Just a heads up the jeans will no longer have the "wear" marks. The jeans will be basically one color but not solid i will have small variations. Another thing to note is that the threads/stitching does not dye so that's cool. Most stitching uses polyester thread and will not dye. If you have cotton stitching that will probably dye.
Step 1: Materials
-1 box of rit dye navy blue (or denim blue)
-1/2 box of rit dye black
-3 gallon or so bucket
-Optional blue making/painters tape
You can get Rit dye from walgreens for like $3 but may be cheaper elsewhere. If you check the first picture it shows the difference in shades of color for denim vs. navy blue. Choose which one you feel is better. (Navy blue is a bit darker but more "blue") You can add the full box of black dye but obviously it'll be much darker and closer to black. I find half is a good amount. The size of bucket doesn't matter as long as it hold enough water to fill over the jeans. If you have levi's or other jeans with one of those papery tags on the back you can cover it up with masking tape. I have tried duct and packaging tape and so far blue painter's tape works the best.
YOU NEED GLOVES unless you want smurf colored hands...
Note: there is a way to dye your jeans using a big pot over the stove but that makes a mess in the pot and is INCREDIBLY hard to clean.
Step 2: The Dying Process
Before you start, PUT ON THE GLOVES! If the dye gets on your skin its really no big deal its just slightly difficult to wash off. BUT it is a pain. You want to get the water to as hot as possible before adding to the bucket. When it is, add your dye powder of 1 blue and 1/2 black. Add a good enough of HOT water to the bucket. You'll also want to drench your jeans with hot water as well. Try to make sure there isn't any dry spots because the dye might not affect that area well. Add your jean to the bucket and make sure there is enough water so that the jeans is kind of free floating. (Personally for my bucket its up to the 2 gal mark with the jeans in) I would "rearrange" the pair for the first five or so minutes so that it gets evenly dyed. Let it sit for about 30 min.
You could add more then one pair at a time but i feel that the dye wouldn't be absorbed well unless you add more water but that dilutes the system. This works really well for one pair of jeans and every pair of jeans after the first one will be a slightly lighter shade than the first.
Step 3: Drying
1) Just dry it. The jeans will be darker if you do this but it will most likely rub off on stuff.
2) Rinse THEN dry it. The jeans will be lighter but will most likely NOT rub off on stuff.
I generally rinse it because I wear a lot of white tees and I have a white couch. When rinsing, use COLD water. Hot water will rinse off too much. Just rinse it off until the water is pretty clear. Does not need to be exactly clear. Dry it with a method of your choice. I just put my jeans in the washing machine and set it to spin to get excess water out and then stick it in the dryer on the lowest setting.
Note: Apparently there's ways to "set" the dye with vinegar or something but I don't want my jeans to smell odd.