at the Christmas party.

Combining them

The three results are combined using a geometric average. That's the usual way to combine estimates that differ by multiples, and it stops the highest method dominating. It gives 15,700, with a range of 11,800 to 20,700. A simple average of the three would be 19,200.

The share in a relationship

In methods 1 and 2, about 21% of the people involved are assumed to be in a relationship (range 16% to 26%). This isn't polled anywhere, so we derived it. Around 65% of people at a work party are in a relationship, but single people are far more likely to start something new. We used the yearly infidelity rates above, the share of affairs that are with colleagues, the 17% of adults who have a new partner in a year (Natsal-3), and the 16% to 19% of couples who met through work (Natsal-3, YouGov 2026).

The kissing figures

The 275,000 is the Dectech 2% applied to work party attendance. The 57,000 is 21% of that.

How we picked Friday 11 December

This is a prediction, not a measurement.

• Dojo Bookings data shows the week starting 8 December 2025 took 34% of all festive bookings. The matching week this year starts on Monday 7 December.
• Fridays take between 33.0% and 43.8% of Christmas party enquiries (Tagvenue, 2025 and early 2026). VenueScanner's 2026 report puts it at 35.9%.
• Multiplying the two puts 11% to 15% of parties on the Friday of the peak week, with a central figure of 13%.
• CGA by NIQ reports that work celebrations peak on the last two Fridays before Christmas.
• 13% of 15,700 is about 2,000 people (range 1,500 to 2,700).

Erobella's platform data

• Figures are for Erobella's UK platform from September 2024 to October 2026. That covers two Christmases.
• "Demand" and "calls" mean taps on the call button on escort profiles. These are attempts to contact an escort, not confirmed bookings.
• Each day or night is compared with the same day of the week in ordinary weeks, after adjusting for the platform's growth. The chart shows the average of the two Christmases. Where a range is given, it shows the two years.
• The December Friday figure compares six pre-Christmas Fridays (10pm to 4am) with 101 other Fridays. The six were up 14%, 9%, 13%, 17%, down 2%, and up 9%.
• New Year's morning: calls between 6am and 9am ran at 3.2 times the normal level on our more cautious baseline, and at about four times on the hour-by-hour comparison used for the clock.
• Google search data is Google Trends for the term "escorts" in the UK, 2021 to 2025.

The polls

• YouGov, 1,552 GB adults, 18 to 19 November 2012. 17% have ever kissed a work colleague at a work Christmas party.
• YouGov for The Sun, 1,660 GB adults, 17 to 18 May 2015. 20% have had an affair, and 38% of those say it was with a work colleague.
• YouGov, 2,008 GB adults, 9 to 10 December 2018. 14% say passionately kissing someone other than their partner is not cheating. Under mistletoe at Christmas, 25% say so.
• YouGov, 2,199 GB adults, 8 to 9 December 2020. 58% of workers say they normally go to a work Christmas party in person.
• YouGov, 1,162 GB adults, 21 to 22 December 2010. Used in methods 1 and 2.

What to keep in mind

• The three methods disagree by a factor of four. The combined figure is our best estimate, not a count.
• The Dectech study does not publish a sample size.
• The yearly infidelity rates come from Australian and US studies, because no British figure exists yet.
• Two of the YouGov polls are more than ten years old.
• Demand for escorts is not a measure of cheating. Not everyone who contacts an escort is in a relationship.

Sources