Kerbal Space Program puts you in charge of a fledgling space agency on the planet Kerbin, where you design, build, and fly rockets using realistic orbital mechanics. The game uses a simplified but accurate Newtonian physics model — you need to understand delta-v budgets, transfer orbits, and staging to reach other planets. With Career, Science, and Sandbox modes, KSP caters to both structured progression and creative engineering. The modding community adds thousands of parts, visual overhauls, and automation tools that extend the game indefinitely.
Your choice of equipment defines your damage output and playstyle. This guide ranks every major option, explains what makes each one strong, and tells you which builds they pair best with.
Equipment Rankings
| Equipment | Tier | Best For | Notes |
|---|---|---|---|
| SRB Booster | S | First-stage boosters on all early career rockets | Solid Rocket Boosters provide massive thrust at low cost but cannot be throttled or shut down once ignited. |
| Mainsail Engine | A | Main stage engine for medium-to-heavy launch vehicles | The RE-M3 Mainsail is KSP's workhorse heavy lifter engine with 1,500 kN thrust and 310s vacuum Isp. |
| Nuclear Engine | A | Interplanetary transfer stages for Duna, Jool, and beyond | The LV-N Nerv nuclear engine has only 60 kN of thrust but an exceptional 800s vacuum Isp, making it the most fuel-efficient engine for interplanetary transfers. |
| Ion Engine | B | Lightweight deep-space probes and satellite repositioning | The IX-6315 Dawn ion engine provides incredible 4,200s Isp but only 2 kN of thrust, requiring enormous electricity reserves (xenon gas + solar panels or RTGs). |
| SAS Module | B | All crewed and uncrewed vessels for attitude control | The Advanced Inline Stabilizer provides torque to rotate your craft without using RCS fuel. |
S-Tier: SRB Booster
Solid Rocket Boosters provide massive thrust at low cost but cannot be throttled or shut down once ignited. The Kickback SRB delivers 2,300 kN of thrust, making it ideal for first-stage boosters. Pair 2-4 SRBs with a liquid-fuel core stage for cheap, powerful launchers.
| Attribute | Detail |
|---|---|
| Tier | S |
| Best For | First-stage boosters on all early career rockets |
| Key Mechanic | orbital mechanics |
| Recommended Build | Pilot |
How to get it: Available from mid-game onward. See our walkthrough for the exact progression point.
Best builds using SRB Booster: Pairs naturally with Pilot thanks to stat scaling synergies.
A-Tier: Mainsail Engine
The RE-M3 Mainsail is KSP's workhorse heavy lifter engine with 1,500 kN thrust and 310s vacuum Isp. It's the go-to engine for large rockets' first and second stages. While heavy at 6 tons, its thrust-to-weight ratio makes it essential for getting heavy payloads to orbit.
| Attribute | Detail |
|---|---|
| Tier | A |
| Best For | Main stage engine for medium-to-heavy launch vehicles |
| Key Mechanic | staging |
| Recommended Build | Engineer |
How to get it: Accessible in the early-to-mid game. Check our maps guide for the location.
Best builds using Mainsail Engine: Pairs naturally with Engineer thanks to stat scaling synergies.
A-Tier: Nuclear Engine
The LV-N Nerv nuclear engine has only 60 kN of thrust but an exceptional 800s vacuum Isp, making it the most fuel-efficient engine for interplanetary transfers. It's heavy (3 tons) and weak in atmosphere, so use it only on upper stages. Multiple Nervs in parallel solve the low-thrust problem.
| Attribute | Detail |
|---|---|
| Tier | A |
| Best For | Interplanetary transfer stages for Duna, Jool, and beyond |
| Key Mechanic | delta-v budgets |
| Recommended Build | Scientist |
How to get it: Accessible in the early-to-mid game. Check our maps guide for the location.
Best builds using Nuclear Engine: Pairs naturally with Scientist thanks to stat scaling synergies.
B-Tier: Ion Engine
The IX-6315 Dawn ion engine provides incredible 4,200s Isp but only 2 kN of thrust, requiring enormous electricity reserves (xenon gas + solar panels or RTGs). Ion drives are for lightweight probes on deep-space missions where burn time doesn't matter.
| Attribute | Detail |
|---|---|
| Tier | B |
| Best For | Lightweight deep-space probes and satellite repositioning |
| Key Mechanic | docking |
| Recommended Build | Tourist |
How to get it: Found in later areas. Our walkthrough covers when you can access this.
Best builds using Ion Engine: Pairs naturally with Tourist thanks to stat scaling synergies.
B-Tier: SAS Module
The Advanced Inline Stabilizer provides torque to rotate your craft without using RCS fuel. Larger craft need multiple SAS modules or reaction wheels to maintain stability during burns. SAS works with pilot skill levels to enable heading holds.
| Attribute | Detail |
|---|---|
| Tier | B |
| Best For | All crewed and uncrewed vessels for attitude control |
| Key Mechanic | science collection |
| Recommended Build | Rescue Target |
How to get it: Found in later areas. Our walkthrough covers when you can access this.
Best builds using SAS Module: Pairs naturally with Rescue Target thanks to stat scaling synergies.
Equipment Progression Path
The order you should acquire equipment as you progress:
- Starting gear → Enough to clear Kerbin
- Mainsail Engine → Your first real upgrade, available early
- Nuclear Engine → Mid-game upgrade with good scaling
- SRB Booster → Best-in-slot, aim for this by late game
- Upgrade to max → The power spike from max upgrades is enormous
Equipment Tips
- Always upgrade your primary equipment before diversifying — one strong option beats three mediocre ones.
- Match your equipment to your build's stat priorities for maximum scaling.
- Achieve stable Kerbin orbit (both apoapsis and periapsis above 70km) before attempting the Mun — if you can orbit, you understand 80% of what you need for the whole game.
- Check our tier list for how equipment rankings affect overall build effectiveness.
More Kerbal Space Program Guides
- Kerbal Space Program Kerbal Space Program Overview
- Kerbal Space Program Best Builds
- Kerbal Space Program Tier List
- Kerbal Space Program Walkthrough
- Kerbal Space Program Beginner's Guide
- Kerbal Space Program Tips & Tricks
- Kerbal Space Program Combat Guide
- Kerbal Space Program Boss Guide
- Kerbal Space Program Maps & Locations
- Kerbal Space Program Crafting Guide
- Kerbal Space Program Classes & Characters
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- Satisfactory Weapons Guide — simulation game with similar mechanics
- The Sims 4 Weapons Guide — simulation game with similar mechanics
