Here is the full list of all 51 Red Dead Redemption 2 achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Earn 70 Gold Medals in Story missions.
Survive 3 days holding a bounty of $250 in all states.
Study every animal across all states in Story Mode.
Skin every species of animal in Story Mode.
Survive 18 bear attacks and kill the bear each time in Story Mode.
Find a permanent home for the squirrel statue.
Attain 100% completion.
Find the graves of each of your fallen companions.
Complete the Epilogue.
Complete 'A New Jerusalem'.
Complete 'Red Dead Redemption'.
Complete all optional Honor story missions.
Discover the fate of Marko Dragic.
Complete 'Goodbye, Dear Friend'.
Complete one of the Collectable strands.
Reach maximum or minimum Honor level.
Complete Chapter 5.
Complete Chapter 4.
Complete 10 Stranger mission strands.
Spend $5000 across all shops.
Complete a Companion Activity in each camp.
Red Dead Online: Purchase 5 camp improvements.
Red Dead Online: Craft 25 pieces of ammunition.
Red Dead Online: Concurrently own 5 horses.
Complete Chapter 3.
Play all mini games.
Craft 30 unique items in Story Mode.
Complete Chapter 2.
Deliver 5 camp companion item requests.
Red Dead Online: Successfully counter a rival Posse's Free Roam mission.
Rob or loot $250.
Red Dead Online: Form a Persistent Posse.
Red Dead Online: Achieve MVP 3 times (in a round with at least 4 players).
Recover the stash from 4 homesteads.
Upgrade each available component for a single sidearm or longarm weapon.
Red Dead Online: Accept 10 Free Roam missions from characters around the world.
Donate $250 to the gang tithing box.
Red Dead Online: Complete a Free Roam mission as part of a Posse with at least 2 members.
Red Dead Online: Reach Rank 50.
Complete Chapter 1.
Red Dead Online: Play 5 Free Roam Events.
Red Dead Online: Achieve 5 gold belt buckles from awards.
Catch a fish weighing at least 16 lbs (7.3 kg).
Red Dead Online: Craft 20 items (excluding ammo).
Red Dead Online: Reach Rank 10.
Reach max bonding level with a horse.
Red Dead Online: Sell 20 items to the Butcher.
Red Dead Online: Pick 25 Herbs.
Red Dead Online: Take part in a Series.
Red Dead Online: Complete the Intro.
Complete 'Enter, Pursued by a Memory'.