Caps in Fallout 76 are used mainly for fast travel. You can spend them on stimpaks or ammo but in most cases, you'll use it for traveling between locations (if you don't want to go on foot every time). How to earn caps fast? On this page, you'll find three methods to effectively get them.
Selling the Mothman's Eggs
The first way allows you to earn 200 caps for each day in the real world. This number is due to the fact, that merchants in Fallout 76 own 200 caps which restores every 24 hours. Of course, you can visit all of the merchants in the game but in this method, you'll be using a merchant only from Flatwoods.
To do it, you have to go to the Mothman Museum - this place is located near the Vault 76 and Flatwoods. It's worth setting up a camp in the area of Flatwoods to teleport there and visit the merchant.
The method is to collect Mothman Eggs - they're shown in the picture above. They're scattered throughout the area but you'll find the biggest clusters of it by the river near the bridge or next to the statue of mutated moth. Collect all of the eggs and then restart the game to restore them - now you can collect them again.
How can you get caps that way? Collected eggs are worth a lot of money. You can sell one egg for 2 caps, and in the places mentioned above, you'll find about 20 eggs each time you log in.
You can earn even more if you cook Mothman Egg Omelette at the cooking station - you'll get 5 caps for one omelet. To prepare it you'll need one egg and one wood piece - you can use the wood collected thanks to our guide How to get wood?
Collecting 40 eggs and creating 40 omelets should be enough - sell them to the merchant. It won't take you that long if you build a camp next to Flatwoods. To get 40 eggs, you need to log out and log in while staying in the museum. Then, teleport to the camp you've built next to Flatwoods for free, go to a nearby cooking station and create 40 omelets. Lastly, go to the merchant in the white church and sell everything you have cooked. It will take you about 10 minutes to make 200 caps - provided that you've discovered the Mothman Museum.
Killing Super Mutants
Super Mutants are the best source of caps. Of course, you can earn money by killing enemies of different types (and selling their loot) but Super Mutants additionally can have some caps on them. Go to the place where Super Mutants appear e.g. AVR Medical Center, kill and loot them and restart the game - they will respawn (you can repeat this process until you get the desired number of caps).
Participating in events
Taking part in events is also a good way to earn caps. All of the currently available events are marked on the map as yellow hexagons - you can teleport there or go on foot. Events are special missions which require killing many enemies or repairing devices. This type of quests are focused on cooperation but it is possible to complete it solo. For every completed event you'll get a reward: ammo, food, medicaments or a dozen of caps.