The single supplement is a premium charged to solo travelers when they take a room alone. The amount involved ranges from 10 to 100 percent of the standard accommodation rate. Accommodation vendors justify the charge as an appropriate business practice. Single travelers see the charge as price gouging at their expense. Discounts for booking early or repeat bookings and programs that arrange shared accommodation are variations on pricing that can ameliorate the single supplement for solo travelers. Research prior to travel may find companies that have removed the single supplement.   Being a solo traveler, if you prefer the privacy of your own room, you can opt for single supplement, though you may wonder why the provider did not offer sufficient single rooms in the first place.
Vendors and agents in the travel industry quote package-deal and accommodation prices in terms of dollars per person when the customer travels in a group of two, that is, "twin share" or "double". The single supplement is a premium surcharge applied to a traveler who travels alone but will use a room that caters for two.
Rationale for the single supplement
Arguments for the supplement are twofold. Firstly, solo travelers should pay for the luxury and convenience of having a room to themselves. Secondly, accommodation vendors must be compensated for the cost of preparing a room for a guest (cleaning and provision of disposables) when only one person will be charged. Providers also claim to perceive that couples are collectively likely to be more free-spending on facilities such as bar or casino than single persons, though evidence for this is anecdotal.
Objections to the single supplement
The solo traveler argues that traveling alone is often a necessity rather than a luxury and that the cost of preparing rooms for guests should be distributed among customers without discrimination, or (more extremely, but, as they would say, just as rationally) that couples should be surcharged for the privilege of not having to sleep apart. Solo travelers say also that tour suppliers deliberately under-cater for singles as compared with the proportion of singles in the general population, thus demonstrating that they are merely profiteering. 
Objections to the single supplement may be partly explained by the "framing effect" described by Nagle and Holden in 2002. This effect occurs when customers see cost as a combination of gains and losses. Take as example, a hotel room advertised at #£300, with a £25 discount for early booking and compare it with the same room at #£250, with a 10% single person surcharge. Customers will tend to choose the arrangement even though the cost of £275, is the same. Customers tend to choose gains over losses. An early booking discount is seen a gain, whereas a surcharge is seen as a loss. It is part of the skill of the provider to ensure that the losses to the customer exceed the gains.
Those affected may choose an accommodation vendor or tour operator which caters specifically for the solo traveler. Singles networks may assist in finding a compatible travel companion. Those affected may in turn regard this approach as insulting and patronizing. 
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-  Define Single Supplement
-  Single Supplement
-  What is the single traveler supplement?
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