Pitot Tube Velocity Calculator
By Santaji GadepatilinUpdated October 27, 2026
A Pitot tube measures flow velocity from the difference between total and static pressure. It is used for air ducts, stacks and aircraft, and an averaging Pitot tube extends the idea to pipe flow measurement. This free Pitot tube velocity calculator solves for whichever value you leave blank and shows the formula and steps.
Velocity (m/s) vs Velocity (dynamic) pressure (Pa) — other inputs held at your current values.
How to use the Pitot tube velocity calculator
Enter the dynamic pressure read from the manometer, the fluid density and the pitot coefficient. The velocity appears straight away. You can also work backwards to find the pressure you should expect for a target velocity.
Pitot tube velocity formula
v = C × √(2ΔP ÷ ρ)
Worked example
Air at 20 °C (ρ = 1.2 kg/m³), pitot reading 500 Pa (5 mbar):
v = √(2 × 500 ÷ 1.2) = 28.9 m/s
Air velocity quick table (ρ = 1.2 kg/m³)
| ΔP (Pa) | Velocity (m/s) |
|---|---|
| 10 | 4.1 |
| 50 | 9.1 |
| 100 | 12.9 |
| 250 | 20.4 |
| 500 | 28.9 |
Flow from a single velocity
A pitot tube measures point velocity. To get flow in a duct or pipe, either:
- Traverse the duct: measure at many points across the area (log-Tchebycheff or equal-area method) and average the velocities.
- Estimate: in fully developed turbulent pipe flow, average velocity is roughly 0.8–0.85 times the centreline velocity.
Then Q = average velocity × cross-section area.
Air density matters
Air density changes with temperature, pressure and altitude:
| Condition | Density (kg/m³) |
|---|---|
| 0 °C, sea level | 1.29 |
| 20 °C, sea level | 1.20 |
| 50 °C, sea level | 1.09 |
| 20 °C, 1,500 m altitude | 1.01 |
Using 1.2 kg/m³ at 50 °C overestimates density by 10% and underestimates velocity by about 5%.
Averaging pitot tubes
Industrial averaging pitot tubes (such as multi-port probes) sample pressure at several points across the pipe and give a DP related to average velocity. They have low permanent pressure loss and suit large pipes and ducts.
Aircraft airspeed
Aircraft use pitot-static systems to measure indicated airspeed from dynamic pressure. At altitude, the lower air density means true airspeed is higher than indicated airspeed.
Measuring tips
- Point the tip straight into the flow, within about ±10°.
- Velocity varies across a duct. For flow measurement, take a traverse — several readings at standard positions — and average the velocities (not the pressures).
- Below about 3 m/s in air, the pressure is very small and readings become unreliable.
Frequently asked questions
How does a pitot tube measure velocity?
It compares the total pressure facing the flow with the static pressure. The difference (dynamic pressure) equals ½ρv², so velocity is √(2ΔP/ρ).
What density should I use for air?
About 1.2 kg/m³ at 20 °C and sea level. Hot air or high altitude is less dense, which gives a higher velocity for the same pressure.
How do I get the flow rate?
Multiply the average velocity by the duct's cross-section area. Use the pipe flow velocity calculator with the measured velocity.
What velocity does 100 Pa of dynamic pressure give in air?
At 1.2 kg/m³: v = √(2 × 100 ÷ 1.2) = 12.9 m/s.
Can a pitot tube measure liquid flow?
Yes. Use the liquid density, for example 998 kg/m³ for water.