Amex to Marriott 20% Bonus: Worth It Before June 30?

You log into your American Express account, glance at the transfer partners, and there it is: a 20% bonus to Marriott Bonvoy, flashing like a sale sticker. Suddenly 100,000 Membership Rewards points become 120,000 Marriott points, and your thumb hovers over the transfer button. Before you tap it, do this one piece of arithmetic. Amex is running this bonus on its US Membership Rewards programme from 1 June to 30 June 2026, and for most people it is a quietly terrible deal dressed up as a good one. There is exactly one situation where it makes sense, and a couple of traps that will cost you real value if you get it wrong.

What the 20% bonus actually is

The mechanics are simple. Through 30 June 2026, American Express is adding a 20% bonus when you move Membership Rewards points to Marriott Bonvoy. The standard ratio is 1:1, so with the bonus baked in you transfer at 1,000:1,200. There is no separate "register here" step and no cap you need to worry about for a normal stay, so you can use the elevated rate as many times as you like during the window. Transfers from Amex to Bonvoy are usually instant, which matters if you are racing to lock in a specific award before someone else grabs the room.

For context, this pairing sees a bonus roughly twice a year, typically somewhere between 20% and 35%. So at 20%, this is the weakest version of a promotion that was never particularly strong to begin with. "Better than nothing" is doing a lot of heavy lifting here. The headline number is designed to make you act; the underlying value is what should decide whether you do.

One complication worth flagging before we get to the maths: Marriott now uses dynamic award pricing. The same room can swing by tens of thousands of points depending on date, demand and how full the hotel is, and there is no fixed award chart to anchor against any more. That makes a "transfer now, decide later" approach genuinely risky, because the redemption you mentally penciled in at 50,000 points might price at 80,000 by the time you go to book. Every decision below assumes you have pulled up your actual dates and seen the real number, not an old chart figure or a rough guess. If you have not done that yet, you are not ready to transfer.

Why "20% more points" can still lose you money

Here is the part the banner does not show you. Not all points are worth the same, and Membership Rewards points are worth far more than Marriott points. Independent valuations put Membership Rewards at roughly 1.5 to 1.7 cents each (about 1.2p to 1.3p), while Marriott Bonvoy points come in at only about 0.7 to 0.8 cents each (roughly 0.6p). That gap is the whole story.

Run a realistic example. Say you transfer 50,000 Membership Rewards points to capture the bonus. You receive 60,000 Marriott points. Those 50,000 Amex points were worth around $750 (about £590). The 60,000 Marriott points you got back are worth around $460 (about £365). You have just converted roughly $290 of value into nothing in exchange for the convenience of having Marriott points. Put another way, even with the 20% sweetener, each Membership Rewards point buys you only about 0.8 to 0.9 cents of hotel value, despite being worth nearly twice that in your Amex account. A 20% bonus does not rescue a transfer that starts out destroying half your value.

This is why the consensus among award-travel analysts is to skip it. The bonus is real, but a bigger pile of weaker currency is still a worse pile. If your instinct is "points are points," this is exactly the instinct the promotion is built to exploit.

It gets worse when you consider the alternatives. If you genuinely need Marriott points and have a stay in mind, Marriott itself runs regular "buy points" promotions that land the cost at roughly 0.9 to 1.0 cents per point. Buying the points you need with cash, while keeping your Membership Rewards intact for a flight redemption worth 1.5 cents and up, is frequently the smarter move. In other words, the question is not only "is this transfer a good deal" but "what else could those Amex points do." Almost always, the answer is "considerably more if they go to an airline." A transfer bonus should make you reach for the points, not reach past every better option you have.

The one time it genuinely makes sense

There is a legitimate use, and it comes down to a single word: topping off. If you have already found a specific Marriott redemption, priced it, and you are short by a small margin, then transferring a modest number of Amex points to complete the booking can be perfectly rational. The logic flips because you are no longer valuing Marriott points in the abstract; you are buying a known, high-value stay you would otherwise miss.

Marriott's fifth-night-free benefit is what makes the best of these stays sing. Book five consecutive nights entirely on points and Marriott charges you for only four, an automatic 20% discount on longer redemptions. Crucially, the whole stay must be on points to qualify; mix in a cash night or a free-night certificate and you forfeit the perk.

Imagine a property pricing at 60,000 points a night. Five nights would be 300,000 points, but with the fifth night free you pay 240,000. If the cash rate is $600 a night, you are extracting $3,000 of accommodation for 240,000 points, which works out to about 1.25 cents per Marriott point, comfortably above the baseline. If you are 30,000 points short, transferring 25,000 Membership Rewards points to finish the booking is defensible, because those Amex points are unlocking value of around 1.5 cents each rather than sitting idle. The rule of thumb: only top off when your specific redemption clears roughly 1.1 to 1.3 cents per Marriott point or better. At the rare top end, well-chosen luxury redemptions can exceed three cents per point, and there the maths is obvious. Those are outliers, not the norm.

The back-door-to-airlines trap

Every transfer bonus season, someone reinvents the idea of laundering Amex points into airline miles by routing them through Marriott. It almost never works, and it is worth understanding why so you do not talk yourself into it.

Marriott converts points to airline miles at a 3:1 ratio, and for every 60,000 points you move it adds a 5,000-mile bonus. So 60,000 Marriott points become 25,000 airline miles with most partners. United MileagePlus is the standout exception, granting a 10,000-mile bonus per 60,000 points, while American AAdvantage, Delta SkyMiles and Avianca LifeMiles get no bonus at all.

Now chain it together. Transfer 100,000 Membership Rewards points and the 20% bonus gives you 120,000 Marriott points. Send those to most airlines and you land around 50,000 miles; even to United, the most generous partner, you get about 60,000. The problem is that Amex already transfers to most of those same airlines directly at 1:1. You would have turned 100,000 Amex points into roughly 50,000 to 60,000 airline miles, when a direct transfer would have given you 100,000. You have halved your stash to take the scenic route. The only time the detour is worth considering is for an airline that Amex does not partner with but Marriott does, paired with a redemption you have already confirmed is exceptional. For everyone else, transfer to your airline of choice directly, and if you want to compare what a given award is really worth, sanity-check the numbers with Pointsbot's points assistant before you move anything.

Pro tip: Reverse the order of operations. Find and price the exact award you want first, then transfer only the points you need to complete it. Speculative transfers, made because a bonus is "ending soon," are how perfectly good Membership Rewards points get trapped as a depreciating hotel currency you never quite spend.

Your action plan before 30 June

If you are tempted, work through this quick checklist. First, confirm you have a real redemption in mind, ideally a five-night, all-points stay that benefits from the fifth-night-free discount. Second, price both the points cost and the cash rate, and check the value clears about 1.1 to 1.3 cents per Marriott point. Third, transfer only the shortfall, in 1,000-point increments, and remember the transfer is usually instant, so there is no need to move points "just in case." Fourth, if the redemption does not clear that bar, leave your Membership Rewards points where they are; they are almost always more useful transferred to an airline partner or held for a stronger promotion.

A note for UK readers: this specific 20% bonus runs on the US Membership Rewards programme, so it may not appear in your account. The framework still applies to everything you do see. When a 30% Avios bonus or a Virgin Points promotion lands, ask the same question you would ask here, namely what the destination currency is actually worth to you, not how much bigger the number gets. A bonus only earns its keep when the points are heading somewhere you will genuinely redeem them for outsized value.

The bottom line

The Amex to Marriott 20% bonus is a textbook example of a promotion that feels generous and usually is not. With Membership Rewards points worth around 1.5 to 1.7 cents and Marriott points worth about 0.7 to 0.8, even a 20% boost leaves you giving up roughly half your value on a speculative transfer. The honourable exception is topping off a specific, well-priced redemption, especially a five-night stay where the fifth night is free. So before 30 June, do not chase the bonus. Find the stay, run the maths, and move only the points that booking actually requires. That is how you stay on the winning side of a deal designed for you to lose.