Flight numbers explained

Speed

Speed is the rim speed the disc is designed for, on the maker's own 1–14 scale. It is not a measurement in metres per second. A high-speed driver has a wide, sharp rim; a putter has a deep, blunt one. The number tells you how hard the disc wants to be thrown, and therefore who it is for.

A disc thrown below its speed flies slower than its rating suggests: it fades early and does not carry. A disc thrown above its speed can turn further than intended. That is why a beginner often gets more distance from a midrange than from a distance driver, even though the driver has the higher number.

Glide

Glide is how well the disc stays in the air, from 1 to 7. High glide keeps the disc aloft longer and makes it more sensitive to wind and to a high or low release. Low glide is easier to control into wind and on a low line. Glide is the number people notice last and the one that changes a disc's character most.

Turn

Turn describes how much the disc curves right at the start of its flight for a right-hand backhand, before it fades back. It is written from +1 (very resistant to turning) to −5 or lower (very willing). A negative turn is not a bad thing: it is what lets a slower arm get a full flight out of a disc, and what lets a faster arm shape a turnover.

Turn is the number most dependent on arm speed. A disc with −3 turn thrown by a strong arm may flip over; thrown by a slower arm it may fly straight. The number is the disc's potential, not its behaviour in your hand.

Fade

Fade is how strongly the disc hooks left at the end of a right-hand backhand, from 0 to 5. It is the low-speed part of the flight, so it shows up late and is less affected by arm speed than turn. A fade of 4 or 5 finishes hard; a fade of 0 lands almost where it was pointing.

How the four work together

A disc with high speed, low turn and high fade is a wind-fighting driver: it will not flip, and it finishes left. A disc with high glide, negative turn and low fade is a turnover midrange: it drifts right and stays there. A putter with low speed, low glide and moderate fade is a straight, predictable approach disc.

The useful comparison is not the sum of the numbers but the shape of the flight. The chart above draws that shape for one disc. Change the disc in the flight chart or add several to compare them at the same arm speed.

A worked example

Take a Destroyer: 12 speed, 5 glide, −1 turn, 3 fade. At intermediate arm speed it drifts right through the middle of the flight, then fades back across the centre line and lands about 14 m left at 128 m. At pro arm speed the extra speed makes the turn stronger and the fade weaker, so it lands closer to straight at 168 m. The numbers did not change; the arm did.

That is the point of a flight chart. It does not tell you a disc is good or bad. It shows what the disc does at the speed you actually throw, which is the only question that matters when you are choosing one.

Where the numbers come from

Every manufacturer publishes its own ratings. Innova's scale is the one most people learn first; Discraft, Discmania, Latitude 64 and the rest use their own. The catalogue on this site records each maker's published numbers with a source, and says plainly that they are ratings rather than measurements.