What is postage on a regular letter USA to UK?

As of my knowledge cutoff date in February 2021, the postage on a regular letter (up to 1 ounce) from the United States to the United Kingdom is $1.20.

Please note that postage rates may change over time, so it is advisable to consult the United States Postal Service (USPS) website or your local post office for the most up-to-date information on international postage rates.