With the addition of the 1.11 Barbarossa update to Hearts of Iron 4, Paradox has changed how the game will work forever. When HOI4 first came out, Supply wasn’t really a thing many thought about.
However, with the addition of Supply Hubs and Railways, the mechanics of the game have changed forever. Nobody can just push into a country with their troops however they want. You will need to always keep an eye out for Supply Hubs.
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The problem is that the Supply system is very complicated and there are many players that will likely have problems with understanding it when they’ve just started playing. Especially since there are many working parts that you won’t really understand until your army starves once or twice.
To help you from making some of the most basic mistakes in Hearts of Iron 4, here is a complete guide for how Supply works in the game and how to manage all the Hubs and Railways.
Table of Contents
How Supply Works in HOI4
Supplies aren’t actually an item or equipment you can produce in the game.
Supplies are a resource that appears in your states based on various factors, such as state population, Infrastructure, Victory Points, and connection through Hubs.
All divisions in the game have a Supply consumption stat that decides how much Supply they need, which you should provide, otherwise their Organization will lower, making them easy to destroy.
There are two main sources of Supply in all provinces: State and Hubs.
The State Supply is the amount of Supply a province will get based on population, Infrastructure, and Victory Points. Supply from Hubs is the amount of Supply a province will get based on its connection to the capital.
The capital of your country has a main Supply Hub, the Capital Hub, that sends Supply to all the Hubs in the country through Railways.
The maximum amount of Capital Hub Supply (the Supply Cap) is based on the number of factories in the country.
This does not mean that the Supply Cap in your capital is how much supply you can send to all the Hubs. It is just a number that represents the maximum Supply you can have in all your Hubs.
Based on the Railway level, the other Supply Hubs have a maximum level of Supply they can provide as well.
Supply Basics
To make this easier for beginners, here’s how Supply works in HOI4:
The Capital Hub has a Supply Cap. Connecting the Capital Hub to a Supply Hub will give the Supply Hub a cap either based on the Railway level between them or on the Capital Hub’s Supply Cap.
The Supply Hub will provide the necessary Supply to the divisions in the area. If the overall Supply use of the divisions in the area around the Hub is larger than the Hub’s cap, they won’t be able to get all the necessary Supply.
Also, Railways don’t give troops any Supply, so building a Railway to a province without any Supply won’t help.
Supply Map Mode
Players can see all of their Supply requirements and general Supply production using the Supply Map Mode, which can be opened up by pressing F4 on the keyboard.
This Map Mode will show the locations of all the Supply Hubs, the paths of all the Railways, and the amount of Supply in all provinces of the country.
The color of the provinces will vary from bright blue to red, which represents the amount of Supply in them. Here is what each color means in the Supply Map Mode:
- Bright Blue – more than enough Supply
- Dark Blue – very low Supply
- Reddish Purple – almost no Supply
- Yellow – almost no Supply but enough to partially Supply the troops in the province
- Red – no Supply to provide the troops in the province
Based on these colors, players can generally figure out where they should build new Supply Hubs, where to increase the level of the Railways, and what regions the army should always avoid.
Supply Use
All divisions in HOI4 have a Supply use stat. If you were to open the Supply Map Mode, you would see exactly how much Supply each division is using in any province and how much they can get in those provinces.
One of the most common mistakes is putting too many divisions in a region with a weak Supply Hub.
If the cap for a Supply Hub is 14 and you place, let’s say, 20 divisions there, all with around 1 Supply use, they will all get debuffs due to passing the Supply cap needed.
Another important thing is to look at the Supply in a region before sending troops there. A frontline with a country might have provinces with 20 Supply and some on the outskirts with 2 Supply.
Either micromanage and make sure that divisions with low Supply use are stationed in that province or increase the overall Supply in the region.
How to Manage Supply
There are four ways to increase and manage the Supply in a state or province in HOI4:
- Increase Motorization Level
- Increase Railway Level
- Build Supply Hubs
- Increase Infrastructure Level
How Motorization Levels Work
All Supply Hubs in HOI4 have a range that they can Supply. This is generally decided by the Motorization Level. The Motorization Level just decides if you are going to use Trucks to Supply the troops or if you are going to use horses.
There are three Motorization Levels that players can change at any time:
- Horse
- Trucks
- Many Trucks
The horse supply option is enabled by default for all Supply Hubs and armies at the start of the game, and the AI will usually mainly use this one. This just means that all Supply Hubs will provide Supply in a small range around the Hub.
Changing the level of use of Trucks will increase the range that the Hub supplies while also increasing the amount of Supply in the provinces it was already reaching. However, you will start using Trucks in your Logistics to constantly provide this Supply.
The final level just doubles the results of the previous one, but will also use double the amount of Trucks for the job.
There are two ways to make sure that armies get more Supply using Motorization Levels:
- Increase the Motorization Level in a Supply Hub
- Increase the Motorization Priority of the army
Clicking on a Supply Hub in the Supply Map Mode will make three bubbles appear. The one on the right represents the Motorization Level. Click on it to toggle a different Motorization Level based on the icon shown.
The easier way to do this, which can often actually ruin your economy, is to set that your whole army should get a higher Motorization Level wherever the troops are.
You can do this by either selecting an army or an army group and pressing the horse button that appears over the weight of the army (the icon with a boat on water) in the upper left corner of the screen.
Railway Level
A Supply Hub’s cap is based on the Railway level between the Hub and the capital. Sometimes, the biggest problem an army can face on the frontlines is the Hub reaching its cap due to too many divisions present in the area.
This can usually be fixed by increasing the level of the Railway. An easy way to do this is to open the Supply Map Mode, press the Supply Hub in question, and press the Upgrade Bottlenecks button that appears in the middle.
Doing this will make sure that the Railways between that Supply Hub and the capital are either all on the same level, which would otherwise create bottlenecks, or increase the overall level of all the Railways between them.
Also, if you conquer a new Supply Hub and it says that it doesn’t have Supply, the most common problem is that it isn’t connected to the capital. Build a Railway from the Supply Hub to any of the Railways in your country around it to connect it to the Supply network.
Build Supply Hubs
Very often, the main problem is that the distance between Supply Hubs is too big. This can only be fixed by building new Supply Hubs from the Construction menu.
The only problem with this is that Supply Hubs take ages to build, and it will take most players years to get one done.
The best solution to this problem is fixing your Supply network and building all the necessary Supply Hubs at the start of the game after enabling the Reorganize the Railway System decision that most countries have access to.
This will speed up the process and allow you to build three Supply Hubs three times faster than normal.
Infrastructure Level
The last method to increase Supply in HOI4 is to build Infrastructure in states that have Supply problems. Each Infrastructure level will give the provinces in the state 0.3 Supply.
This means that provinces in that state, at the maximum level of Infrastructure, will get 1.5 Supply for free, without the help of any Supply Hubs. This will be extra Supply that will be taken before the one from the Hubs.
That’s everything you need to know about how Supply works in Hearts of Iron 4!
Have any input or suggestions for this guide? Let us know in the comment section below.
