A study of 2,000 adults found toiletries, phone chargers and travel adapters topped the list of the most commonly forgotten items.
While many have forgotten things where alternative replacements could usually be bought at their destination, such as sun cream (23 per cent) and swimwear (19 per cent), nearly one in five have travelled without their prescription medicine.
The research, commissioned by M&S Bank, also found 17 per cent have left their prescription glasses at home, while one in five have forgotten their shoes.
The top reason for forgetting an essential holiday item was having too much to remember (40 per cent), while a third put it down to leaving the house in a rush.
Oversleeping (18 per cent), not planning ahead (25 per cent) and leaving someone else to pack for them (20 per cent) were also among the reasons for going away without essentials.
Paul Stokes, from currency and insurance provider, M&S Bank, said: “Whether you’re planning a staycation or a trip abroad, holidays are an exciting time.
“But understandably, this year more than ever, holidays will be extremely important to many of us.
“And even though many of us will have been thinking about our next holiday for quite some time, it’s still easy to forget certain things.
“It sounds simple but make a list of everything you intend to take or sort pre-trip – paying particular attention to your passport if traveling abroad, along with tickets, currency and insurance.”
The research also found that 43 per cent of adults want their holidays in 2021 to be perfect, but 55 per cent admitted that forgetting something is one of the biggest worries prior to taking a trip.
More than half have even taken measures, such as setting reminders, writing lists and packing in advance, to help remember everything they need.
Despite this, 44 per cent of travellers have had to buy replacement items while they were away after leaving something at home.
And 16 per cent have had to pay for extra nights’ accommodation when their travel plans have been disrupted after forgetting to purchase travel insurance.
Nearly half (46 per cent) have had to pay out after forgetting something for their holiday, with the cost of leaving things behind amounting to an average of £641 each.
Research also found that despite ongoing disruption to travel over the last 16 months, 48 per cent of adults plan to take a holiday this year, with 32 per cent intending to staycation in the UK.
However, two thirds (68 per cent) of those planning a staycation are opting not to insure their trip, despite 18 per cent spending more than expected on purchasing their holiday this year.
Paul Stokes added: “Our research shows that many holidaymakers are actually planning to spend more on their holiday this year, and with the average staycation costing in the region of £1000 per person, they could be leaving themselves exposed to significant unexpected costs.
“Ensuring you have adequate insurance cover in place can help alleviate any worries, so more time can be spent enjoying that well-earned break.”
Top 20 things Brits forget to take on holiday:
1. Toiletries (33 per cent)
2. Phone charger (30 per cent)
3. Travel adaptor (30 per cent)
4. Sunglasses (26 per cent)
5. Suncream (23 per cent )
6. General clothing (21 per cent )
7. Headphones (21 per cent)
8. Swimwear (19 per cent)
9. Shoes (18 per cent )
10. Underwear (17 per cent )
11. Prescription medicine (17 per cent)
12. Make-up (17 per cent)
13. Prescription glasses (13 per cent)
14. Books/e-reader (13 per cent)
15. Guidebooks (13 per cent)
16. Bank card (13 per cent)
17. Passport (12 per cent)
18. Travel insurance (12 per cent)
19. Maps (12 per cent)
20. Foreign currency (11 per cent)
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