Evidence Lab
Hands-on calculators and demonstrations that let you explore the math behind forensic methods. Each tool explains its formula and what the result means.
Educational demonstrations only. These calculators use simplified formulas to teach concepts. They are not professional investigative tools and must never be used to draw real-world conclusions about actual people or cases.
Bloodstain Angle of Impact
Estimate the angle at which a blood drop struck a surface from the shape of the resulting stain. A drop hitting at 90° is round; lower angles produce more elongated stains.
Postmortem Interval
A common question is "when did death occur?" There is no simple formula that answers it. Estimating the postmortem interval combines several signs, each imprecise, and no single one determines time of death.
Think like a scientist: each sign (rigor, livor, cooling, insects) gives a rough, overlapping window — not a precise time. Combining several independent signs narrows the interval more than any one alone.
This is why the Evidence Lab has no time-of-death calculator: an exact answer would imply a certainty the science does not support.
DNA Random Match Probability
Multiply the frequencies of several independent DNA markers to see how quickly a combined profile becomes rare. This illustrates why many loci create powerful (but not absolute) evidence.
3 factors combined. More independent markers shrink the probability fast — but a small number never proves uniqueness.
Population Genetics (Hardy-Weinberg)
Given the frequency of one allele (p), the Hardy-Weinberg principle predicts the expected genotype frequencies in an ideal population — the basis for allele-frequency reasoning in DNA statistics.
These three genotype frequencies sum to 1 (100%) in an ideal population.
Dilution (C₁V₁ = C₂V₂)
Find the final volume needed to dilute a solution from one concentration to another. Widely used in lab preparation, including toxicology and chemistry work.
Unit Converter
Convert common forensic-relevant units: temperature, length, and mass. Useful for moving between laboratory and field measurements.
A single "time of death" calculator has been intentionally removed. Estimating the postmortem interval depends on many interacting factors — temperature, environment, rigor and livor mortis, decomposition, and insect activity — and no simple formula can determine it accurately. See the Postmortem Interval field note above for why.
