The American Express Blue Cash foreign transaction fee is 2.7%. Both American Express Blue Cash Everyday and American Express Blue Cash Preferred have that same foreign fee, applicable to any purchases processed internationally.
American Express offers cards that do not have foreign transaction fees, like the Premier Rewards Gold Card and The Platinum Card. The tradeoff here is their large annual fees. The only American Express cards with no foreign transaction fee and no annual fee are the Delta SkyMiles Blue Card and the Hilton Honors Amex Card.
American Express Blue Cash Everyday Foreign Transaction Fees & More:
Foreign Transaction Fee: 2.7%
Annual Fee: $0 for Blue Cash Everyday; $0 1st yr, $95 after for Blue Cash Preferred
Rewards Rate: 1% to 3% cash back for Blue Cash Everyday; 1% to 6% for Blue Cash Preferred
APR: 13.99% - 23.99% (V)
Keep in mind American Express may not be the best choice to take abroad due to lower international acceptance than Visa or Mastercard. While Visa and Mastercard are accepted in 200+ countries, Amex lags behind at around 160 countries. There are lots of credit cards with no foreign transaction fee on those other networks, too.