What is Space-Time Yield — and why does it matter?

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Space-Time Yield (STY) measures the mass of desired product a reactor produces per unit volume per unit time, expressed in grams per litre per hour (g·L⁻¹·h⁻¹). Unlike percent yield, which compares what you got to what theory predicts, STY evaluates the productivity of the reactor itself, making it the key metric for comparing batch reactions, continuous flow processes, and industrial-scale manufacturing. A high STY means the same reaction vessel produces more product in less time, reducing energy consumption, solvent use, and capital cost per gram of product.

GoalMaximise product formation per unit reactor volume per unit time, approaching values seen in continuous flow or intensified batch processes.

WhyHigher STY means less reactor volume needed, lower energy costs per gram of product, and reduced solvent and material waste per production run, directly linking process efficiency to green chemistry principles.

HowIncrease reagent concentration, optimise temperature and catalyst loading to shorten reaction time, consider continuous flow over batch, and minimise workup and isolation steps that add to total process time.

The formula

$$\text{STY} = \frac{m_{\text{product}}}{V_{\text{reactor}} \times t_{\text{reaction}}}$$

Symbol	Term	Units
$\text{STY}$	Space-Time Yield	g·L⁻¹·h⁻¹; higher is better
$m_{\text{product}}$	Actual mass of pure, dry desired product isolated	g
$V_{\text{reactor}}$	Total volume of the reaction mixture (solvent + all reagents)	L
$t_{\text{reaction}}$	Reaction time from reagent addition to quench or start of product isolation	h

STY uses the actual mass isolated, not the theoretical maximum. Increasing % yield, increasing reagent concentration, or switching to a faster reaction all increase STY. Unlike Atom Economy, STY is an entirely experimental metric, and it cannot be estimated before running the reaction.

Strengths and limitations

Strengths

Captures real experimental productivity, not a theoretical estimate
Directly comparable across batch, semi-batch, and continuous processes
Highlights inefficiencies from excessive dilution or slow kinetics
Simple to calculate: only mass, volume, and time are needed
Scales directly to industrial throughput metrics
Drives process intensification and adoption of flow chemistry

Limitations

Says nothing about what was used: a high STY from a toxic stoichiometric reagent is still poor green chemistry
Does not capture atom economy, waste composition, or by-product hazard
Sensitive to how "reactor volume" is defined; including workup volumes dramatically changes STY
Does not capture purification time, energy input, or solvent recovery
Favours fast, concentrated reactions regardless of selectivity
Must be paired with E-factor, PMI, and AE for a complete greenness picture

STY in context: complementary green metrics

Metric	What it measures	Stage
Space-Time Yield (STY)	Product mass per reactor volume per unit time (reactor productivity)	Experimental
% Yield	Fraction of theoretical product actually isolated from limiting reagent	Experimental
Atom Economy (AE)	Theoretical fraction of reactant mass incorporated into desired product	Design
E-factor	Mass of all waste per mass of product (solvents, excess, by-products)	Experimental
PMI (Process Mass Intensity)	Total mass of all inputs per mass of product; E-factor + 1	Experimental
RME (Reaction Mass Efficiency)	Combined practical efficiency: AE × yield × stoichiometric factor	Both

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Experiment details

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Experiment / reaction name

Researcher(s)

Date

Lab / institution

Reaction type

Solvent

Temperature

Catalyst / additive

Reference / DOI

Notes

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Reactants

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Enter the mass and molecular weight of each reactant used. The tool identifies the limiting reagent (lowest moles/coefficient ratio) and calculates the theoretical yield for context. Reactant masses appear in the breakdown charts.

Compound name	Formula	MW (g/mol)	Mass used (g)	Coeff.	Moles

Σ Reactant mass — g · Limiting reagent: —

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Product & reaction conditions

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Enter the desired product, then the actual mass isolated and the reaction conditions. STY = product mass ÷ (reactor volume × reaction time).

Product name	Formula	MW (g/mol)	Coeff.	MW × n

Actual mass of product isolated

Enter the mass of pure, dry product actually isolated from your experiment.

Reactor volume

Total volume of the reaction mixture, including solvent and all reagents.

Reaction time

Reaction time from reagent addition to quench or start of product isolation.

V × t factor — L·h · Theoretical yield: — g (from limiting reagent)

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Results

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Space-Time Yield

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g·L⁻¹·h⁻¹

Product Mass

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g isolated

V × t Factor

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L·h

Σ Reactant Mass

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g

STY scale: 0 to ≥ 200 g·L⁻¹·h⁻¹ (higher is better)

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050100150≥200 g·L⁻¹·h⁻¹

Reactant mass contributions

Actual vs. theoretical product mass

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Detailed breakdown & interpretation

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Compound	Role	Formula	MW (g/mol)	Mass (g)	Moles	Coeff.	% of total mass	Visual
Enter reactants and product above to see breakdown.

Interpretation

Enter reactant masses, product details, reactor volume, and reaction time above to generate an interpretation.

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Save & load sessions

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Sessions are stored in your browser only. No data leaves your device.

No saved sessions yet.

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Export

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Export your Space-Time Yield calculation as a PDF report or CSV data file. PDF opens in a new tab and uses your browser's print function. CSV downloads directly.

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Where can I read more?

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References are sorted alphabetically by first author.

P. T. Anastas and J. C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 1998. ISBN 978-0-19-850698-0. Original statement of the 12 Principles; frames energy efficiency as Principle 6.
J. Andraos, "Assessing the Sustainability of Syntheses of the Anti-tuberculosis Pharmaceutical Pretomanid by Green Metrics", in Sustainable Organic Synthesis: Tools and Strategies, ed. S. Protti and A. Palmieri, Royal Society of Chemistry, 2021, pp. 1–21. Link. Worked case study applying space-time yield alongside other green metrics to a pharmaceutical synthesis.
D. J. C. Constable et al., Green Chem., 2002, 4, 521–527. DOI. Metrics to "green" chemistry: formally introduces space-time yield as a green chemistry metric.
C. Jiménez-González et al., Org. Process Res. Dev., 2011, 15, 912–917. DOI. Using the right green chemistry metric to evaluate the greenness of a chemical process; discusses STY in context of PMI.
T. Newhouse, P. S. Baran and R. W. Hoffmann, Chem. Soc. Rev., 2009, 38, 3010–3021. DOI. The economies of synthesis; discusses step economy and throughput.
M. Poliakoff et al., Science, 2002, 297, 807–810. DOI. Green chemistry: science and politics of change; context for process intensification.
R. A. Sheldon, Green Chem., 2017, 19, 18–43. DOI. The E-Factor 25 years on: metrics landscape including STY and comparisons across industries.

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Contributors

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Roles follow the CRediT taxonomy (Contributor Roles Taxonomy), adapted for educational software. Hover a contributor's name for a summary, or a column header for the definition of that role.

Contributor

This portal was built with the assistance of a large language model (Claude, Anthropic), which was used to generate and refine code, articulate and structure contributed ideas within the defined page format, and support iterative design decisions. All scientific content, conceptual frameworks, pedagogical choices, and final outputs were directed, reviewed, and verified by the contributors listed above.

Whilst every effort has been taken to ensure accuracy, mistakes can happen. If you notice something that doesn’t look quite right, kindly reach out to the DodecaGreen team via the Contact page.

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How do I cite this page?

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If you use this tool in teaching or published work, please cite the DodecaGreen portal as the source.

Reference

BibTeX

Space‑time yield calculator.