Raptor 4: "300 tons of thrust, about the same mass." Reading Musk's new target against SpaceX's official Raptor 3 numbers

In a post on X on October 26, 2026 (UTC), Elon Musk wrote that "Raptor 4 will be 300 tons of thrust at sea level and hopefully about the same mass." The Raptor 3 sea-level engine that SpaceX described on August 3, 2024 has 280 tf of thrust, a specific impulse of 350 s and an engine mass of 1,525 kg. 300 tons is about 7% more than Raptor 3, and at the same mass the thrust-to-weight ratio would rise from about 184 to about 197. This is a development target, not an official specification.

3-line summary

• On October 26, 2026 (UTC), Elon Musk wrote on X that SpaceX's next engine, Raptor 4, "will be 300 tons of thrust at sea level", "hopefully about the same mass."
• According to SpaceX, today's Raptor 3 (sea-level version) has 280 tf of thrust and a mass of 1,525 kg. 300 tons is an increase of about 7%, and if the mass stays the same, every kilogram of engine pushes harder.
• Applied to Super Heavy's 33 engines, total thrust would rise on paper from about 9,240 tons to about 9,900 tons. This is a target; no official specification or schedule has been announced.

Background: thrust, "tons" of thrust, thrust-to-weight ratio, specific impulse

Thrust is the force with which an engine pushes the vehicle. A rocket burns propellant and blasts the hot gas out of its nozzle at tremendous speed. Pushing gas backward pushes the engine forward, just as a balloon flies away from the direction its air rushes out. This reaction force is thrust, usually measured in newtons (N) or kilonewtons (kN). To leave the ground, a rocket's thrust must be greater than its total weight.

"300 tons of thrust" means "a force able to lift 300 tons." SpaceX sometimes writes thrust in tonnes-force (tf). One tf equals the gravitational force on one metric ton at Earth's surface, about 9.8 kN, so 300 tf is about 2,940 kN. The confusing part is that "300 tons" describes the force the engine produces, not the engine's weight. It is like saying a 60 kg person can lift a 300 kg barbell. For comparison, Falcon 9's Merlin engine produces 845 kN (SpaceX), or about 86 tf. Raptor 3 is more than three times that.

Thrust-to-weight ratio tells you how many times its own weight an engine can push. Divide thrust by engine mass: the bigger the number, the lighter and stronger the engine. For Raptor 3, 280 tons-force ÷ 1.525 tons ≈ 184. On a vehicle with 33 engines like Super Heavy, a difference of just 100 kg per engine adds up to 3.3 tons. That is why "more thrust at the same mass" matters so much.

Specific impulse is the rocket's "fuel economy." Measured in seconds, it tells you how long a given amount of propellant can keep producing a given thrust. Higher is more efficient. SpaceX lists Raptor 3's sea-level specific impulse as 350 s. Thrust is strength; specific impulse is efficiency. They are different yardsticks, explained with worked examples in our thrust and specific impulse article.

What happened

At 13:58 UTC on October 26, 2026, Musk replied to another user's post about Raptor 3's performance:

Because it is a reply in a thread about Raptor 3, "the same mass" reads as a comparison with Raptor 3.

SpaceX published the Raptor 3 figures on X on August 3, 2024.

What the numbers change (our calculation)

These values are our own calculations from the published figures, assuming Raptor 4 has the same 1,525 kg mass as Raptor 3.

Seven percent sounds small, but it is not. The roughly 660 extra tons-force across 33 engines is more than adding two extra Raptor 3 engines, without adding weight. More engines mean more plumbing, more control and more parts that can fail; a stronger engine avoids that.

A common mistake: the "30% boost" headline. Some reports describe a 30% increase in thrust. Compared with the official Raptor 3 figure of 280 tf, though, 300 tons is about 7% more. Percentages depend entirely on what you compare against. SpaceX's Starship page, for example, lists Raptor thrust as 250 tf (checked October 16, 2026); against that, 300 tons is 20% more. Whenever you see "X% more," first ask "compared with what?"

Why it matters

Rocketry is a fight against mass. Most of a rocket's mass is propellant, and the payload is a small fraction. A lighter engine lets the same thrust carry more payload; more thrust at the same mass lets you lift a heavier vehicle, with more propellant or more cargo.

Starship uses a lot of engines. Super Heavy carries 33 Raptors and the Starship upper stage carries six (three Raptors and three Raptor Vacuum engines), according to SpaceX. Every improvement to one engine is multiplied by 33 or by six.

It also ties into cost goals. In a post on X on November 3, 2025, Musk wrote that Raptor 4 "should beat Merlin by >10X in $/ton of thrust, with further improvement in TWR and ISP." The new "300 tons at about the same mass" puts a concrete number on that thrust-to-weight goal.

How it works: why more force without more mass is possible

Thrust depends on how much propellant you burn and how fast you throw it out. Roughly, thrust is the mass of gas expelled per second times its exhaust speed. Raising combustion chamber pressure lets an engine of the same size burn more propellant and push gas out harder, so thrust can rise without making the engine bigger.

Raptor is designed for high pressure. It is a full-flow staged combustion engine burning methane and liquid oxygen. Partially burned fuel-rich and oxygen-rich gases drive the turbopumps, and all of that gas then goes into the main chamber instead of being dumped. Merlin's gas-generator cycle throws some of that gas away. Wasting nothing allows higher chamber pressure. See our Merlin vs. Raptor comparison.

My own view: the hard part is materials and cooling. Higher pressure means more force and heat on chamber walls and pumps. Making parts thicker to cope adds weight. "More thrust, same mass" is hard precisely because it means breaking the usual trade-off between strength and weight through design.

Timeline

For the test that fired all 33 Super Heavy engines together, see our Starship Flight 15 booster static fire article.

If you explain it to a friend

• "300 tons of thrust" is not the engine's weight; it is a force that could lift 300 tons.
• Versus Raptor 3 (280 tf), it is about 7% more. "30% more" uses a different baseline.
• The key phrase is "same mass": a 1.5-ton engine pushing with about 200 times its own weight.
• It is a development target stated by Musk, not an official specification.

Next question

If engine thrust goes up, how much more payload can a rocket actually carry to space? Answering that needs the most important equation in rocketry: the rocket equation.

Read next

• Thrust and specific impulse
• Merlin vs. Raptor
• What is Starship?

Sources

• Elon Musk on X (October 26, 2026): https://x.com/elonmusk/status/2114718275238277610
• SpaceX on X (Raptor 3 figures, August 3, 2024): https://x.com/SpaceX/status/1819772716339339664
• Elon Musk on X (November 3, 2025): https://x.com/elonmusk/status/1985187793556111427
• SpaceX, "Starship": https://www.spacex.com/vehicles/starship
• SpaceX, "Falcon 9": https://www.spacex.com/vehicles/falcon-9

Verification status

• Raptor 4's "300 tons" and "about the same mass" are a development target confirmed in Musk's post on X, not an official SpaceX specification.
• Thrust-to-weight ratios, the 33-engine totals and percentage changes are our own calculations from published figures.