Total Pressure from Static and Velocity Calculator

Example Data Table

Values are rounded for readability.

Formula Used

For incompressible flow along a streamline, total (stagnation) pressure is the sum of static pressure and dynamic pressure:

• q = ½ ρ v² (dynamic pressure)
• Pt = Ps + q (total pressure)

If density is computed from gas properties, the calculator uses ρ = P/(R·T) with absolute pressure.

How to Use This Calculator

1. Enter the static pressure and select its unit.
2. Enter the flow velocity and select its unit.
3. Pick a density method: direct input, or ideal gas.
4. If using ideal gas, provide absolute pressure, temperature, and R.
5. Choose decimal places, then press Calculate.
6. Download CSV or PDF to save the computed results.

Keep pressure references consistent: gauge inputs produce gauge totals.

Professional Article

1) What total pressure represents

Total pressure, also called stagnation pressure, is the pressure a moving fluid would have if it were brought to rest without losses. In practical diagnostics, it links a measured static pressure to the energy associated with flow speed. When you add dynamic pressure to static pressure, you obtain the total pressure that appears in Pitot measurements, inlet assessments, and wind‑tunnel test points.

2) Static, dynamic, and total pressure relationship

The calculator applies Pt = Ps + q, where q = ½ρv². For air near sea level, density is often around 1.225 kg/m³. At 20 m/s, dynamic pressure is roughly 245 Pa, so a static pressure of 101,325 Pa becomes about 101,570 Pa. This small rise is normal for low‑speed airflows.

3) Interpreting results across typical ranges

Dynamic pressure scales with the square of velocity. Doubling speed increases q by a factor of four. For example, with ρ = 1.2 kg/m³, v = 50 m/s produces q ≈ 1,500 Pa. In water, where density is near 998 kg/m³, even 10 m/s yields about 49,900 Pa, which is a much larger contribution to total pressure.

4) Why density choice matters

Density is the sensitivity knob for dynamic pressure. The direct‑input option is ideal when fluid properties are known from specification, laboratory measurement, or a standard reference. The ideal‑gas option estimates density using ρ = P/(R·T) from absolute pressure and temperature, which is helpful for air systems where conditions vary with altitude, HVAC ductwork, or compressor inlets.

5) Units and conversions you should verify

Mixing units is a common source of error. This tool converts velocity to m/s internally and pressure to Pa before computing results, then converts back to your selected output unit. For troubleshooting, compare the “converted” reference values shown in the results. This is especially useful when working with psi, atm, or inH2O in field measurements.

6) Practical applications in measurement and design

Total pressure is used in Pitot‑static calculations, inlet recovery checks, fan performance curves, and assessing pressure losses across filters and ducts. In wind‑tunnel work, reporting static and total pressure enables consistent comparison between runs. In industrial air systems, the difference Pt − Ps provides a direct estimate of velocity head, supporting flow estimation when geometry is known.

7) Validity limits and compressibility notes

The formula here is the incompressible Bernoulli form. For gases at higher Mach numbers (often above about 0.3), compressibility can increase the gap between true stagnation pressure and the simple Ps + ½ρv² estimate. If your flow is very fast, strongly heated, or involves shocks, use compressible relations and account for losses.

8) Reporting and documentation workflow

After calculating, export results to CSV for spreadsheets and logs, or to PDF for test records and client reports. A clean record should include static pressure, velocity, density method, and the computed dynamic and total pressures. When repeating measurements, keep the same reference (gauge or absolute) and note the temperature if density is derived from gas properties.

FAQs

1) Is total pressure the same as stagnation pressure?

Yes. In lossless deceleration to zero velocity, total pressure equals stagnation pressure. Real systems may have losses, so measured values can be slightly lower.

2) Can I use gauge pressure for static pressure?

You can. If static pressure is gauge, the reported total pressure is also gauge because the dynamic term is independent of the reference baseline.

3) What density should I use for air?

Near sea level and 15°C, a common value is about 1.225 kg/m³. If temperature or pressure differs significantly, compute density using the ideal‑gas option.

4) Why does dynamic pressure increase so fast with speed?

Because dynamic pressure is proportional to velocity squared. A 2× increase in speed produces a 4× increase in dynamic pressure, holding density constant.

5) When should I avoid using this calculator?

Avoid it for high‑Mach compressible flows, strong heating, or shock waves. In those cases, compressible stagnation relations and loss models are needed.

6) Does fluid type matter beyond density?

For this calculation, density is the main property. Viscosity affects losses and boundary layers, but the ideal Bernoulli total pressure relation uses density and velocity only.

7) How accurate are the unit conversions?

Conversions use standard factors for Pa, bar, atm, psi, mmHg, and common velocity units. Minor variations can exist for inH2O with temperature, so note your reference conditions.

Use this tool to estimate total pressure quickly, accurately\.