Hearts of Iron IV Production Guide: Factories, Resources, and Trade

Industry wins wars in Hearts of Iron IV. Your divisions, planes, and tanks all come out of the same pot of factories, and the country that runs that pot better usually comes out on top. The catch is the game explains almost none of it. You get three factory types, seven strategic resources, an efficiency bar, and a construction queue, then it kind of waves at you and walks away.

So here's the working setup, piece by piece. Numbers below come straight off the game's wiki, so you can trust them in your own campaigns.

Civilian vs Military Factory Ratios

What each factory type actually does

Civilian factories build things. They're what constructs new buildings, repairs damage, buys resources off other countries, and pays for production licenses. Each one puts out 4 construction points a day, or 5 when it's powered with coal from the newer energy system. A chunk of them also gets eaten by consumer goods, which we'll get to.

Military factories make equipment. Guns, artillery, tanks, planes. They sit at a base output of 3.5 a day (4.5 powered), multiplied by factory output modifiers and by that line's production efficiency. Naval dockyards are the third type, at a flat 2 a day (2.5 powered), and they only build ships, convoys, and subs.

A civilian factory costs 10800 construction points. A military factory costs 7200. A dockyard runs 6400. That price gap is why the order you build them in matters so much.

When to flip from civs to mils

A new civilian factory takes a while to pay for itself, but after that it's pure profit forever. The wiki has the actual payback numbers at 4/5 infrastructure and 0% construction speed modifiers:

| Economy law | Payback time (days) | | --- | --- | | Civilian Economy | 1143 | | Early Mobilization | 1067 | | Partial Mobilization | 1000 | | War Economy | 942 | | Total Mobilization | 889 |

Notice how brutal Civilian Economy is. That law hits both civilian and military factory construction speed by 30%, so everything you queue up crawls. Getting off it is usually your first big political power spend.

For the switch date itself, the wiki gives a formula: switch time equals your target war date minus about 2.9 times your payback time. Their worked example says a payback of 800 days with a January 1944 target means you should stop building civs around September 1937. That lines up with what most people actually do as Germany, where the community consensus from testing puts the civ-building phase somewhere in mid to late 1937, with early 1938 still being a solid choice.

Country by country

Who you're playing changes the answer a lot.

• Germany: civs until mid or late 1937, then all mils. You fight early and often, but you also grab Polish and French industry, so you don't need a giant head start.
• Soviet Union: you've got until June 1941, so civs into late 1937 or early 1938 works fine. You have room to build a big base first.
• United States: starts on Undisturbed Isolation, which craters factory construction speed by 50%. Climb out of that law first, then build civs hard. Your entry date is late enough that a fat economy pays off big.
• Poland, China, anyone who gets attacked in 1936-1939: skip the civ phase, for the most part. You need guns on the shelf before the war shows up, not a payoff in 1943.

One more thing on consumer goods. That number is a percentage of your total factories, military ones included, and those civs are unavailable for anything else. Civilian Economy demands 35%, Total Mobilization only 15%. Dropping the law doesn't just speed up construction, it frees civs you already own.

Managing Resource Shortages and Trade Deals

The seven resources and what they feed

Steel goes into almost everything: infantry weapons, artillery, tanks, ships, trains. Aluminum is for aircraft and support equipment. Rubber feeds planes and motorized or mechanized units. Tungsten shows up in artillery, anti-tank guns, and medium or heavy tank weapons. Chromium is for the fancy stuff, so heavy and modern tank chassis, battleships, carriers, and jets. Oil doesn't build anything directly, it gets refined into fuel that planes, ships, and vehicles burn. Coal is the new one, and it exists to power your factories for that output bump.

Resources can't be stockpiled. Whatever your factories don't consume that day is gone, so oversupplying doesn't help you at all.

What a shortage actually costs you

Here's the mechanic most new players miss. Running short doesn't just slow a line a little. Every missing unit of a resource adds a 5% output penalty, and it stacks per resource type, all the way to -100%.

The penalty lands on your lowest priority production lines first, and it hits individual factories in order. The wiki's example: with 2 steel and 0 aluminum available, and 11 military factories on support equipment, the first factory takes -5%, the second -10%, and it keeps climbing until the last factories sit at -100% and produce nothing at all. The line card showed an average of -50%.

So when you're short on steel, it's not "everything is slightly slower." It's "the stuff at the bottom of my production list has stopped existing."

Buying what you need

Trade is simple on the surface. One civilian factory buys you up to 8 units of a single resource, and that factory gets handed to the seller for as long as the deal runs. They can build with it, count it for focus requirements, or trade with it themselves. Even if the seller only has 3 units of tungsten left, you still pay the full factory.

Your trade law decides how much of your own extraction gets thrown onto the world market:

| Trade law | Resources to market | Factory output | Construction speed | | --- | --- | --- | --- | | Free Trade | 80% | +15% | +15% | | Export Focus | 50% | +10% | +10% | | Limited Exports | 25% | +5% | +5% | | Closed Economy | 0% | none | none |

That Free Trade row is why it's often worth keeping even when it means rivals can buy your steel. The output and construction bonuses usually beat what you lose, at least until the war starts and you'd rather starve everyone else.

Puppets are the real cheat code. A collaboration government or Reichskommissariat sells you 80 units per civilian factory instead of 8. That's ten times the value, and it's why annexing everything directly isn't always the right call in a peace deal.

Watch your convoys too. Overseas trade needs them, and subs will chew through undefended routes. If the sea lane dies, you keep paying the factories and get nothing shipped. Land routes avoid all of that, so a neighbor with resources is worth more than a distant one.

Fixing a shortage without trade

Trade isn't the only lever, and sometimes it's the worst one. Each level of infrastructure in a state adds 15% to its extracted resources, so 5/5 infrastructure is +75%. Each excavation tech adds 10% across everything you pull out of the ground. A state with a supply hub or naval base linked to your capital gets another 20%. And synthetic refineries (14500 each, max 3) crank out 1 to 5 rubber plus fuel, which is a lifesaver for Germany or Japan when the rubber runs dry.

Building Efficiency and Production Lines

The efficiency bar

Every military production line has its own efficiency. New lines start at 10% and climb toward a cap of 50% by default. Growth is fast early and drags near the cap, anywhere from about 1% a day down to 0.05%. Worst case, a line takes 500 days to fully ramp.

The machine tools techs each raise the cap by 10%, all the way to 100% at the 1943 techs. Those are quietly some of the best research in the game, because a line at double efficiency is a line that's twice as good without you building anything.

Dockyards ignore all of this. They produce at a flat rate no matter what, which makes them the one factory type you can reassign on a whim.

Retention, or why switching lines hurts

Change what a line builds and you lose most of its efficiency. How much you keep depends on how big the jump is:

| Switch | Efficiency kept | | --- | --- | | Different variant of the same model | 90% | | Different model on the same chassis | 70% | | Direct upgrade or downgrade of the same type | 30% | | Indirect upgrade or downgrade | 20% | | Anything else | 10% |

That's why you upgrade Infantry Equipment 1 to 2 and keep 30%, but jump from rifles to artillery and keep 10%. The Dispersed Industry techs and the 1943 Flexible Line tech pad these numbers, and the bonus applies to the loss rather than the keep, so it helps most on the worst switches.

Adding factories to an existing line is safe. The new ones start at minimum efficiency but the factories already there keep theirs. Losing factories is the reverse, cuts come off the bottom of the list, so drag your important lines to the top of the production screen where they're protected.

Concentrated vs Dispersed

After Basic Machine Tools in 1936 you pick a branch, and it's a real choice. Fully researched, Concentrated gives +75% factory output. Dispersed gives +50%, plus 50% production efficiency retention, 25% higher base efficiency, and 55% less bomb vulnerability.

Rough rule from the wiki's own comparison: Concentrated produces more after about a year to a year and a half on the same line. Dispersed wins in the first year of a new line, the first two or three years on a line you've switched to an upgraded model, and any time someone is bombing you. If you're a minor that retools constantly, or a country under air threat, Dispersed is the safer bet. If you're the US quietly building the same rifle line for five years, Concentrated prints.

Conversion, the free lunch

With the right DLC you can convert old equipment instead of scrapping it. Converting captured tanks or outdated airframes to a new variant costs no efficiency loss and often fewer resources than building fresh, since you only pay for what the new design needs beyond the old one. Turning a bare-bones tank hull into a full tank destroyer this way can cost a fraction of building it outright. It's worth checking before you delete that pile of captured Polish equipment.

Prioritizing Equipment for Your Divisions

Reading what a division actually costs

Divisions don't get built as units. Factories make equipment, and battalions pull from that pile. An infantry battalion needs 100 infantry equipment. A line artillery battalion needs 36 artillery pieces plus 500 manpower. Support companies each pull their own gear, engineers and hospitals and recon all draw from support equipment.

Run the math on a standard 9 infantry, 4 artillery division with engineer, support artillery, and recon supports. That's roughly 900 rifles, 144 guns, plus support equipment and trucks. Now multiply by the 40 or 60 divisions you want. Suddenly that rifle line eating 15 factories makes sense.

What to build first

Priority order matters twice over. It decides who gets equipment when stockpiles run short, and it decides which lines eat the resource penalty when you're missing steel or aluminum.

1. Infantry equipment always. Everything else is decoration if your line infantry has no guns.
2. Support equipment, since almost every division wants engineers at minimum.
3. Artillery, the cheapest soft attack in the game per factory.
4. Trucks and trains once supply starts mattering, which is always, thanks to the supply system.
5. Fighters, because air superiority decides half the war before ground troops move.
6. Tanks and specialty gear last, once the basics are covered.

That's a general template though, not gospel. A Germany pushing a 1940 armor spearhead shifts tanks up. A China holding with pure infantry can skip tanks entirely for years.

Licenses and the low-efficiency trick

You can license foreign equipment with civilian factories. Base cost is 1 factory for 1936 or older tech, plus one more factory per year beyond that. Improved Artillery from 1939 costs 4 civilian factories a pop. Licensed gear takes an output penalty, 25% from a faction member and 35% from anyone else, so it's a bridge rather than a plan.

Here's a trick worth stealing from the wiki. Production efficiency growth doesn't care whether the line has resources or not. So start a new line early, even if you can't feed it yet, and let the efficiency bar climb while you sort out trade deals. You eat almost no real loss, since an unfed line wasn't producing much anyway, and the line is warm when the resources show up.

Also keep an eye on the little indicator showing whether a line is sending gear to reinforcements, upgrades, or stockpile. Upgrading fielded divisions to newer equipment burns stock quietly. If you're staring at a war in three months, locking upgrades for a bit can be the difference between full divisions and half-empty ones.

Balancing Infrastructure and Construction Queues

What infrastructure buys you

Infrastructure costs 6000 per level, five levels max, and each level does three jobs in one state. It speeds up all construction there by 20% per level, so 5/5 doubles your build speed. It adds 15% to the state's resource extraction. And it helps supply, division speed, and organization recovery on top.

That construction bonus is why the classic opener is infrastructure first, then factories on top of it. A state at 3/5 infrastructure builds 1.6 times faster than one at zero.

But it's not free money, and the wiki has break-even numbers for it. Level 1 infrastructure needs about 36000 points of other buildings in that state to pay off, which is 5 military factories. Level 5 needs 60000, or 8 and a third military factories. Under that threshold you're better off just building the factory. So raise infrastructure in your big industrial states, not your rural ones with two building slots.

Queue mechanics

Only 15 civilian factories can work a single construction line at once. Queue more than that on one building and the extras sit idle. Spread your queue across a few projects instead, or let short lines finish while a long one soaks the cap.

Fill states one at a time rather than spreading factories evenly. Concentrating in your highest-infrastructure states means every subsequent building goes up faster, and the wiki explicitly recommends stacking industry in central high-infrastructure regions. The counterpoint is that a bombed-out cluster hurts more than spread-out industry, so if you're expecting strategic bombing, maybe don't put literally everything in Berlin.

Consumer goods civs come off the top before anything else sees use, and the count is based on your total factories including ones you gained through trade. As your empire grows, that tax grows with it, which is part of why pushing your economy law down toward War Economy feels so good mid-game.

Conversions and repairs

You can convert civilian factories to military ones at a base cost of 4000, way under the 7200 to build new. The reverse costs 9000, which is rarely worth it. Economy laws discount conversions as they climb, down to -30% at Total Mobilization. If you built too many civs and the war starts tomorrow, converting a stack of them is the fastest fix in the game.

Damaged buildings repair at 1% a day even with zero factories assigned, and assigned factories get a +200% speed bonus on repairs. Repair does steal civs from new construction though, so in a bombing war you're constantly choosing between fixing and growing.

Last thing. Once a state hits 5/5 infrastructure, there's a decision called Region-wide Industrial Integration that adds a building slot for 100 political power. Once per state. On a packed megalopolis region like Greater London, that's one of the better 100 PP spends you'll ever make.

The whole thing is a rhythm. Civs while it's cheap, infrastructure where it pays for itself, military factories when the target date gets close, and a production screen where your rifle lines sit safely above whatever's eating the steel penalty this month. Hit the September 1937 style switch date for your own war date and you'll walk into it with more equipment than the country next door.