Bioconcentration Factor Calculator

Calculator Inputs

Chemical name (optional)

Used in exports and reports.

Organism / species (optional)

Helps track datasets across studies.

Organism concentration

Enter measured tissue concentration.

Organism unit

Choose a wet-weight or reporting unit.

Water concentration

Enter dissolved or measured water concentration.

Water unit

Unit is normalized internally for calculations.

Options

Compute log10 outputs

Lipid-normalize organism concentration

Turn on lipid normalization when lipid fraction is known.

Lipid fraction (0–1)

Only used when lipid normalization is enabled.

Screening thresholds (optional)

Set your own cutoffs to label results.

Notes (optional)

Reset

After submitting, the result appears above this form.

Example data table

Chemical	Organism	C_organism	C_water	Lipid fraction	BCF (L/kg)	log10(BCF)
Example A	Fish	2.5 mg/kg	0.01 mg/L	0.05	250.0	2.3979
Example B	Algae	1200 ug/kg	50 ug/L	—	24.0	1.3802
Example C	Mussel	0.8 ug/g	200 ng/L	0.02	4000.0	3.6021

Example values are for demonstration of unit handling and reporting.

Formula used

Standard BCF (steady-state)

BCF = C_organism / C_water

If C_organism is in mg/kg and C_water is in mg/L, the result is in L/kg.

Lipid-normalized BCF (optional)

BCF_lipid = (C_organism / f_lipid) / C_water

Use when lipid fraction (f_lipid) is known and you want lipid-basis reporting.

Log transform (optional)

log10(BCF) = log10(BCF)

Useful for comparing across wide ranges of accumulation.

How to use this calculator

Enter the organism concentration and select its unit.
Enter the water concentration and select its unit.
Enable lipid normalization if you have lipid fraction data.
Optionally set custom thresholds to label the result.
Click Submit to display results above the form.
Download a CSV or PDF summary for documentation.

Technical article

What BCF quantifies in monitoring programs

Bioconcentration factor summarizes how strongly a substance partitions from water into an organism under aquatic exposure. It is most informative when tissue and water samples represent the same place and time window. Steady-state designs typically use constant concentrations until tissue plateaus, but time-weighted sampling can still be summarized if you document the averaging period. Record temperature, salinity, and organism size class, because these factors affect uptake rates and tissue composition across sites more reliably. For example, 2.5 mg/kg in fish with 0.01 mg/L in water yields 250 L/kg, indicating notable accumulation compared with more weakly sorbing chemicals.

Unit normalization and comparable reporting

Field datasets arrive in mixed units, so consistent conversion prevents order of magnitude errors. This calculator normalizes organism concentration to mg/kg and water concentration to mg/L, producing L/kg automatically. If a laboratory reports 1200 µg/kg and the water sample is 50 µg/L, the normalized ratio is 1.2 mg/kg ÷ 0.05 mg/L = 24 L/kg.

Lipid basis adjustments for hydrophobic chemicals

Lipid content influences tissue residues for hydrophobic compounds, so two samples with identical exposure can differ if lipid fractions differ. Lipid normalization divides tissue concentration by the lipid fraction (f_lipid). Using 0.8 µg/g (0.8 mg/kg) with f_lipid=0.02 gives 40 mg/kg-lipid; with 200 ng/L (0.0002 mg/L), BCF_lipid becomes 200,000 L/kg-lipid.

Interpreting results with screening thresholds

BCF is often used as a screening metric rather than a final hazard conclusion. Many programs classify results using internal thresholds, then prioritize follow-up for higher categories. A log10 transform helps visualize wide ranges: 24 L/kg corresponds to log10(BCF)=1.3802, while 4000 L/kg corresponds to 3.6021. When you enter low and high thresholds, the calculator labels the result to support consistent triage.

Data integrity checks before exporting reports

Ensure that water concentrations reflect the same fraction reported for tissue (dissolved, total, or filtered) and note matrix and method in the optional notes field. Outliers can arise from short exposures, depuration, growth dilution, or analytical interference. Replicate sampling, blank corrections, and detection limit handling improve comparability. Exported CSV and PDF outputs preserve both inputs and normalized values so reviewers can reproduce calculations quickly.

FAQs

1) What is the difference between BCF and BAF?

BCF describes uptake directly from water only. BAF includes all exposure routes, including diet and sediment, so it is usually larger for bioaccumulative chemicals and depends on food-web position.

2) Should I use dissolved or total water concentration?

Use the water fraction that matches your study design and interpretation. Dissolved measurements are common for partitioning comparisons, while total concentrations may be appropriate when organisms experience particulate-bound chemicals.

3) How should I handle results below detection limits?

Avoid dividing by zero. Document the detection limit and apply a consistent substitution rule, such as half the limit, only if allowed by your protocol. Sensitivity checks with multiple substitutions help show uncertainty.

4) Can I calculate BCF using dry-weight tissue data?

Yes, but be consistent. Convert dry-weight concentrations to wet-weight or clearly label the basis in notes and exports. Mixing bases across samples can distort comparisons more than the calculation itself.

5) Why provide log10(BCF) outputs?

BCF values can span several orders of magnitude. The log10 scale compresses that range, supports clearer plotting, and aligns with common screening workflows that compare classes of accumulation.

6) Which lipid fraction should I enter for normalization?

Use the measured lipid fraction for the same sample or a representative mean for the same species, season, and tissue type. Report the source and method, because small differences in lipid fraction can shift lipid-basis BCF substantially.