Required Vertical Speed Calculator
Crossing restrictions ask you to be at a particular altitude by the time you reach a fix, and meeting them reliably means knowing the vertical speed required rather than guessing. The logic is simple: the time available is the distance to the fix divided by ground speed, and the required vertical speed is the altitude to change divided by that time. This calculator takes the altitude difference, the distance to the fix, and your ground speed, then returns the time available, the required vertical speed in feet per minute, and whether it is a climb or descent. If the rate exceeds your aircraft's capability, start earlier or slow down.
Required vertical speed formula
Altitude to change = |current altitude - restriction altitude|
Time to fix (min) = (distance / ground speed) * 60
Required vertical speed = altitude to change / time to fix
Equivalently = altitude to change * ground speed / (distance * 60)
Distance is in nautical miles and ground speed in knots, so distance over ground speed is in hours; multiplying by 60 gives minutes. The direction is a descent when the restriction is below your current altitude.
Crossing restriction notes
- A faster ground speed shortens the time available and raises the required vertical speed.
- Compare the required rate to your aircraft's sustainable climb or descent rate before relying on it.
- If the rate is too high, begin the altitude change earlier or reduce speed where allowed.
- Recompute when wind shifts, since ground speed drives the time available.
- Build in a small buffer so you reach the altitude slightly before the fix, not exactly at it.
Required vertical speed: frequently asked questions
How do I calculate the vertical speed needed to make a crossing restriction?
Divide the distance to the fix by ground speed to get the time available in minutes, then divide the altitude you must climb or descend by that time. The result is the vertical speed in feet per minute. The calculator does this as altitude times ground speed, divided by distance times 60.
What is a crossing restriction?
A crossing restriction is an instruction to cross a named fix at, at or above, or at or below a specified altitude. Meeting it requires planning a climb or descent so the altitude change is complete by the time you reach the fix, which is exactly what this required vertical speed tells you.
Does it matter whether I am climbing or descending?
The magnitude of the required vertical speed is the same either way; only the sign changes. Enter the altitude difference between your current altitude and the restriction altitude. The calculator reports the rate needed and whether it is a climb or a descent based on the sign of that difference.
How does ground speed affect the required rate?
A higher ground speed means you reach the fix sooner, leaving less time to make the altitude change, so the required vertical speed is greater. If the wind or your speed changes, recompute, because a faster ground speed can push the required rate beyond what the aircraft can sustain.
What if the required rate exceeds the aircraft's capability?
If the computed rate is more than the aircraft can climb or descend at, you cannot meet the restriction from your current position and speed. In that case begin the altitude change earlier, reduce speed where permitted, or advise air traffic control that you are unable to comply.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.