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V1, Vr and V2 Takeoff Speed Calculator

V1, Vr and V2 in knots from weight, wing area, thrust, flaps, runway, altitude and temperature, with the balanced field length. Not for flight use. How it works

Use the V1, Vr and V2 Takeoff Speed Calculator

Fills weight, wing area, thrust and engines with approximate figures for the class. The fields stay editable.

Leave empty to derive density altitude from pressure altitude and temperature. When entered, the density model uses your value.

V1 decision speed
132 knots
Vr rotation 143 knots · V2 safety 146 knots
Important aviation limitation: This generic model is for education only. It is not an operating limitation or dispatch value. Use the aircraft-specific AFM/POH, approved performance charts, current runway data, and a qualified pilot or performance engineer before flight.
V1 range that fits
100 to 143 kt
Accelerate-stop at V1
5,412 ft
Accelerate-go at V1
5,412 ft
Balanced field length
5,412 ft
All-engine takeoff distance
4,902 ft
Required field length
5,412 ft
Engine-out climb gradient
4.4 %
Stall speed VSR
130 kt

Scenario context

Runway
7,000 ft · dry
Pressure altitude
0 ft
Temperature
15°C
Density altitude
From pressure altitude and temperature
Weight / flaps
150,000 lb · TO
Wing / thrust
1,320 ft² · 54,000 lbf total · 2 engines

About the V1, Vr and V2 Takeoff Speed Calculator

V1 is the takeoff decision speed: if an engine fails below it the crew stops, at or above it they continue. Vr is the speed to start the rotation and V2 the speed to hold in the climb with one engine out. For an A320-class aircraft at 150,000 lb with flaps TO, on a 7,000 ft dry runway at sea level and 15 °C, the calculator gives V1 132, Vr 143 and V2 146 kt and a balanced field length of 5,412 ft. The speeds are indicated airspeeds from a generic model, not values from any aircraft’s flight manual.

V1, Vr and V2 for each aircraft class preset

Aircraft classWeight (lb)V1 (kt)Vr (kt)V2 (kt)Required field (ft)
Light business jet (Citation CJ3 class)13,8708892942,352
Business jet (Citation X class)36,1001051111143,416
Regional jet (CRJ900 class)84,5001361411456,141
Narrow-body (A320 class)150,0001321431465,412
Narrow-body (737-800 class)155,0001341441485,613
Wide-body (777-300ER class)660,0001481601646,813
Four-engine (747-400 class)870,0001481661708,280

Sea level, 15 °C, flaps TO, dry 10,000 ft runway, no wind. Generic model with rounded public figures, not flight manual values. For the 747-400 class the all-engine distance with its 15% margin (8,280 ft) is longer than the balanced field (7,917 ft), so it sets the required field.

Supported inputs

  • Aircraft class presets: Citation CJ3, Citation X, CRJ900, A320, 737-800, 777-300ER and 747-400
  • Weight 1,000–1,500,000 lb, wing area 100–10,000 ft², total static thrust 500–500,000 lbf (less than twice the weight), 2, 3 or 4 engines
  • Runway length 1,000–20,000 ft on a dry, wet or icy surface
  • Pressure altitude −1,000–45,000 ft, temperature −60–60 °C (−76–140 °F), optional density altitude −1,000–50,000 ft
  • Flaps UP, 10, TO, 20, 30 or 40

Supported outputs

  • V1, Vr, V2 and the stall reference speed VSR in knots indicated airspeed
  • The lowest and highest V1 that fit the runway
  • Accelerate-stop and accelerate-go distances, balanced field length, all-engine takeoff distance with its 15% margin and the required field length, in feet
  • Engine-out climb gradient in percent, with a warning below the 14 CFR 25.121 minimum for the engine count

Methodology

VSR = √(2W ÷ (ρ0 × S × CLmax)) with sea-level density, so the V-speeds are indicated airspeeds; CLmax runs from 1.5 clean to 2.5 at flaps 40. Vr = 1.10 × VSR and V2 = 1.13 × VSR. Distances use true airspeed and mean accelerations from 80% of the density-lapsed thrust less 2% rolling friction. V1 is the speed at which accelerate-stop equals accelerate-go, kept inside the range for which both fit the runway.

Assumptions

  • Lift coefficients, the thrust lapse (σ^0.7), 80% mean thrust, braking of 12, 8 and 4 ft/s², 2 s to react at V1, 3 s of rotation and L/D 10 (8 with flaps 30 and 40) are typical values, not data for any type.
  • Level runway, no wind or slope, no contamination depth, and no brake-energy or tyre-speed limits. V1 is never set below 0.7 × Vr, which stands in for the minimum control speed on the ground.
  • Preset weights are example takeoff weights below each class’s maximum; wing areas and thrust are rounded public figures.
  • A density altitude you type replaces the temperature in the density model.

How to use this tool

  1. Pick an aircraft class preset, or type the weight, wing area, total static thrust and number of engines yourself.
  2. Set the flaps, runway length and surface, pressure altitude and temperature (the °C button switches to °F). A density altitude typed in replaces the temperature.
  3. Read V1, Vr and V2 in knots, the range of V1 speeds the runway allows and the field lengths. A message takes the place of V1 when the runway is too short or the aircraft cannot climb on the remaining engines.

Frequently asked questions

What is V1 speed?
The federal definition in 14 CFR 1.2 has two halves: the maximum speed at which the pilot must take the first action to stop within the accelerate-stop distance, and the minimum speed at which, after an engine failure, the takeoff can continue to the required height within the takeoff distance. Below V1 you stop; at or above it you go.
Why does V1 change on a wet runway when Vr does not?
Vr and V2 come from the stall speed, which depends on weight, wing and flaps, not on the runway. Braking only matters for the stop, so weaker braking pulls V1 down: the A320-class default goes from V1 132 kt dry to 125 kt wet and 109 kt on ice, while Vr stays at 143 kt and V2 at 146 kt.
Why don’t Vr and V2 rise at a hot, high airport?
They are indicated airspeeds, and the wing needs the same indicated airspeed to lift the same weight in thin air. What grows is the ground speed and so the distance: at 8,000 ft and 35 °C the A320-class default keeps Vr 143 and V2 146 kt, but the balanced field length goes from 5,412 to 10,329 ft and the engine-out climb gradient drops from 4.4% to 1.2%, under the 2.4% a twin must hold, so a real flight would have to take off lighter.
How do flaps change the speeds?
More flap raises the wing’s maximum lift, which lowers every speed. For the A320-class default Vr is 146 kt with flaps 10, 143 kt with TO and 139 kt with 20. Taking off clean (UP) needs Vr 165 kt and a balanced field of 6,945 ft instead of 5,412 ft.
Are these the real A320 or 737 V-speeds?
No. Real V-speeds come from the manufacturer’s performance data for the exact weight, centre of gravity, thrust rating, flap setting, runway, wind and conditions, usually through the FMS or an EFB performance tool. The presets use rounded public figures in a generic model, so they show how the numbers move, not what a given airframe will use.
Can I use this for a real flight?
No. Takeoff speeds for a flight come from the aircraft flight manual or POH, approved performance charts and current runway data.

Speeds for an A320, a 737 or a business jet

Pick an aircraft class to fill the weight, wing area, thrust and engine count, or type your own. With the A320-class defaults (150,000 lb, 1,320 ft² wing, two 27,000 lbf engines, flaps TO, a 7,000 ft dry runway at sea level and 15 °C) the tool gives V1 132, Vr 143 and V2 146 kt and a balanced field length of 5,412 ft. Each input moves the answer the way it moves it on a real aircraft. At 170,000 lb Vr rises to 152 kt and the field length to 6,902 ft. Flaps 20 lowers Vr to 139 kt. A wet runway lowers V1 to 125 kt and an icy one to 109 kt, because weaker braking means a rejected takeoff has to start sooner. Hot and high (8,000 ft at 35 °C) leaves Vr and V2 where they were, because they are indicated airspeeds, but the field length grows to 10,329 ft and the engine-out climb gradient falls to 1.2%, below the 2.4% a twin has to hold. The figures come from a generic model, not from any aircraft’s flight manual: use them to learn and to sanity-check simulator numbers, never to fly.

How the model finds V1, Vr and V2

Stall speed comes from the lift equation VSR = √(2W ÷ (ρ0 × S × CLmax)) with sea-level density ρ0, so the speeds are indicated airspeeds. CLmax depends on the flaps: 1.5 clean, 1.9 at 10, 2.0 at TO, 2.1 at 20, 2.3 at 30 and 2.5 at 40. Then V2 = 1.13 × VSR, the minimum in 14 CFR 25.107, and Vr = 1.10 × VSR. Distances use true airspeed. Thrust falls with air density as T0 × σ^0.7, the ground roll averages 80% of it, and rolling friction takes 2% of the weight. Accelerate-stop is the all-engine run to V1, 2 seconds at V1 to react, then braking at 12, 8 or 4 ft/s² on a dry, wet or icy runway. Accelerate-go is the same run to V1, one engine out from V1 to Vr, 3 seconds of rotation at Vr, then the climb to 35 ft at the engine-out gradient: 80% of the remaining thrust over the weight, less 1 ÷ L/D (L/D 10, or 8 with flaps 30 and 40). V1 is the speed where the two distances are equal, the balanced field length, held inside the range of speeds for which both fit the runway and never below 0.7 × Vr. The all-engine distance to 35 ft plus 15% (14 CFR 25.113) has to fit as well. No V1 is shown when the runway is too short or the remaining engines cannot hold a climb.

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