What it's for: a single read on how consistently the world's rockets fly near-full — each launch scored against that same rocket's own proven best flight to low orbit, then averaged across the fleet.
For each rocket family, every LEO flight's payload mass is compared to that family's own demonstrated best — the 95th-percentile payload it has carried to low orbit over the last 24months. “Utilization” is how close a flight came to that self-set ceiling.
This is a consistency measure, not a cross-rocket efficiency ranking. Each family is scored against its own ceiling, so a higher % means a family flies near-full more reliably — not that it is “better” than a family with a lower one. Comparing a rocket to its published max-to-LEO capacity instead would unfairly punish vehicles that fly higher or more-inclined orbits.
Mean fill — all flights vs commercial-only — sorted by all-flights utilization. Peak is the 95th-percentile payload each family has flown to LEO.
34 more families flew LEO launches in the window but fewer than 5 — too few to rank reliably.
Every scored flight is plotted as a single dot, by how full it flew. Tighter clusters near the right mean more consistent loading; the vertical mark is the family's mean.
For each rocket family, how close its LEO flights come to that family’s own demonstrated best payload — a measure of how consistently it flies near-full, not a cross-rocket efficiency ranking.
Jonathan McDowell’s GCAT. Payload mass and launch vehicle from launch.tsv; each launch’s orbit is classified by joining to its catalogued payloads in satcat.tsv via Launch_Tag and reading OpOrbit.
For each LEO launch, fill = payload mass ÷ the family’s peak. A family’s score is the mean fill across its launches in the trailing 12 months; the global figure is the mean across every scored launch.
A family’s “demonstrated best” is the 95th-percentile payload mass it has carried to LEO over the trailing 24 months — not the single heaviest flight (one freak overloaded launch could set an unreachable ceiling) and not an all-time figure (which would hold a retired vehicle’s record against current flights).
Comparing actual mass to a rocket’s published maximum-to-LEO capacity would punish vehicles that fly high-inclination or high-altitude orbits, because published capacity is quoted to a low reference orbit. Scoring each family against its own demonstrated ceiling removes that orbit-mix bias.
Each family is measured against its own ceiling, so the leaderboard is a consistency measure — how reliably a family flies near-full — not a claim that one rocket is more efficient than another. A higher % is not “better”; it means a family’s flights cluster more tightly near its own demonstrated best.
I show two figures. “Commercial-only” excludes internal logistics — launches where the launch provider also operates the payload. In v1 this is a curated rule covering the only material case, SpaceX flying Starlink. The split matters: Starlink flights fly near-full by design and dominate launch volume, so the all-launches figure would otherwise mostly describe Starlink.
Successful orbital launches (GCAT LaunchCode = OS) classified as LEO, in the trailing 12 months, for families with at least 5 such launches.
Non-LEO launches (GTO, MEO, GEO, deep-space), families below the 5-launch threshold, and very recent launches whose payloads are not yet catalogued with an orbit.
GCAT records small payload masses coarsely (rounded to roughly 100 kg), so small-launcher peaks may read low and their fill rates correspondingly high — Electron is the main case. The rolling 24-month peak moves over time, so a family’s % is not directly comparable year-over-year. The internal/commercial split is a curated v1 approximation, not a general operator-vs-provider computation.
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