The offer
American Express is running a 20% transfer bonus from Membership Rewards to Aeromexico Rewards for the month of October. Aeromexico is already one of Amex's richer partners at 1,000 points to 1,600 Aeromexico points; with the bonus, 1,000 Membership Rewards points become 1,920. The bonus is built into the ratio shown in your account, so it applies to every transfer during the window, not just the first.
The end date is the one detail the trackers disagree on. One Mile at a Time and Upgraded Points say October 31; AwardWallet and Frequent Miler say 11:59 p.m. Mountain time on October 30. Amex's own page is behind a login. Treat October 30 as the deadline and you cannot be caught out.
How the math works
Transfers go in 1,000-point blocks, from a minimum of 1,000 to a maximum of 999,000 per transfer. Amex charges a fee on transfers to US-based airline programs, but Aeromexico is a Mexican program, so no fee applies. Transfers are usually instant and always irreversible.
Our Membership Rewards calculator values a point at about 2.1 cents, and we put an Aeromexico Rewards point at around 0.8 cents. With the bonus you get 1.92 Aeromexico points per Membership Rewards point, so the transfer only pays if your redemption gets more than about 1.1 cents per Aeromexico point. That rules out most economy awards and favors business class.
Where Aeromexico points are worth it
Aeromexico prices awards by season, and the gap is wide. One Mile at a Time's example is business class between Mexico and North America from 36,000 to 52,000 Aeromexico points one way in low season, which is roughly 19,000 to 27,000 Membership Rewards points with the bonus. AwardWallet's long-haul example is Mexico City to Madrid in Premier One for 150,000 points, about 79,000 Amex points after the bonus. On high-season dates the same seats can cost far more, and Aeromexico passes on carrier surcharges, so check the cash total before you commit.
Two practical notes. Aeromexico's US website often hides the option to pay with points; searching on the Mexican site in Spanish usually shows it. And Aeromexico charges meaningful fees to change or cancel an award, so book only when the plan is firm.
How it compares
Amex has offered 25% to Aeromexico in past promotions, so 20% is a middling bonus by this partner's standards, though it has run at this level in both spring 2024 and spring 2025. It sits alongside a 25% bonus to Air France-KLM Flying Blue that ends on the same weekend, which we covered in our Flying Blue piece. Flying Blue is the more flexible program for most readers; Aeromexico is the one to pick for Mexico itself or for a SkyTeam seat that Flying Blue prices higher.
What to do
Price the exact Aeromexico award you want, in points and in the cash fare you would otherwise pay. If the points price lands in low season and the surcharges are modest, transfer only what that booking needs, in 1,000-point blocks, and book the same day. Leave the rest of your Membership Rewards balance where it is. A 20% bonus is a reason to use points you were going to use anyway, not a reason to move points you had no plan for.