Compute hydraulic resistance, pressure drop, and Reynolds number for tubing or chip channels. Get a pump class recommendation before you plumb the rig. Free. Client-side.
Try it out
Load example microfluidic pressure drop calculator data to see the full workflow
When to use
Do not use for
Halving the tubing ID multiplies resistance by 16×. The biggest single driver of ΔP in any microfluidic system is the narrowest segment — usually the chip channel itself.
Tubing → connector → chip → tubing → outlet: sum the Rs. Parallel channels on a single chip: use 1/Rtotal = Σ 1/Ri. Compute each geometry separately and combine.
A syringe pump rated "up to 200 mbar" usually means "can generate 200 mbar against a blocked outlet". In practice, derate by 2× — plan your rig for half the rated pressure as a safety margin.
The Bahrami formula is accurate within ~3% for h/w < 0.5 and within ~10% for square channels. For critical work use the full Fourier series solution.
Hagen-Poiseuille for circular channels: R = 8μL/(π). Rectangular channels: Bahrami low-aspect-ratio approximation R = 12μL/[(1 − 0.63 h/w)]. Wall shear stress: τ = 6μQ/() (rectangular) or τ = 4μQ/(π) (circular). Tubing resistance computed as series resistance and added to channel resistance for total system ΔP. Reynolds number from ρvD/μ (circular) or using hydraulic diameter D_h = 2wh/(w+h) (rectangular). Pump class thresholds: <100 mbar syringe, 100–1000 mbar low-pressure controller, >1000 mbar high-pressure controller. Temperature-dependent water viscosity from NIST REFPROP.
Last validated 2026-04-07. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
ConductScience Microfluidic Pressure Drop & Flow Planner (v2.0.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/microfluidic-pressure-drop-calculator
Every microfluidic pump has a maximum pressure rating. If the ΔP your rig demands exceeds what the pump can deliver, the actual flow rate will be lower than the setpoint — sometimes dramatically lower, sometimes zero. This is the single most common source of "my flow rate is wrong" problems in microfluidics.
Syringe pumps typically deliver 100–200 mbar of driving pressure before stalling. Pressure-driven controllers like Fluigent and Elveflow go to 1–2 bar routinely. Specialty high-pressure systems (HPLC-style) reach 10+ bar.
Hagen-Poiseuille resistance scales as 1/. This is the single most counterintuitive fact in microfluidics.
Cutting your tubing ID in half multiplies ΔP by 16. Going from 1 mm ID to 0.5 mm ID turns a 50 mbar system into an 800 mbar system at the same flow rate. Many labs discover this the hard way when they "upgrade" to narrower tubing to reduce dead volume and find the pump can no longer drive the flow.
In the laminar regime (Re < 2000), ΔP scales linearly with viscosity and linearly with flow rate. Switching from water (1 mPa·s) to 50% glycerol (6 mPa·s) multiplies ΔP by 6× — same tubing, same flow rate.
Temperature also matters: water at 37 °C is 31% less viscous than at 20 °C, so running a cell-culture perfusion at body temperature cuts pump load meaningfully compared to room-temperature benchmarks.
Syringe pumps and pressure controllers sized for the ΔP range your rig demands
Browse EquipmentPEEK, PTFE, FEP, and Tygon tubing in every standard ID
Browse QuoteGet a quote on equipment or talk to the ConductScience team.
Request quote