Effective Cost Concepts

[!IMPORTANT] This article is primarily aimed at players well into or past their first career who have some experience designing launch vehicles and want to know how the costs associated with a launch are calculated. Most of the information presented will not be useful for a first-time player.

Effective Cost Modifiers

Every part has a tag list, which are attributes of the part that make it costlier to integrate. These modifiers are used to compute the Effective Cost of a part, which is the purchase cost multiplied by all cost modifiers.

For example, consider the XLR41:

It costs 330f to purchase, and has two tags, due to being a pump-fed (turbopump) engine with cryogenic propellants. These combine for a total effective cost of 330 * 1.1 * 4 = 1452.

Pump-fed engines (4x) and avionics (3x) have the highest effective-cost multipliers, and are present on most orbital launch vehicles. They are therefore usually the highest cost-contributors for an uncrewed craft.

[!TIP] While pressure-fed engines are generally less performant than pump-fed engines, they are significantly cheaper to integrate (1.75x v. 4x). Solids are even cheaper (1.05x). If you don't need the performance of a pump-fed engine, consider using a pressure-fed engine or solid to save money.

Human-rating a craft adds a 1.25x multiplier to global costs, and capsules are also just expensive to begin with. This usually makes the crew capsule a significant cost-contributor for a crewed craft.

Any part that has a high purchase cost will also contribute that same amount to effective cost. This mainly applies to solar panels and the adjustable heatshield, both of which can be deceptively expensive.

Fuels/resources also have an effective-cost modifier, which is usually insignificant since resources are usually not a significant portion of a rocket's cost. These modifiers are not visible in-game, but can be found in the source code. In addition, some resources are simply more expensive per litre.

Integration Info Window

The Integration Info Window is the primary overview for stats related to your craft. The BP and EC values (explained below) can be shown by opening the debug console (Alt-F12 by default).

Effective cost (EC) is a unitless metric based solely on the parts/resources present on a rocket. It primarily is used to compare two rockets intended to perform similar tasks. A rocket with lower EC is cheaper and faster to integrate, all other variables being equal. The effective cost of a rocket is the sum of the effective costs of all its parts and resources, multiplied by any global cost modifiers (human-rated, nuclear).

[!WARNING] Effective cost is not a fund value, because it ignores factors such as engineer efficiency and speed modifiers. It is only useful as a metric because it ignores these factors, so designs can be compared across different game-states. The actual cost you pay is better represented through the Net Salary and Launch Cost values.

Effective cost translates into Build Points (BP) through a quasi-linear formula. Build Points are the actual resources that engineers produce. 1 engineer produces 0.0025 BP/s = 216 BP/day while active, which is then multiplied by efficiency and other leader effects.

[!NOTE] The EC -> BP curve has a multiplier for cheap crafts (<4200 EC) that reduces their build cost.

The BP of the craft divided by the BP rate produced by the engineers of the LC gives the total Integration Time reported by the window.

[!NOTE] This integration time takes into account global leader effects on integration speed, but does not take into account conditional effects tied to resource amounts (e.g. Nambi Narayanan's +5% to integration speed on rockets with >10kL of LH2), effects that target specific part types (e.g. Douglas Aircraft Company's +300% integration speed to isogrid tanks), or LC efficiency gain. These three factors are the usual cause of any discrepancy between the reported integration time and the actual integration time.

Rollout Time is calculated based on the difference between EC and purchase cost, and takes longer the higher that difference is. Likewise, Launch Cost = Rollout Cost + Reconditioning Cost is calculated based on the same difference.

Rollout Cost is based on a plethora of different factors, including LC mass, whether the LC and/or craft are human-rated or not, as well as the difference between EC and purchase cost (again). Reconditioning Cost is one-fifths of the Rollout Cost. It is frankly easiest to just use the given Launch Cost as a reference.

Cost Breakdown Window [Currently Unreleased]

This window shows the part-by-part breakdown of the total effective cost of your current rocket, as well as the effective cost after conditional integration speed effects are applied. You probably want to check the cost for a tooled rocket, since the effective cost of an untooled rocket is significantly higher.

For each part, it shows the individual effective cost contributed by that part. That includes the cost of any resources present inside the part (though those are usually considered separately).

[!IMPORTANT] The current implementation does not apply global tags to all parts in the part display list, only those that have the global tag. The Gemini L Cabin in the screenshot above is properly receiving the 1.25x global cost multiplier for a human-rated part, but the avionics and engines are not. This is mainly relevant for crewed vehicles, as well as those using nuclear engines.

Cost-Saving Tricks

These are some common optimisations that can reduce the total effective cost for a mission. There are also some common pitfalls that can significantly reduce the EC/ton-to-LEO of a rocket (for generally not much performance gain).

Payloads

• Deep-Space avionics are expensive, and have the 3x tag. If you're just using the Deep-Space avionics for its hibernation and not the ability to control it outside of 71Mm, consider if using Near-Earth and increasing your power-generation ends up cheaper overall.
• RTGs are expensive, and have a 2.5x tag. All orbiters up to (and maybe including) Jupiter can be adequately powered by solar panels. The degradation really doesn't matter that much when you consider that most of your science will be done within 180 days anyway.
• Solar panels, despite being the primary alternative to RTGs, are also expensive, especially at TL0 and TL1. TL2 and TL3 significantly increase the long-term lifespan of solar panels, and the later techlevels make them significantly cheaper.
• Heatshields, especially the later configurations, are very expensive. They're reentry-rated (for a multiplier of 1.5x), which isn't that bad, but they just cost a lot. A 2.5m lunar heatshield can easily cost upwards of several thousand. Consider using one of the discrete-part heatshields, using a lower-tech heatshield, or downsizing your payload.
• Science experiments make up a significant portion of the cost of later rockets. Note that any experiments placed inside avionics will inherit the 3x tag to cost from the avionics; thankfully this has already been accounted for. (Although, this technically does mean that you should avoid placing in-avionics experiments outside of avionics if possible, since the out-of-avionics versions do not have the 3x cost reduction to account for the tag.) There is not much you can do about this, but it is important to be aware that there is a cost to adding experiments that won't ever be run.

Launch Vehicles

• Untooled parts add to the purchase cost by around 1/4 of the tooling cost. That doesn't sound bad until you realise that this increased purchase cost also affects the effective cost, which often has a much higher multiplier when converted to net salary. You will lose (in real salary paid) basically as much as the unlock credit you saved by not tooling, and the breakeven point for tooling is usually around two launches.
• Balloon tanks significantly increase the EC of a rocket due to their 2.5x multiplier. This is in contrast to isogrid's 1.05x multiplier, which drops to 0.26x when you factor in Douglas Aircraft Company's subcontractor effect. The extra payload gained from using balloon tanks is often not enough to offset the significantly increased cost from using them.
• Avionics cores are expensive! Split-avionics (where you have two or more avionics cores on your launch vehicle) can increase your payload, but (especially for larger launch vehicles) are usually not worth the additional expense of integrating two large Near-Earth avionics cores. Using only one avionics core for your entire launch vehicle will often significantly reduce cost while not affecting the total payload to LEO by too much.
• Stage recovery is usually not worth the expense until the mid-to-lategame. The cost of strapping parachutes onto a stage is paid in engineer salary, and the recovery amount usually is unable to offset that. Additionally, money now is usually worth much more than money later in RP-1. If you are able to profitably boost-back to the Launchpad somehow, kudos to you and let the RP-1 server know.
• Solid boosters are king in terms of thrust/cost, even if they have much worse Isp compared to a good turbopump engine. Using a solid first stage or solid boosters instead of liquid boosters can significantly reduce cost, at the expense of decreasing payload ratio.