How to Tune a Guitar - Double Drop D

Double Drop D Tuning: D A D G B D

This is a fun tuning. It is known by several names including “Double Drop D” and “Double D Down”. It is identical to drop d guitar tuning, except that the highest E is also lowered to a D. Hence the Double D in the titles.  

Step 1: Lower the lowest E to D

I am assuming you have your guitar tuned in standard guitar tuning. Pluck the D string (4th) and the low E string (6th) in unison and then lower or loosen the sting, until the pitches are the same.

Step 2: Lower the high E to D

Use the 4th string (D) to get the right pitch. Loosen the peg on your thinnest string until the pitch is the same as the D.
You should now have three D strings: the sixth, fourth and first.

Strings	Standard	DA D G B D	Changes
6	E	D	Lower 1 Whole Tone
5	A	A	-
4	D	D	-
3	G	G	-
2	B	B	-
1	E	D	Lower 1 Whole Tone