Research

Research is used to unlock technologies.

Research slots

Technology is unlocked by assigning a research slot to it for the required number of days.

The base number of research slots depends on the country:

• USA, democratic Germany: 4 slots, plus 2 additional possible via national focus. (Democratic Germany requires Waking the Tiger).
• Non-democratic Germany, Italy, Japan, United Kingdom: 4 slots, plus 1 additional possible via national focus.
• France, Soviet Union, most other countries in Europe, plus Canada: 3 slots, plus 2 additional possible via national focus (in Canada's case, the last 1 requires independence).
• Other countries outside of Europe as well as Luxembourg, Bulgaria and Albania: 2 slots, plus 3 additional possible via national focus (for British subjects, the final 2 also require independence).
• New Zealand: 2 slots, plus 4 additional possible via national focus. (Requires Together for Victory).

For most countries, unlocking the final research slot requires having a substantial number of factories (usually 50+). The Commonwealth countries must (with Together for Victory) additionally become fully independent to maximize their available research slots.

Each research slot can store 30 days of research while unused.

Research time

Each technology has a base time cost:

Cost (days)	Techs
42	Armor Submodels
85	Artillery (II) & Upgrades (II,III,IV); Anti-Air Artillery (II,III) & Upgrades; Rocket Artillery (II) & Upgrades; Anti-Tank Artillery (II,III) & Upgrades Support Equipment; Carrier Airplanes; Electronic Mechanical Engineering; Encryption
127	Infantry Weapons (I) & Upgrades (I,III); Support & Anti-Tank Weapons; Motorized Rocket Artillery; Marines (II), Mountain Infantry (II), Paratroopers (II) Support Companies (II,III,IV); Artillery (I) & Upgrades (I); Anti-Air Artillery (I); Anti-Tank Artillery (I) Shiphulls (I); Transports (I); 1st Land Doctrine; 1st Air Doctrine Radio; Radio Detection; Decimetric Radar (I); Decryption; Experimental Rockets; Rocket Engines (II,III) Machine Tools (I,II); Equipment Conversion; Oil Processing; Rubber Processing
170	Infantry Weapons (II,III) & Upgrade (II); Night Vision (II); Motorized & Mechanized (I,II); Marines (I,III), Mountain Infantry (I,III), Paratroopers (I,III); Special Forces Programs Support Companies (I); Artillery (III); Rocket Artillery (I); Great War Tank, Light, Medium & Heavy (I) Armor Shiphulls (II,III,IV); Transports (II,III); Naval Doctrines Airplanes Decimetric Radar(II); Rocket Engines(I); Jet Engines Machine Tools(III); Production Line (I); Industry; Construction; Excavation
212	Night Vision (I); Modern, Super Heavy & Heavy (II,III) Armor; Centimetric Radar; Computing; Production Line (II)
255	Mechanized (III); Air doctrines (not 1st); Naval doctrines; Fuel Refining
382	Land doctrines (not 1st)
425	Nuclear technology

Research speed

The base research cost only represents an abstract number of days the research will take. In practice, due to modifiers, research will progress by more or less than exactly one research-cost-day per day. All modifiers stack additively.

The research speed is calculated every day for each slot, so changes in research speed (except limited-use bonuses) apply to all ongoing research as well. The research speed can not fall below 10% of the default speed.

Research modifiers

Difficulty

The player can get a research speed bonus or penalty depending on the game difficulty setting as follows:

• Civilian +15% bonus
• Recruit +7% bonus
• Regular no bonus or penalty
• Veteran -15% penalty
• Elite -30% penalty

Trade law

Main article: Ideas#Trade_laws

Trade laws can also increase research speed. The more open the trade the higher the reduction as can be seen below.

Law	Resources to Market	Dockyard/ Factory Output	Construction Speed	Research Speed	Prerequisites
Free Trade	80%	+15%	+15%	+10%	–
Export Focus	50%	+10%	+10%	+5%	–
Limited Exports	25%	+5%	+5%	+1%	One of the following must be true: All of the following must be true: At war. Current ruling party is Democratic. Any enemy country has more than 20% of this country's total number of factories. All of the following must be true: Current ruling party is not Democratic. has economy law: Partial Mobilization, War Economy or Total Mobilization.
Closed Economy	0%	–	–	–	At war Current ruling party is Fascist or Communist. has economy law: War Economy or Total Mobilization. If this country is the Soviet Union, it should not have the ‘Molotov-Ribbentrop Pact’.

Technologies that increase research speed

Technology	Year	Research Speed
Electronic Mechanical Engineering	1936	+3%
Mechanical Computing	1936	+4%
Computing Machine	1938	+5%
Improved Computing Machine	1940	+8%
Atomic Research	1940	+4%
Advanced Computing Machine	1942	+8%

Limited-use bonuses

Available limited-use research bonus automatically get activated when an applicable technology gets selected for research. The bonus is then tied to this technology and research slot. A research bonus can alternatively or simultaneously be an ahead-of-time bonus, which reduces the time span until the tech becomes current by the stated amount. This reduces the ahead-of-time penalty (see below).

Unlimited bonuses

Various national ideas, like designers, theorist, and concerns continuously improve the research speed for applicable technologies while they are active. Design companies can additionally improve equipment being unlocked while they are active.

Equipment licensing

When licensing equipment from another country, researching that equipment gets a speed bonus of +20%.

Technology sharing

When a country is part of a research group, it gets a research speed bonus for each other country in the group that has already unlocked that technology, up to +50%. Subjects benefit less from technology sharing, depending on their autonomy level.

Ahead-of-time penalty

Most technologies (except doctrines) have a date attached to them when they become current. Researching them earlier comes at the cost of reduced research speed. Each year ahead adds +200% to the ahead-of-time (AOT) penalty, which divides the research speed. For example 365 days before a technology becomes current, research speed gets divided by 3; 730 days ahead, it is divided by 5 etc. As the research speed is re-calculated every day, the speed penalty slowly goes down even while a technology is being researched.

Ignoring other speed modifiers a technology starting to research X years before the date it becomes current, with a base research cost of N days will take ${\frac {1}{2}}(-e^{-2*{\frac {N}{365}}}(2x+1)+2x+1){\text{ years}}$. This assumes the research starts with a speed higher than the minimum and finishes before the technology becomes current. Other speed modifiers change this duration linearly.

Technologies

Technologies allow countries to unlock production of new units such as mechanized infantry, paratroopers, tanks and all kinds of airplanes; new equipment, from infantry weapons to carrier air groups and specialized armored units; as well as defensive and productive structures.

On the other hand, most technologies serve to improve the efficiency of current units. This can be achieved through a number of ways, such as improving the damage inflicted by the unit, its ability to penetrate the armor of armored units, its defensiveness and organization or simply its ability to detect enemy units.

It is possible to research improvements of already researched technologies. There could be small buttons on technology (e.g. possibility to operate from carriers for airframe). These improvements have to be researched separately.

Land

• Infantry technology: Technologies that improve infantry weapons and equipment, unlock or improve motorized and mechanized units as well as special forces (marines, mountaineers and paratroopers).
• Artillery technology: Technologies that unlock and improve all types of artillery, including anti-tank, anti-air and rocket artillery.
• Support Companies technology: Technologies that unlock and improve all types of support battalions: Engineers, Reconnaissance, Military Police, Maintenance, Field Hospital, Logistics and Signal companies.
• Armor technology: Technologies that unlock all types and models of tanks, from light to super heavy chassis, as well as their variants: tank destroyer, self-propelled artillery and self-propelled anti-air.
• Land doctrine: Unlocks one of the four land doctrine trees: mobile warfare, superior firepower, grand battleplan and mass assault.

Naval

• Naval technology: Technologies that unlocks or improve all kinds of ship units: destroyer, cruisers, battleship, carrier, submarine or improve transports for naval invasions.
• Naval doctrine: Unlocks one of the three naval doctrine trees: fleet in being, trade interdiction and base strike.

Air

• Air technology: Technologies that unlock or improve all types of airframes: light, medium or heavy, as well as their jet propulsion versions.
• Air doctrine: Unlocks one of the three air doctrine trees: strategic destruction, battlefield support and operational integrity.

Industry

• Engineering technology: Groups all technologies related to electronic engineering (computers, radios, cryptography), rockets and atomic research.
• Industry technology: Groups all technologies that improve production efficiency and volume of all factories, resources excavation and unlocks synthetic refineries.

Doctrines

All doctrines listed above serve to improve units in a specific role by providing them one or multiple bonuses once the doctrine has been researched. Some of these bonuses can be obtained through more than one doctrine, but at different depth of the doctrine tree and most bonuses are unique to a specific doctrine.

It's also necessary for all players to make a choice when researching doctrines, as opposed to all other technologies (with the exception of Industry) that can be entirely researched. Only one doctrine can be researched out of three or four options, depending on the doctrine type (land, naval or air).

It's possible to change doctrine throughout the game, but all bonuses from the old doctrine are lost, as if completely abandoned, when starting research of a different doctrine tree. There are no ahead of time penalties of doctrines.