Biology data, not black-box answers
Free Biology Calculators
with Full Working
Microscopy, statistics, ecology, genetics and experimental data — with the calculation steps between your values and the final answer.
4 calculators
Microscopy & measurement
Magnification, scale bars, field-of-view density and surface-area-to-volume calculations used throughout practical biology.
Magnification & actual size
Calculate magnification, image size or actual size with automatic mm–µm–nm conversion and full working.
Open calculatorScale bar actual size
Use a micrograph scale bar to calculate actual specimen size without relying on the displayed magnification.
Open calculatorField-of-view density
Estimate cell or stomatal density from a count within a circular microscope field of view.
Open calculatorSurface area : volume
Calculate surface area, volume and SA:V ratio for cubes, spheres and cylinders.
Open calculator6 calculators
Statistics & graphs
Process replicate data, quantify spread, test hypotheses and analyse relationships with r, R² and regression.
Mean, median, mode & range
Summarize biological replicate data with n, mean, median, mode, minimum, maximum and range.
Open calculatorSD & standard error
Calculate sample and population standard deviation plus standard error of the mean for replicate measurements.
Open calculatorError bar ranges
Convert a mean and SD, SE or other symmetric error into lower and upper error-bar limits.
Open calculatorRegression, r & R²
Fit a straight line to paired biological data and calculate slope, intercept, Pearson r and R² with a graph.
Open calculatorTwo-sample t-test
Compare two biological samples with an independent Welch t-test or paired t-test and report t, df and two-tailed p.
Open calculatorChi-squared test
Calculate χ², degrees of freedom and an approximate p-value for goodness-of-fit data or a 2×2 association table.
Open calculator5 calculators
Ecology & populations
Estimate population size and density, quantify biodiversity, energy transfer and population change.
Lincoln index
Estimate population size from capture–mark–release–recapture data using the Lincoln index.
Open calculatorSimpson reciprocal index
Calculate the Simpson reciprocal diversity index from species abundance counts.
Open calculatorQuadrat population estimate
Calculate mean quadrat count, density and a simple habitat population estimate from random quadrat samples.
Open calculatorEnergy transfer efficiency
Calculate ecological energy-transfer efficiency between trophic levels or biological processes.
Open calculatorPopulation growth
Calculate absolute change, average growth rate and percentage population change over a time interval.
Open calculator3 calculators
Genetics & evolution
Work with allele frequencies, Hardy–Weinberg predictions and recombination data.
Hardy–Weinberg
Calculate allele and genotype frequencies under Hardy–Weinberg equilibrium from q², p², p or q.
Open calculatorAllele frequency
Calculate two-allele frequencies from AA, Aa and aa genotype counts.
Open calculatorRecombination frequency
Calculate recombination frequency and map distance estimate from offspring or gamete counts.
Open calculator7 calculators
Experimental data & uncertainty
Paper 1B-friendly tools for rates, percentages, uncertainty, significant figures, dilution and calibration data.
Rate of change
Calculate average biological rate of change from two measurements and an elapsed time.
Open calculatorPercentage change & difference
Calculate signed percentage change or symmetric percentage difference between biological measurements.
Open calculatorPercentage uncertainty
Convert an absolute measurement uncertainty into percentage uncertainty and format the measurement.
Open calculatorSignificant figures
Round a value to a chosen number of significant figures and explain how zeros are treated.
Open calculatorDilution
Solve C₁V₁ = C₂V₂ for a simple laboratory dilution using any consistent concentration and volume units.
Open calculatorSerial dilution
Calculate concentrations through repeated equal-factor serial dilution steps.
Open calculatorCalibration curve
Fit a linear calibration curve, report R² and estimate an unknown biological sample from its response.
Open calculatorUseful for checking. Better for learning the logic.
Every calculator includes the relationship, defined variables, a worked example and common mistakes. Paper 1B pages focus on data analysis and experimental reasoning rather than reproducing examination questions.
Read the calculation conventions