Disabled people in the UK and their families are estimated to have a spending power of £200bn
Access for disabled people on the High Street in Britain is "shocking", according to a government audit of more than 30,000 shops and restaurants.
Thousands of venues had failed to adapt their premises, with a fifth of shops excluding wheelchair users, experts found.
There are 12 million people in Britain with disabilities, with an estimated spending power of £200bn.
Businesses are "missing a trick" and must do better, ministers said.
Accessibility experts DisabledGo visited all of the 30,000 venues in person to assess them, in the largest ever audit of its kind in the UK.
They found a fifth of shops had no wheelchair access, only 15% of restaurants and shops had hearing loops and three quarters of restaurants did not cater for those with visual impairments.
When they asked leading chains directly for more information, only 4% of 105 national retailers responded.
Findings of disability audit
"Everyone deserves to be able to go Christmas shopping or enjoy a festive meal or drink with their friends or colleagues," said Minister for Disabled People Mark Harper, who commissioned the survey.
"This isn't just about doing what's right. Businesses are missing a trick by not doing more to tap into this market.
"A fifth of the British population has a disability and they and their households have a spending power of over £200bn. Improving accessibility is a no-brainer."
Barry Stevenson, chairman of DisabledGo and a former director of Marks and Spencer, said: "We are pleased that many retailers have invested significantly in improved accessibility in the last 10 years, but the majority are still not doing enough."
"It's entirely unacceptable for disabled people, their family, friends and carers, not to be able to access all high street shops and facilities."
"Disabled people are not asking the earth; just that management do what's reasonable and think more about how they can help disabled customers better.
"And that includes better communication about their accessibility online.
"It doesn't need to cost a fortune to do the right thing and it could be the deciding factor for disabled customers between you and a competitor."
The Equality Act of 2010 obliges organisations to make reasonable adjustments for disabled people.
Ministers previously put a value of £80bn on the spending power of people with disabilities. But this was re-calculated earlier this year to include friends and family of disabled people, not just disabled people themselves, resulting in the larger figure.