American Express Membership Rewards is Delta's only major credit card transfer partner. Points earned in the program can be transferred to Delta SkyMiles at a 1:1 ratio.
Conversion Ratio
Membership Rewards Points can be transferred to Delta SkyMiles at a 1:1 ratio. This means that every 1,000 AMEX Points you transfer to your Delta account will give you 1,000 Delta SkyMiles.
Transfers from AMEX to Delta must be done in 1,000-point increments and you must have at least 1,000 AMEX Points to initiate a transfer.

Excise Tax Offset
Every time you transfer AMEX Points to a U.S. airline frequent flyer program, you will be charged an Excise Tax Offset of $0.0006 per point. This comes out to being $0.60 per 1,000 AMEX Points you transfer.
AMEX allows you to pay for the fee either in points or with an eligible Membership Rewards credit cards connected to the account. When paying in points, they will be worth 0.5 cents each which is a bad redemption value considering you can easily get 1 cent redeeming directly with AMEX or higher when transferring to partners (such as Delta).

I highly suggest paying with your credit card when transferring points.
Conversion Calculator
Use the Conversion Calculator to calculate the transfer of American Express Membership Rewards Points to Delta SkyMiles.
Excise Tax Offset fee for this transfer: $0.00
Learn more: Which Credit Card Points Transfers To Delta SkyMiles?
How to transfer AMEX points to Delta
Transferring Membership Rewards points to Delta SkyMiles can be done in a few easy steps.
1. Go to the AMEX website.
Go to americanexpress.com. Enter your login credentials, select "Membership Rewards" from the drop down, and click Log In.

2. Select Transfer Points.
Once you're logged in, scroll down to the "Ready To Redeem?" section and click on the tab that says Transfer Points. Click on View All.

3. Select Delta SkyMiles.
Find Delta SkyMiles in the list and click the column to expand it.
If you have never linked your Delta SkyMiles account to your Membership Rewards account, you will be asked to enter the Delta SkyMiles account number and select a card member. The name selected must match the name on the Delta SkyMiles account.

4. Choose the number of points to transfer.
Use the slider or manually enter in how many points you wish to transfer to Delta and select the Delta SkyMiles account you wish to transfer them to.
You can transfer a minimum of 1,000 points and a maximum of 999,000 points, in 1,000-point increments.
Click Review Transfer.
5. Review the transfer
Review the transfer to make sure that every thing is correct and click on Submit Transfer. Points will typically transfer within minute, but it can take up to 48 hours to see the balance reflected in your Delta SkyMiles account.
Ways To Earn More SkyMiles
With American Express Membership Rewards being the only major U.S. credit card transfer partner, there's not many additional options when it comes to earning a large amount of points outside of Delta's own co-branded credit cards.
Here are the full list of partners that you can use to earn Delta SkyMiles:
Learn more: Best Delta Credit Cards (+ SkyMiles Calculator)
FAQ
What's the transfer ratio of Membership Rewards points to Delta SkyMiles?
Every 1,000 Membership Rewards points you transfer to Delta will give you 1,000 Delta SkyMiles.
How long does it take for AMEX Points to transfer to Delta?
It typically only takes a few minutes to be reflected in your SkyMiles account, but could take up to 24 hours.
How much does it cost to transfer AMEX Points to Delta SkyMiles?
AMEX will charge you $0.0006 per point transferred to Delta SkyMiles. This means that every 1,000 points you transfer will cost you $0.60.
Delta SkyMiles calculators
Check out all of our Delta SkyMiles calculators and calculate everything from how many miles you can earn with credit cards to the cash value of your miles based on redemption!
These calculators and guides are all about maximizing your spending and earning the most SkyMiles per dollar spent.
Use our Delta credit card calculators to estimate how many SkyMiles you can earn and the cash value of the card based on the spend amounts you enter, how much you value benefits, and annual fees.
Our calculators allow you to compare up to two additional credit cards side by side based on same or different spend. Plus, all spend amounts you enter in the Primary card's column rolls over to all credit card rewards calculators on the site!
Reminder: Don't forget that you can also transfer credit card points from partners to Delta SkyMiles!
In need of more SkyMiles? You can transfer rewards from several partner programs directly to your SkyMiles account!

Want to know what you can redeem your SkyMiles for and how much they are worth? Check out our Delta miles value calculators.