The number of converts to Islam may have risen from around 60,000 in 2001 to up to 100,000, according to estimates in a report for the Faith Matters organisation.
A study by Kevin Brice, of Swansea University, on behalf of Faith Matters, found 5,200 people converted to Islam in the UK last year.
A survey of 122 converts last year showed 56% were white British, with women making up 62% of respondents. The average age at conversion was just over 27.
The majority of the converts saw themselves as both British and Muslim and did not feel disillusioned with British society and culture. A majority said that most or all of their close friends were Muslims and almost all felt that Muslims should not keep themselves separate from non-Muslims.
The vast majority of women had changed their appearance after conversion, with a significant majority adopting the hijab, or headscarf.
The findings have been released after Lauren Booth, sister-in-law of former prime minister Tony Blair, attracted widespread publicity when she announced last year that she had converted to Islam.