This is a basic guide on how to convert your real-life capabilities into D&D stats.
Before we begin, let me warn you: You will probably not like what you see when you do this. We are a bunch of lazy, good-for-nothing, privileged, opportunistic slugs. We are not superheroes, we're cashiers and truck drivers. We live in a safe, simple, easy, technologically advanced, modernized society, with widespread literacy. The fact that you are reading this at all is evidence that you are not the typical D&D commoner. You do not spend your days working the land under the blazing sun with wooden hand tools. You do not spend your nights cowering in a barricaded house hoping a 10-ton monster doesn't try to eat you while you sleep. You do not spend your winters chopping fire wood multiple times a day just to avoid a freezing death. Face it: Compared to the people we tell stories about, we are talking jell-o cups.
Unless you're a professional tough guy. Actual soldiers and stuff will probably get some pretty fantastic scores here.
You have been forewarned.
Initial Scores
The first step is to generate some raw numbers for each of the 6 abilities. These will require a combination of actual experimental testing and generic guesswork. As you're going, keep in mind that these will not be your final numbers.
STRENGTH
This is the easiest one. Lifting strength is 30lb. per 1 point of strength score. Go lift weights from the floor to over your head. Start with the smallest and work your way up in intervals of 30lb. The last one you're able to lift is your STR score.
Chances are, almost all people will be sorely disappointed and confused. Here's the deal:
You are a modern human who does not use their body in the extreme just to survive the day. D&D commoners live a hard, rough life- they live in a medievalesque age with limited technology and rare access to magic. They will obviously be tougher than us- we have grown soft due to technological comfort.
The exceptions to this are people who have actually trained their body for strength, such as fire fighters, soldiers, police officers, martial artists, and people who just like exercising a lot.
I can lift 90lb.. I can't lift 120lb.. With a score of 4, my light encumbrance threshold is 20lb. I can't imagine walking around with 20lb. of stuff on my back all day. But I think I could probably do it for a while.
DEXTERITY
Buy a dart board. Throw 20 darts at it. Try your hardest to hit the center red dot. Average out your results to determine where you hit mostly. Compare to the following chart.
Center 18
Center Ring 16
Middle Pie 14
Middle Ring 12
Outer Pie 10
Outer Ring 9
Score Ring 7
Wall 5
Floor 4
Foot 3
Additionally, if you can do any of the following, adjust your score as denoted. (Limit of 20)
Juggle +1
Card Tricks +1
Hand Stand +1
Back Flip +1
Splits +1
Balance On A Rope +1
Spin A Basketball On Your Finger +1
I hit all over the place, including the wall. The median appears to be the outer pie and inner pie area.
CONSTITUTION
Maybe I was wrong. This is the easiest one. Hold your breath as long as you can. The number of minutes you can go before losing consciousness is your CON bonus. (Add 1 minute to the end of where you gave up and started breathing again.) Chances are, you won't make it past 30 seconds. Your score is almost certainly 10.
In addition to your estimation, consider how often you get sick and how severe it is when you do. For example, I get sick pretty regularly, generally once every fall and once every spring. It starts as a sinus infection and over the course of a month and a half it works its way down my throat into my lungs, leaving me coughing for weeks after the infection itself has actually ended. My constitution is poor.
Another means of measuring constitution is your resistance to the effects of alcohol. Alcohol is a form of poison. Each time you drink alcohol, you are essentially making a save against the poison condition. The DC increases for each beer you have. So, how many beers can you drink before you can feel that you are drunk? Just a few? Probably a poor CON score. You can black out without feeling drunk? Probably a fairly high one.
I can go about 3 shots of whiskey before I feel it. Depending on the whiskey.
INTELLIGENCE
This is a difficult thing to gauge. We're going to go with the strictest interpretation of intelligence though: academic information retention and regurgitation. Go look at your grades from high school and average them together. Compare to the following chart.
A+ 20
A 19
A-18
B+ 16
B 14
B- 12
C+ 10
C 9
C- 8
D+ 7
D 6
D- 5
F 4
I'll be honest: I was a shit student. I did the bare minimum to pass and get by. I aimed for over 50%. Between my best grades and my worst, I average about 60%.
WISDOM
The only tangible thing this ability score represents is how perceptive you are. This is a massive abstraction. You're going to have to wing it on this one.
Here's a thing though: If you are constantly forgetting stuff, are easily spooked, often mistake tall objects for people, can never find important things you just had in your hand a second ago, and in general stumble through life as though you're on your way to developing Alzheimer disease... your score is probably 10 or less.
If you could actually do those wacky "magic eye" things and notice slight of hand in magic tricks, it's probably pretty high.
I am the jumpiest, most addled person you will ever meet.
CHARISMA
Charisma does not represent anything measurable at all. Again, you're going to have to guess at how charismatic you are! Here are some tips though:
If you are a musician or performer of any sort, you almost certainly have a score over 10. If you actually make money performing, you definitely have a bonus. If you successfully make your entire living off of your performance, your score should provide a +3 modifier or higher.
If you can actually haggle prices in our modern age, you definitely have a positive modifier.
Count up your friends. Your real friends. The close ones who would come to your aid even if it was inconvenient for them. Charisma is associated with being extroverted and influential. The more friends you have, the more charismatic you probably are. Likewise, count up the number of people you think of as enemies. Even if they don't think that way about you, the fact that such an idea/attitude is in your head indicates that your charisma may be lower than you think.
Consider how many relationships you've been in, and also how long they generally last. Consider how your relationships tend to end as well.
Consider how hard it is for you to get work. Do you get job offers on the first interview for multiple locations? Do you go for months without even getting a call?
Consider how involved in society you are. Do you volunteer? Are you part of any social clubs or groups? Are you part of a sports team? Do you participate in town hall meetings? Do you go to public events? Do you vote? Do you pay attention to the local news? Do you make charitable donations? Do you just sit at home watching entertainment television while the world passes you by?
How culturally aware are you? How many friends of differing ethnicity, gender, sexual orientation, faith, economic condition, education level, political affiliation, etc. do you have? How often do you travel? What is the most distant place you have traveled? Do you speak multiple languages? Do you watch foreign media or enjoy foreign food? Do you say your country is the greatest in the world even though you've never even left your home city in your life?
I used to have a lot more friends than I do now. I didn't bother to maintain those bridges. I have traveled, but very little. I am not involved in my community at all. I've been in few relationships, and the ones that ended, ended fast. I am an artist, but I don't make money off it. I really struggle to find work when unemployed.
Refining the Scores
For this part, you're going to need a group of players who are engaging in this exercise together. Each player will estimate what they think each other player's stat array should look like based on their opinions of that person's capabilities. Next, each player averages the results of the different estimates together. Finally, you average the combined estimate with your initial stats. The final array is your character.
People are too nice.
This step exists so that your character "feels right" to the other players at the table, such that what your character can do seems like something the other players think you might be able to do, even if it's technically not true. In essence, this is to achieve believability rather than actuality.
My Stats
STR 4 (-4)
DEX 8 (-1)
CON 8 (-1)
CHA 6 (-2)