Thrust-to-Weight Calculator
Check the thrust-to-weight ratio of a build from motor thrust and all-up weight.
How this calculator works
TWR = (max thrust per motor × motor count) ÷ all-up weight
Four motors making 1500 g each on a 650 g quad give 6000 ÷ 650 ≈ 9.2:1. The ratio says how much of your throttle range does real work: at 9:1 a hover sits near 11% throttle, leaving the rest for acceleration.
Where the thrust number comes from
Use bench data, not guesses. Motor pages here carry the manufacturer's own test tables - per KV, per propeller, per throttle step - and this calculator arrives pre-filled with that motor's measured maximum when you open it from a motor page. How to read those tables: motor bench tables explained.
Bench thrust is measured on a stand with a fresh pack; in the air you'll get less. That's fine for comparisons - every motor loses the same way.
What the ratio means in practice
| TWR | What it flies like |
|---|---|
| < 2:1 | Barely climbs; camera platforms only |
| 2-4:1 | Relaxed cruising, long-range efficiency zone |
| 4-8:1 | Freestyle sweet spot - authority without twitchiness |
| 8-12:1 | Racing, aggressive freestyle |
| 12:1+ | Pro racing; most pilots just get worse control |
More is not automatically better: past your skill level, extra thrust mostly amplifies stick errors and drains packs faster.
The lever most people ignore
Weight sits in the denominator, so shedding 50 g moves TWR as much as a motor upgrade. Add up your build honestly with the AUW builder - battery choice alone (how to pick one) swings all-up weight by 20-30%, which is why the same quad feels like two different aircraft on a 1100 and a 1500 mAh pack.