RC Aircraft Thrust-to-Weight Calculator

Thrust-to-weight ratio (T/W) is total static thrust divided by all-up weight (AUW), both in the same units.

T/W = total static thrust (g) / all-up weight (g)

A wing changes what the number means, and most T/W tables ignore that.

A multirotor is held up by thrust alone. Below 1.0 it physically cannot leave the ground, and below about 1.5 it has nothing left over to correct with, so it wallows and fights you. That is where the “under 1.0 cannot fly” rule comes from.

A fixed-wing plane is held up by its wing. Thrust only has to overcome drag, which is a small fraction of weight. A full-size Cessna sits near 0.25. An airliner is around 0.3. Plenty of RC gliders and scale models fly happily at 0.4 to 0.6 and would be called “underpowered” by a multirotor table. What T/W actually predicts on a plane is climb angle and vertical performance: at 1.0 a plane can hang on the prop and go straight up, which is a 3D trick, not a requirement for flight.

So pick the right column below.

Fixed-wing benchmarks Under 0.35: marginal, needs a long smooth runway or a hand launch into wind 0.35 to 0.5: gliders, powered sailplanes, scale and slow fliers 0.5 to 0.8: trainers, gentle and forgiving, climbs out steadily 0.8 to 1.2: sport, brisk climb and basic aerobatics 1.2 to 1.8: aerobatic, comfortable vertical lines Over 1.8: 3D, hovering, harriers, torque rolls

Multirotor benchmarks Under 1.0: will not lift off 1.0 to 1.5: lifts off but has no control authority left, unstable and unpleasant 1.5 to 2.5: heavy lift and cinema rigs, smooth and deliberate 2.5 to 4: stable camera and video quads 4 to 6: freestyle FPV Over 6: racing

For a first plane, aim somewhere around 0.7 to 0.9. Higher is faster and twitchier, and it punishes mistakes on landing.

All-up weight has to include everything: airframe, motor, ESC, servos, battery, receiver, and any camera gear. Weigh the finished aircraft on a kitchen scale instead of adding up the spec sheet. Motor and battery weights drift more than people expect, and 50 g on a small model is enough to change how it flies.

One more thing worth building in: static bench thrust is the best number your setup will ever produce. Once the aircraft is moving, the propeller is less effective, and by cruise speed you may be 20 to 30% down on the figure you measured standing still.