How Big is the World?

Hi, am after a little help from #DungeonMasters. Looking to run an online game for friends during lockdown and wondered how many of you created your own world, and how deep did you go creating it? #ttrpg #DnD #dungeonsanddragons #RPG #DnD5e

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That is an excellent question, and it comes up often from new GMs watching my live-stream. The short answer for Twitter is cruxxed around a primary question; what is the fastest that power and news can move? The speed of military power and regional news is what restricts the speed of decision making and governance. In a very broad sense, everything else exists within that framework.

If you put a map of Europe & the USA side by side, you’re going to notice something. Europe’s total geographical area is about ten million square km; there are a 12+ major countries with 3000 years of history there. If you exclude Russia, the rest of Europe fits into Alaska

TTRPG Map Sadelyn Island from my Scattered Islands setting
TTRPG Map Sadelyn Island from my Scattered Islands setting

Why? Speed of communication. Look at the map of the USA. Compare Rhode Island, or even Maine, to Texas? As you go East to West, the size of political objects increases. Each increase is a “Tech Level”; horse, train, telegraph, etc.

So, the size of a political object — a “state” of some kind — is limited by the speed that the Borderlands (a.k.a. “the Marches”) can tell the Capitol / Seat of Governance they need soldiers NOW. Remember Gallieni’s famous Army By Taxi moment? That’s how fast the soldiers can respond to the problem.

So, your world is viewed by your players/characters based on the speed and ease by which they move through it.

From an Italy point of view, China is only interesting if you have a lot of time, or planes. Rome, Italy to Beijing, China is 5,062 miles / 8 147 km BY AIR. At 40 miles a day, for mounted Napoleonic troops, that’s 127 days. That’s presuming you can sort out that little detail of the Himalayas.

At a foot-march pace of ~25mi/day, you’re over 200 days, again, ignoring the mountains.

All that said, the original question … how big is the world? The most meaningful answer my experience has shown me is “three weeks wide”.

Once you have figured out how fast heavy cavalry and heavy wagon merchants can move, and it’s 3 weeks wide at that speed ON ROADS.

TTRPG Map - The Duchy of the Mists - My Homebrew Setting
TTRPG Map – The Duchy of the Mists – My Homebrew Setting

Create your initial basic map of major land forms based on an area 20% wider than this working distance. Don’t worry too much about anything beyond some basic biome concepts such as hills, forests, plains, swamps, lakes, rivers, coasts, etc.

Draw three circles towards the middle of the map, each a “week wide”, inside the larger “three week wide” space you’ve defined. Make sure the each circle touches at least one of the others. Over-lapping them by between 5% to 10% gives you areas of conflict; client states, active battle grounds, or “no-state-owns”.

Rivers will double the speed of travel; they also function as indisputable boarders. Forests or hills will halve the speed. Swamps and “Badlands” will quarter it. For simplicity right now, treat mountains and seas as walls.

Take those three circles you’ve drawn, and stretch them or compress them based on the terrain; stretch along rivers, compress areas along hills, forests, swamps and broken terrains.

The Capitol of a given state will usually be at the fork of a river at least 300m wide, & 3 days long. River should run to the sea or a great lake. The closer to the Marches you get, the smaller the settlements & bigger the forts, & rougher the company. The inverse is also true.

For new characters just starting out, that’s a vast world. That’s three different cultures to explore, learn, and either fall in love with or learn to hate.

So next, for each culture start bashing some broad brush-strokes that are the “stereo-types” that “everyone knows” about them. Here are some things that will immediately create distinction:

  • What foods do they love or hate?
  • Biggest form of art?
  • Popular style of music?
  • Common material & color of clothes?
  • When does their government change hands?
  • Are the national policies either “Expansionist” or “Interventionist”
  • Do they have an area of Trade Dominance, like the Germans had on optical glass?
  • Are most people happy?
  • Is slavery OK?
  • What are the 6 most common races; 60%, 30%, 15%, 7%, 3%, 3%.
TTRPG map for Lanogiannes home-brew setting

Make notes as you think new things up. Keep sharing details w/ your PCs, even if it’s ad-lib. Write it down; it’s real now.

Keep in mind that you don’t need to know all the answers for everything; until the PCs look, it doesn’t matter. Listen to your Players; they’ll say stuff like “it would be cool if this society did <blank>”. Make it so; they’ll feel smart for having “guessed” something and you’ll have less creating to do alone.

Often your players will see things as patterns that are actually “random noise”. For example, I random role genders for my NPCs; short version 1d8; 6+ is presenting femme for below age 40, 4+ for above age 40. One of my players stated “huh; I just realized every Paladin in a position of leadership we’ve met so far for this region has been a woman“. That was literally just dice talking and I’m pretty sure the total they’d met was three; however, as of that point, I made it part of the regional culture itself and came up with a reason why.

What about the rest of the world / dimension? Is there more beyond just this three-week bubble? Sure! Just keep adding chunks 3 weeks wide in whatever direction the Player/Characters are moving. For an “Earth-sized” space, the map wraps around at 8 000mi/12 000km.

That’s a whole world. Or at least the parts that are relevant to your players right now.

Most importantly, have fun!


Thanks very much for reading this post, and visiting my blog. I hope something I’ve said makes sense or is even helpful. You can catch up with me to talk TTRPGs and GM-ing via Twitter at , or most Sunday mornings on

Please feel free to leave comments or questions in the section below. I’d love to hear from you.

All the best, have fun with whatever you are playing, and I hope to chat with you soon.