Science & engineering calculators

A

• A260 Calculator (DNA/RNA Concentration & Purity).
  Use A260/A280/A230 and dilution to estimate DNA/RNA concentration (ng/µL) plus A260/280 and A260/230 purity ratios.
• Acid-base titration curve & pH.
  Compute pH during acid-base titrations and generate titration curves.
• Acid-base titration curve simulator.
  Plot pH versus added volume for strong/weak acid-base systems, highlight key points, and export CSV or share URL.
• Acid–base pH.
  Solve acid–base pH for strong and weak acids and bases, plus strong acid–strong base mixtures.
• Angular separation and position angle calculator.
  Compute angular distance and Position Angle (PA) between two sky coordinates. Calculated in your browser. Inputs.
• AQI (Air Quality Index) Calculator (US EPA).
  Convert 24-hour PM2.5 and PM10 concentrations (µg/m³) to US EPA AQI. Check category, breakpoints, truncation.
• Astronomy calculators.
  Astronomy hub for time conversion, observability checks, imaging setup, session planning, and finder chart generation.
• Astronomy Session Planner.
  Plan one-night observing sessions by ranking targets with shared constraints, timeline views, and CSV/JSON export.
• Astronomy Workspace Pro.
  Manage observing projects in one workspace, keep shared location/date/equipment settings, and open linked astronomy.

B

• Beer-Lambert law & calibration curve.
  Compute absorbance, concentration, molar absorptivity, path length, and calibration curves with Beer-Lambert steps.
• Beta diversity calculator (Jaccard / Bray–Curtis).
  Compute beta diversity between samples using Jaccard (presence/absence) or Bray–Curtis (abundance).
• Biology calculators.
  Biology calculators for PCR, cloning, NGS, ecology, and genetics, with quick paths that help you choose the right.
• Buffer pH (Henderson-Hasselbalch).
  Compute buffer pH with Henderson-Hasselbalch, design target-pH mixtures, and estimate acid/base addition effects.

C

• calc of dew point temperature, wet bulb temperature.
  Calculates dew point temperature, wet bulb temperature, sensible temperature (heat index/wind chill), etc.
• Calculate epicenter distance and occurrence time from P.
  The epicenter distance is roughly estimated from the arrival time difference between P waves and S waves (S-P).
• Calorimetry calculator.
  Calculate heat, specific heat, temperature change, and final equilibrium temperature for two-substance calorimetry.
• Catalog Resolver Pro Calculator.
  Offline catalog resolver for M/NGC/IC/C IDs with filters, sorting, multi-select, CSV import, and CSV/JSON export.
• Catalyst loading (mol%, ppm, eq).
  Convert catalyst loading between eq, mol% and ppm/ppb and compute mass, volume, or stock amounts from a base.
• Cell seeding calculator | cells/well → required volume.
  Calculate required cell suspension and media volume from target cells/well (or cells/cm²), number of wells, volume.
• Centrifuge converter (rpm ↔ RCF ×g) | by rotor radius.
  Convert between centrifuge speed (rpm) and relative centrifugal force (RCF, ×g) using rotor radius (mm/cm/in).
• CFU/mL Calculator | Dilution Factor, Plated Volume &.
  Calculate CFU/mL from colony count, dilution factor, and plated volume.
• Chemical Equation Balancer + Stoichiometry.
  Balance reactions via nullspace Gauss-Jordan with transparent steps, then compute limiting reagent, theoretical.
• Chemical equilibrium ICE table (Kc/Kp).
  Build ICE tables from Kc/Kp and initial conditions, solve the extent with a 5% small-x check, and share the setup.
• Chemistry Calculators.
  Chemistry calculators for pH, titration curves, kinetics, equilibrium, and solutions. Step-by-step and browser‑only.
• Circular motion & centripetal force calculator.
  Calculate centripetal acceleration, force, angular speed, period, frequency, and banked-curve angle with formulas.
• Colligative properties (ΔTb, ΔTf, π).
  Compute boiling-point elevation, freezing-point depression and osmotic pressure, or estimate molar mass.
• Concentration & pH Calculator (Step-by-Step).
  Covers molarity, mass percent, dilution, mixing, w/w→M, and strong/weak acid-base or buffer pH with 25 °C.

D

• Dimensional analysis & unit consistency checker.
  Check unit consistency, parse compound units, and build Buckingham Pi groups with step logs and shareable results.
• Distance Modulus Calculator (m, M, d).
  Solve distance modulus for m, M, or distance from m−M = 5 log10(d/10 pc).
• Distance/azimuth calculator for two latitude.
  Calculate the distance and direction (initial/terminal) from the latitude and longitude of two points.
• Diversity index calculator (Shannon & Simpson).
  Calculate diversity indices from category counts.
• DNA/RNA Concentration Converter.
  Convert DNA or RNA concentration between ng/µL, nM, and copies/µL from fragment length and type.
• DO Saturation and BOD/COD Calculator.
  Calculate the saturation concentration and % saturation of dissolved oxygen (DO) from water temperature, salinity.

E

• Earth Science and Environment Calculators.
  Browse earth science and environment calculators with practical step-by-step outputs.
• Earthquake b-value calculator (Gutenberg-Richter).
  Load an earthquake CSV or TSV catalog, build a cumulative frequency-magnitude distribution, and estimate.
• Earthquake Energy Calculator: Magnitude Comparison.
  Use this earthquake energy calculator to compare two magnitudes and estimate how much more energy a magnitude 7.
• Effective chimney height (simple plume rise) calc tool.
  Approximate plume rise Δh and effective chimney height He using the Briggs formula (simplified).
• Electricity CO₂ emissions calc (kWh→kg-CO₂ conversion).
  Estimate CO₂ emissions from electricity from the amount of electricity (kWh/Wh/MWh) and the emission factor.
• Electrochemical cell & Nernst equation.
  Explore standard cell potentials E°, ΔG°, K, Nernst equation E, and concentration cells with steps.
• ELISA standard curve fitter (4PL/5PL).
  Fit 4PL/5PL curves to ELISA standards, estimate unknown concentrations, and review weighting, residuals.
• Empirical & molecular formula.
  Derive empirical and molecular formulas from composition, combustion, or hydrate data with step logs and CSV export.

F

• Field Rotation Planner.
  Plan parallactic angle and field rotation rate through the night, with optional exposure limit estimate.
• Finder Chart Pro Calculator.
  Build finder charts from Right Ascension (RA) and Declination (Dec) with grid, scale bar, orientation markers.

G

• Gaussian Plume Concentration Calculator.
  Estimate concentration C(x,y,z) from a point source with a steady Gaussian plume model.
• Genetic drift simulator (Wright–Fisher) | allele.
  Simulate genetic drift with the Wright–Fisher model.
• Geothermal gradient/heat flow (geothermal) calc.
  Calculate the geothermal gradient dT/dz from two depth points (z1, z2) and two temperature points (T1, T2).
• Gibson Assembly Calculator & DNA Assembly Mix.
  Plan Gibson or Golden Gate DNA assembly mixes.
• Growth curve fitter (exponential & logistic).
  Fit exponential and logistic growth to time-series data and estimate growth rate r, doubling time, and carrying.

H

• Hardy-Weinberg equilibrium calculator (expected frequency.
  Calculate allele frequencies, expected genotype frequencies, χ², and p-value from observed AA/Aa/aa counts.
• Hemocytometer calculator (cells/mL & viability).
  Calculate cell concentration (cells/mL) and viability (%) from hemocytometer counts and dilution.
• Horizon Distance Calculator & Earth Curvature Drop.
  Use this horizon distance calculator to estimate how far you can see from height, mutual visibility distance, earth.

I

• IC50/EC50 calculator (4PL/5PL curve fit) | Dose–response.
  Paste concentration–response data and estimate IC50/EC50 (the 50% point) with 4PL/5PL curve fitting.
• Ideal Gas Law Calculator with Steps.
  Solve PV=nRT, combined gas laws, and gas density or molar mass with automatic unit conversion.
• Imaging Planner (FOV, Pixel Scale, Resolution).
  Plan imaging setup with Field of View (FOV), pixel scale, diffraction limits, and seeing-based sampling guidance.

J

• Julian date (JD/MJD) calculator.
  Convert local date/time and timezone to Coordinated Universal Time (UTC)-based JD and MJD instantly.

K

• Kd calculator | Binding curve fit (one site / Hill).
  Fit binding data with one-site or Hill models to estimate Kd.
• Kepler's Third Law Calculator.
  Use Kepler third law (T^2 = a^3/mu) to solve orbital period or semi-major axis.
• Kinematics: SUVAT / Projectile / Free Fall (steps).
  Solve SUVAT unknowns, 2D projectile motion and free-fall on one page.

L

• Lens & Mirror Ray Diagram Calculator.
  Compute image distance, magnification, and rays for thin lenses or mirrors with steps and a live diagram.
• Lens and mirror equation & magnification calculator.
  Solve thin-lens and spherical-mirror equations to get image distance, magnification, and image type with steps.
• Ligation molar ratio calculator | Vector:insert amounts.
  Calculate required insert mass (ng) and volume (µL) from vector mass, length, and desired molar ratio (e.g., 1:3).
• Limiting reagent & yield.
  Balance reactions and compute limiting reagent, theoretical yield, percent yield, and sample purity with steps logs.

M

• Mendelian ratio chi-square test calculator.
  From observed counts and expected ratios (3:1, 9:3:3:1, etc.), calculate χ², df, and p-value.
• Michaelis–Menten fitter (Km, Vmax) | nonlinear fit.
  Estimate Km and Vmax by nonlinear fitting of the Michaelis–Menten equation from substrate [S] and initial rate v.
• MOI Calculator (Multiplicity of Infection & Infection Rate.
  Calculate MOI from cell count, infectious titer, and inoculum volume.
• Moment magnitude Mw calc (fault→M0→Mw).
  Calculate the seismic moment M0 and moment magnitude Mw from the fault length, width, average slip, and rigidity.
• Momentum & 1D collision calculator.
  Solve 1D collisions with momentum conservation and restitution to get final velocities and energy change with steps.
• Moon visibility (altitude, rise/set, illumination).
  Compute moon altitude curve, moonrise/moonset, transit, moon age, and illumination fraction for a selected date.
• Mosaic Planner Pro Tool.
  Generate NxM mosaic panel centers from target, Field of View (FOV), overlap, and Position Angle (PA) using gnomonic.
• Multistep yield planner.
  Plan multistep syntheses, compute overall yield forward/backward, and highlight bottlenecks.

N

• NGS coverage calculator (average depth).
  Estimate average NGS coverage depth.
• NGS library concentration (ng/µL → nM) | dilution.
  Convert NGS library concentration from ng/µL and fragment length to nM, then calculate normalization dilutions.
• Noise calc (dB addition/distance attenuation).
  You can add dB of multiple sound sources, attenuate by distance (estimate free sound field), and back-calculate.
• Nutrient load calculator (concentration, flow, time).
  Estimate total load (kg) from concentration, flow rate, and period.

O

• Observability time plotter.
  Plan when a target is observable with altitude, twilight, air mass, and moon conditions on a single timeline.
• Ohm's law and simple DC circuit calculator.
  Calculate voltage, current, resistance, power, and simple series/parallel equivalents with steps Ohm's law formulas.
• Open channel (Manning method) flow velocity/flow calc.
  Estimate open-channel flow velocity and discharge with Manning method for rectangular, trapezoidal, and circular.

P

• Partial pressure & gas mixing.
  Apply Dalton's law, two-tank mixing, and wet-gas corrections with step logs and optional van der Waals comparison.
• PCR master mix calculator | reactions, concentrations.
  Calculate PCR/qPCR master mix volumes from reaction volume/count and stock/final concentrations.
• PCR Primer Tm Calculator | Melting & Annealing Temperature.
  Calculate primer melting temperature (Tm) and PCR annealing temperature (Ta) from DNA sequences.
• Physics Calculator Hub: Motion, Waves, Optics.
  Physics calculator hub for mechanics, waves, optics, gases, thermal topics, and circuits.
• Planet Observation Planner.
  Plan planet observation windows with altitude curves, twilight overlay, moon impact, best-window extraction.
• Polar Alignment Pro Calculator.
  Compute pole-star reticle angle, clock position, and time-series drift for practical polar alignment in the field.
• ppm/ppb ↔ mg/m³ conversion (gas).
  ppm/ppb (volume mixing ratio) and mg/m³ (mass concentration) are calculated mutually by specifying temperature.
• Pressure Altitude Calculator (Pressure ↔ Altitude).
  Estimate altitude from atmospheric pressure, pressure from altitude, or sea-level pressure from local readings.
• Projectile motion calculator.
  Calculate time of flight, range, maximum height, and required launch speed for a target with projectile-motion steps.
• Protein standard curve calculator (BCA / Bradford).
  Build a protein assay standard curve for BCA or Bradford data, fit linear or quadratic models, and estimate unknown.
• Punnett square generator (1- and 2-gene).
  Generate a Punnett square from parent genotypes (AA/Aa/aa, AaBb, etc.) and summarize genotype proportions (%/ratio).

Q

• qPCR standard curve calculator.
  Build a qPCR standard curve from Quantity and Ct, calculate slope, intercept, R², and PCR efficiency (%).

R

• RA/Dec to Alt/Az calculator + daily altitude curve.
  Compute single-time Altitude and Azimuth (Alt/Az) and plot a 24-hour altitude curve with CSV export.
• Radioactive decay/dating calculator.
  Calculate the elapsed time (age) from the half-life and survival rate (N/N0, %).
• Rainfall to Volume and Flow Rate Converter.
  Convert rainfall (mm) and area into water volume (m³).
• RC / RL / RLC Calculator — time constant, cutoff.
  Analyse RC, RL, and RLC networks with steps formulas.
• Reaction kinetics & half-life.
  Analyse integrated rate laws, half-lives, 0th/1st/2nd order fits and Arrhenius plots for simple reaction kinetics.
• Reagent table & reaction scale.
  Build reagent tables from a base amount, convert equiv/mol%/ppm to mmol, grams, and mL, then export or share.
• Resistor Color Code Calculator (4/5/6 Band).
  Decode 4/5/6-band resistor color codes (or get colors from a value).

S

• Science & Engineering Calculators.
  Browse science and engineering calculators for physics, chemistry, astronomy, and electronics.
• Sidereal time (GMST/LST) calculator.
  Get Greenwich Mean Sidereal Time and Local Sidereal Time (GMST/LST) from date-time and longitude, and optional hour.
• Significant Figures & Scientific Notation (with steps).
  Count significant digits, normalize to scientific notation, and compare textbook vs final rounding for + − × ÷.
• Simple harmonic motion (SHM) calculator.
  Compute SHM period, angular frequency, speed, acceleration, and energy for mass-spring and small-angle pendulum.
• Simple Harmonic Motion Simulator.
  Simulate SHM with analytic, Euler-Cromer, or RK4 methods and review period, energy, and plots.
• Simple indicator of liquefaction.
  Typical factors that affect liquefaction during earthquakes (intensity of shaking, shallowness of groundwater level.
• Slope and Grade Calculator (%・°・‰).
  Calculates slope (%/‰), slope angle (°), and slope distance from horizontal distance and elevation difference.
• Snell's law Refraction Calculator.
  Calculate refraction angle, critical angle, and total internal reflection with Snell's law steps.
• Solar altitude/azimuth/sunrise/sunset/day length.
  Approximate solar altitude, solar direction, sunrise/sunset, day length, and solar meridian from latitude/longitude.
• Solubility product (Ksp) & precipitation.
  Relate Ksp, molar solubility and ion concentrations, test Q vs Ksp for precipitation, and explore simple fractional.
• Solution preparation recipes.
  Generate lab-ready recipes from solid reagents or stock solutions and design serial dilution series with steps.
• Standing Waves Frequency Calculator.
  List standing-wave mode frequencies and wavelengths for strings and air columns from basic inputs.
• Stoichiometry & limiting reactant.
  Compute the limiting reactant, theoretical yield, remaining amounts, and percent yield from a balanced chemical.

T

• Target yield back-calculator.
  Back-calculate base and reagent amounts from a target product mass with auto-balanced reactions.
• Thermodynamic process & PV diagram calculator.
  Compute work, ΔU, and heat for ideal-gas isothermal, isobaric, isochoric, adiabatic, and polytropic processes.
• Tide/moon phase/sunrise/sunset calc.
  From the location and date, sunrise, sunset, day length, moon phase (approximate moon phase and illuminance), and tide.
• Tsunami Speed & Arrival Time Calculator.
  Calculate approximate tsunami wave speed and arrival time from average water depth and distance using.
• Twilight, sunrise & sunset calculator.
  Compute sunrise/sunset, civil/nautical/astronomical twilight, and dark-night duration for your location.

U

• USLE/RUSLE Soil erosion (simple calc).
  Simple calculation of soil runoff using the multiplication model A=R×K×LS×C×P of USLE/RUSLE.

V

• Voltage divider & LC resonance calculator – gain.
  Design DC voltage dividers with loading and reverse solves, and compute LC resonance, reactance, Q and bandwidth.

W

• Work, energy & power calculator.
  Compute work, kinetic and potential energy change, and average power from force, distance, mass, speed, and height.

#

• ΔCt / ΔΔCt calculator (relative expression).
  Paste qPCR Ct values to calculate ΔCt/ΔΔCt, log2FC, and fold change.