Skip to content

HOI4 (Hearts of Iron IV): Best Combat Width Guide

HOI4 (Hearts of Iron IV) Best Combat Width Guide

Hearts of Iron IV (HOI4) is a captivating grand strategy game released by Paradox Interactive in 2016, focusing on the tumultuous era of World War II. Offering players the reins of a nation, it empowers them to shape the destiny of their chosen country and leave an indelible mark on history. While strategic decisions play a crucial role, the game emphasizes the significance of ground warfare, highlighting the combat width mechanic. This mechanic limits the number of troops that can engage in a single battle, emphasizing the importance of tactical deployment and force composition. In this article, we will delve into the intricacies of combat width in HOI4, providing insightful examples of effective strategies to optimize battle outcomes.

What is Combat Width in HOI4

Combat width is the size of your division in HOI4. Most battalions have a combat width of 2. Artillery, on the other hand, has three combat width. Anti-Tank and Anti-air battalions each have one combat width. Support companies are the only ones who do not have any combat width generated. All combat widths mentioned include motorized and mechanized versions as well.

The combat width of a battalion can only be reduced through the Mass Assault Land Doctrine (either tree works since both will give a 0.4 reduction to the combat width of a battalion). For now, no other method exists to reduce the combat width of battalions.

In HOi4 battles, combat width starts with a base value (depending on the terrain). This can be increased by attacking the province from multiple directions. Any unit that, if added to the battlefield, will exceed the combat width of the battle will remain in reserve until it can be called upon.

If one side exceeds the combat width of a battle, there will be penalties. The calculation goes like this: 1.5 * (total width minus battle width) / battle width.

It’s a good rule of thumb to remember that mountain and marsh terrains give the lowest base combat width in HOI4, while urban, plains, and desert terrains give the highest base combat width.


When a unit is in reserve, it does not deal any damage or take any damage to its organization. However, they can provide recon and anti-air abilities, but this is all they can do in the backline.

A unit in reserve starts off with a base chance of 2% to join the battle. You can increase this chance by researching radio, attaching a signal company to the division, researching doctrine trees, increasing the division speed, and assigning proper traits to the Field Marshal of the Army Group.

If defending, it is vital to have reserves ready to plug in the gap in order not to lose the area in question. When attacking, it may be wiser to stop an attack once all initial frontline units have been exhausted and launch another one right after with your fresh reserve units so as to allow all of them to join at once.

Best Combat Widths in HOI4

While each terrain has an ideal combat width to utilize, the most popular ones in HOI4, from lowest to highest, are 10, 15, 18, 21/25, and 41/45.

The advantages of each combat width in HOI4 are as follows:

  • 10: Best for garrisons and low-supply area. Their low combat width means a much more maneuverable unit and will ensure that all units in an army will be able to join a battle, should there be one
  • 15: The upgraded version of the 10 combat width, the 15 combat width is better at slightly more hospitable areas where enemies can easily resupply as opposed to the harder ones.
  • 18: The standard for the early game and mid-game, the 18 combat width is the bread and butter of all armchair generals. It allows for the standard 9 infantry battalions (which are great for defense) or 6 infantry and 2 artillery battalions (for light offense), both of which are key to any nation’s early victory.
  • 21/25 and 41/45: The best of the bunch for the late game. It would be nice to have the 41/45 since they pack more punch, but it’s better to keep an eye out on your manpower and the terrain, as having more troops will prove useless if they are unable to take part in the battle.

And that is all you need to know about best combat width in HOI4. Check out other interesting HOI4 guides and articles:

Based in Santa Rosa, Philippines, Jonathan Ledesma is a Freelance Writer for Raider King.
Jonathan Ledesma
Notify of
Inline Feedbacks
View all comments