1. Why Reference kLa Values Matter
Typical kLa values run 5–20 h−1 for shake flasks, 20–120 h−1 for stirred-tank bioreactors, and up to 300 h−1 in high-agitation microbial fermentation. The table below consolidates 25+ vessel configurations from 96-well microtitre plates through 10,000 L production STRs, all in one place.
The volumetric mass transfer coefficient (kLa) determines how fast oxygen moves from gas to liquid in your bioreactor. Whether you are designing a new process, troubleshooting oxygen limitation, or planning a scale-up, having a reliable set of reference kLa values lets you quickly assess whether your system can deliver the oxygen your culture demands.
Published kLa data is scattered across hundreds of papers, vendor datasheets, and textbooks—often reported in inconsistent units and under different conditions. The table below consolidates the most commonly needed values into a single, searchable reference covering shake flasks through production-scale stirred tanks.
For a deep dive into how kLa is measured and calculated from first principles, see our complete guide: How to Calculate kLa for Any Bioreactor.
2. kLa Reference Table
All values assume aqueous media without antifoam at 20–37°C and standard atmospheric pressure unless noted otherwise. Ranges reflect typical operating windows; extreme conditions can push kLa outside these bounds.
| Vessel Type | Volume | Organism / Media | kLa (h−1) | Conditions | Source |
|---|---|---|---|---|---|
| Shake flask (unbaffled) | 125 mL | Water / E. coli media | 15–60 | 20–50 mL fill, 200–250 RPM, 25 mm orbit | Büchs et al. 2001 |
| Shake flask (unbaffled) | 250 mL | Water / LB media | 10–50 | 25–100 mL fill, 200–250 RPM, 25 mm orbit | Büchs et al. 2001 |
| Shake flask (baffled) | 250 mL | Water / culture media | 40–100 | 50 mL fill, 200–250 RPM, 25 mm orbit | Maier & Büchs 2001 |
| Shake flask (unbaffled) | 500 mL | Water / yeast media | 8–35 | 100–200 mL fill, 180–220 RPM | Maier & Büchs 2001 |
| Shake flask (unbaffled) | 2 L | Water / culture media | 5–20 | 200–500 mL fill, 150–200 RPM | Kluyver & Visser 1950 |
| Microbioreactor (24-well) | 2–5 mL | E. coli / CHO media | 80–300 | 800–1200 RPM, sealed with OTR membrane | Duetz & Witholt 2004 |
| Microbioreactor (ambr 15) | 15 mL | CHO cell culture media | 5–20 | 400–1400 RPM, single impeller | Sartorius data |
| Microbioreactor (ambr 250) | 250 mL | CHO / microbial media | 10–60 | 200–1200 RPM, dual impellers | Sartorius data |
| Wave / rocking bag | 2 L | CHO cell culture media | 5–15 | 15–25 rpm rock, 6–10° angle, 50% fill | Cytiva/GE data |
| Wave / rocking bag | 10 L | Hybridoma / CHO media | 4–20 | 15–35 rpm rock, 6–12° angle, 40–60% fill | Singh 1999 |
| Wave / rocking bag | 50 L | CHO / insect cell media | 3–25 | 20–42 rpm rock, 8–12° angle | Cytiva/GE data |
| STR glass (lab) | 1 L | Water / E. coli media | 40–180 | Rushton, 200–800 RPM, 1 vvm air | Van't Riet 1979 |
| STR glass (lab) | 3 L | Water / yeast media | 50–200 | Rushton, 300–800 RPM, 1–2 vvm air | Van't Riet 1979 |
| STR glass (lab) | 5–10 L | Water / culture media | 50–250 | Rushton, 200–600 RPM, 0.5–2 vvm | Garcia-Ochoa 2009 |
| STR stainless steel | 50 L | E. coli / yeast media | 80–350 | Dual Rushton, 300–600 RPM, 1–2 vvm | Linek 1987 |
| STR stainless steel | 200 L | E. coli / yeast media | 100–400 | Dual Rushton, 150–400 RPM, 1–2 vvm | Garcia-Ochoa 2009 |
| STR stainless steel | 500 L | Culture media | 100–350 | Multi-impeller, 100–300 RPM, 0.5–1.5 vvm | Gezork 2001 |
| STR stainless steel | 2,000 L | CHO / microbial media | 80–300 | Multi-impeller, 80–200 RPM, 0.5–1.5 vvm | Nienow 2006 |
| STR stainless steel | 5,000 L | CHO / microbial media | 100–350 | Multi-impeller, 60–150 RPM, 0.3–1 vvm, +O2 enrichment | Nienow 2006 |
| STR stainless steel | 10,000 L | Production media | 100–400 | Multi-impeller, backpressure 0.5–1.0 bar, O2 enrich. | Garcia-Ochoa 2009 |
| Single-use STR (BIOSTAT STR) | 50 L | CHO cell culture media | 15–60 | Pitched blade, 100–300 RPM, 0.1–0.5 vvm | Sartorius data |
| Single-use STR (XDR) | 200 L | CHO cell culture media | 10–50 | Pitched blade, 60–200 RPM, 0.05–0.3 vvm | Cytiva data |
| Single-use STR | 500–2000 L | CHO / mAb process | 5–40 | Low-shear impeller, 40–120 RPM, 0.02–0.1 vvm | Various vendor data |
| Bubble column | 10–100 L | Water / fermentation media | 20–100 | No agitation, 0.5–3 vvm aeration | Deckwer 1992 |
| Bubble column | 500–5000 L | Industrial fermentation | 30–150 | No agitation, 0.5–2 vvm, tall aspect ratio | Deckwer 1992 |
| Airlift bioreactor | 10–1000 L | Mammalian / microbial | 20–100 | 0.3–1.5 vvm, draft tube or external loop | Chisti 1989 |
| Microtiter plate (96-well) | 0.1–0.3 mL | E. coli / yeast media | 100–400 | 700–1000 RPM, 3 mm orbit, sealed | Duetz & Witholt 2004 |
Notice that kLa does not simply increase with vessel size. Lab-scale STRs can achieve very high kLa values because they operate at high RPM relative to their diameter. At production scale, O2 enrichment and back-pressure are used to compensate for lower achievable agitation intensity.
3. How to Use These Values
Sanity-check your measurements
If you measure kLa in your 5 L STR and get 500 h−1 with a Rushton turbine at 400 RPM, this table tells you that is at the high end of normal—plausible but worth double-checking your probe response time. If you get 5 h−1 under the same conditions, something is wrong: clogged sparger, probe malfunction, or antifoam overdose.
Quick estimation for process design
When designing a new process, you can use these ranges to estimate whether a vessel type will meet your culture's oxygen demand without running experiments. Calculate the required OTR from your expected cell density and specific oxygen uptake rate:
kLarequired = OTRrequired / (C* − CL,setpoint)
where:
qO2 = specific oxygen uptake rate (mmol/g/h)
X = cell density (g/L)
C* = saturated DO (~7 mg/L at 37°C in air)
CL,setpoint = DO setpoint (e.g., 30% = 2.1 mg/L)
If the required kLa falls within the range for your chosen vessel type, you are in good shape. If it exceeds the upper end, you may need a different vessel, higher RPM, O2 enrichment, or back-pressure to bridge the gap.
Scale-up planning
When moving from lab to pilot scale, compare the kLa range of your current vessel with the target vessel. If your 5 L glass STR delivers kLa = 180 h−1 and you are scaling to a 200 L single-use STR (max kLa ~50 h−1), you need to either accept lower oxygen transfer, supplement with O2 enrichment, or choose a stainless-steel vessel instead.
4. Factors That Shift kLa From These Ranges
The values in the table above assume clean aqueous media. Several real-world factors can move kLa significantly outside these ranges:
Antifoam agents
Direction: down 30–60%. Silicone-based antifoams (e.g., Antifoam C, SE-15) create a film at the gas-liquid interface that reduces mass transfer. Polypropylene glycol (PPG) antifoams have a smaller effect (10–30% reduction). Use the minimum effective concentration and add only when foam is actively present.
Viscosity
Direction: down 20–80%. High-viscosity broths (filamentous fungi, polysaccharide producers, high-cell-density E. coli at >50 g/L DCW) suppress turbulence and thicken the boundary layer around bubbles. A 10-fold viscosity increase can halve kLa. Viscosity also increases with cell debris after lysis events.
Temperature
Direction: up ~2% per degree C. Higher temperature increases oxygen diffusivity (raising kL) but decreases oxygen solubility (lowering C*). The net effect on kLa is an increase of roughly 1.5–2.5% per °C. Apply the correction factor: kLaT = kLa20 × 1.022(T − 20).
Media salts and proteins
Direction: up 20–80%. Dissolved salts and proteins inhibit bubble coalescence, producing smaller bubbles with greater total interfacial area. This is why kLa in real culture media is often higher than in pure water, despite slightly higher viscosity. The Van't Riet non-coalescing correlation captures this effect.
Back-pressure and O2 enrichment
Direction: multiply C* proportionally. These do not change kLa itself, but they increase C* (the driving force denominator). At 1 bar back-pressure, C* doubles. At 50% O2 enrichment, C* increases ~2.5-fold. The practical effect is identical to increasing kLa from an OTR perspective.
Do not compare kLa values measured in water with those measured in fermentation media without accounting for the coalescence effect. Water-measured kLa can be 30–50% lower than the same vessel with salted media—even before adding antifoam, which then pushes it back down.
5. Estimate Your Own kLa
This reference table provides quick ballpark estimates, but your specific conditions will determine the exact kLa. Use our free calculators to get precise estimates for your setup.
OTR & kLa Estimator
Enter your vessel type, dimensions, and operating conditions to calculate kLa using the Van't Riet or Büchs correlations.
Estimate kLa Now →For related calculations and deeper background, see these resources:
- How to Calculate kLa for Any Bioreactor — Full derivation of the dynamic gassing-out method and Van't Riet / Büchs correlations with worked examples.
- Scale-Up Calculator — Compare all five scale-up criteria and see how kLa, P/V, and tip speed change across scales.
6. Frequently Asked Questions
What is a typical kLa value for a 2000 L bioreactor?
For a 2000 L stainless-steel stirred-tank bioreactor, typical kLa values range from 80 to 300 h−1 with multi-impeller Rushton or hybrid configurations at 80–200 RPM and 0.5–1.5 vvm aeration. Mammalian (CHO) processes usually sit at the lower end (80–150 h−1) because of shear constraints, while microbial cultures push toward the upper end and are often supplemented with 0.3–0.5 bar back-pressure and O2 enrichment to raise the driving force. Single-use 2000 L STRs typically deliver lower kLa (5–40 h−1) because they use low-shear impellers and reduced sparging.
How does impeller type affect kLa?
Impeller geometry can shift kLa by 2–3x at the same power input. Rushton turbines (radial flow) generate high shear and small bubbles, giving the highest kLa per unit power, typically 100–350 h−1 in a lab-scale STR. Pitched-blade and marine impellers (axial flow) deliver 30–60% lower kLa but are gentler on shear-sensitive mammalian cells. Concave-blade and hydrofoil designs (Chemineer CD-6, Lightnin A315) sit between the two and cope better with high-viscosity broths. Dual or triple impeller stacks in tall vessels raise kLa by 40–80% versus a single impeller at the same tip speed. See the impeller power numbers reference for matched power data.
Why does kLa drop when broth viscosity increases?
High-viscosity broths, common with filamentous fungi, polysaccharide producers, and high-cell-density E. coli above 50 g/L DCW, suppress turbulence around the impeller and thicken the liquid-film boundary layer around each bubble. Both effects lower the liquid-side mass transfer coefficient kL. A 10-fold increase in apparent viscosity typically halves kLa. Bubble coalescence also worsens in viscous media, reducing the interfacial area a. To compensate, increase agitation power per unit volume (P/V), add O2 enrichment, or switch to a hydrofoil or Rushton-Scaba impeller stack designed for viscous duty.
What is the typical kLa range for shake flasks?
Unbaffled shake flasks deliver kLa in the range of 5–60 h−1 depending on fill volume, shaking speed, and orbit diameter. A 250 mL unbaffled flask with 50 mL fill at 200–250 RPM on a 25 mm orbit sits around 10–50 h−1. Baffled flasks roughly double this to 40–100 h−1 by disrupting the free-surface swirl. Fill volume matters more than most operators realise: dropping from 100 mL to 25 mL in a 250 mL flask can increase kLa by 3–5 fold. For head-to-head shake flask calculations, use the OTR & kLa Estimator.