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.
• AQI (Air Quality Index) Calculator (US EPA)
  Convert 24-hour PM2.5 and PM10 concentrations (µg/m³) to US EPA AQI.
• Assay standard curves guide
  Use this guide to choose blank handling, fit models, range checks, and reporting details for protein assay and ELISA.
• 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, and equipment settings while opening connected.

B

• Beer-Lambert law & calibration curve
  Compute absorbance, concentration, molar absorptivity, path length, and calibration curves with Beer-Lambert steps.
• Beer-Lambert law guide
  Learn when to use the Beer-Lambert law, how to read calibration curves, when to force the fit through the origin.
• 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

• Calorimetry calculator (specific heat, heat, final temperature)
  Calculate heat, specific heat, temperature change, and final equilibrium temperature for two-substance calorimetry.
• Catalog Resolver Pro
  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
  Calculate required cell suspension and media volume from target cells/well (or cells/cm²), number of wells, volume.
• Centrifuge converter (rpm ↔ RCF ×g)
  Convert between centrifuge speed (rpm) and relative centrifugal force (RCF, ×g) using rotor radius (mm/cm/in).
• CFU/mL Calculator
  Calculate colony forming units per mL from colony count, serial dilution, and plated volume.
• Chemical Equation Balancer + Stoichiometry
  Balance reactions with Gauss-Jordan steps, then compute limiting reagent, percent yield, and redox combinations.
• 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.
• 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

• Depth of Field Calculator
  Estimate focus near limit, far limit, total depth of field, and hyperfocal distance from lens settings.
• Dew Point, Wet Bulb, Heat Index & Wind Chill Calculator
  Calculate dew point, wet bulb temperature, heat index, wind chill, and apparent temperature from temperature.
• Dimensional analysis & unit consistency checker
  Check unit consistency, parse compound units, and build Buckingham Pi groups with step logs and shareable results.
• Distance and bearing calculator for two latitude/longitude
  Calculate distance, initial bearing, and final bearing between two latitude/longitude points with WGS84 ellipsoid.
• Distance Modulus Calculator with Steps (m, M, d)
  Solve the distance modulus formula m - M = 5 log10(d/10 pc) with apparent magnitude, absolute magnitude, or distance.
• 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 dissolved oxygen (DO) saturation and % saturation from water temperature, salinity, and pressure, plus BOD.

E

• Earth Curvature and Horizon Calculator
  Calculate horizon distance, earth curvature drop, hidden height, and how far you can see from observer height.
• 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 stack height calculator (simple plume rise)
  Estimate plume rise Δh and effective stack height He with a simplified Briggs method.
• Electricity CO₂ emissions calc (kWh→kg-CO₂ conversion)
  Estimate electricity-related CO₂ emissions from energy use and an emission factor, with conversion between kg.
• 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
  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.
• Gear Ratio Calculator
  Calculate bicycle gear ratio, gear inches, development, speed from cadence, and simple gear-pair RPM and torque.
• Genetic drift simulator (Wright–Fisher)
  Simulate genetic drift with the Wright–Fisher model.
• Geothermal Gradient and Heat Flow Calculator
  Calculate geothermal gradient and conductive heat flow from two depth-temperature points or a known gradient.
• 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 / χ²)
  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.

I

• IC50/EC50 calculator (4PL/5PL curve fit)
  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
  Fit binding data with one-site or Hill models to estimate Kd.
• Kepler's Third Law Calculator
  Use Kepler's third law (T² = a³/μ) 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
  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

• Manual tide event planner with moon phase and sunrise/sunset
  Review sunrise, sunset, day length, moon phase, illumination, and manually entered tide events for one location.
• 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)
  Estimate Km and Vmax by nonlinear fitting of the Michaelis–Menten equation from substrate [S] and initial rate v.
• MOI Calculator
  Calculate MOI from cell count, infectious titer, and inoculum volume.
• Molar mass / molecular weight
  Calculate molar mass from a chemical formula with element counts, mass percent composition, and grams-to-moles.
• Moment Magnitude (Mw) Calculator from Seismic Moment M0
  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)
  Convert NGS library concentration from ng/µL and fragment length to nM, then calculate normalization dilutions.
• Noise dB Calculator (Addition and Distance Attenuation)
  Add sound levels in decibels, estimate free-field distance attenuation, and back-calculate the distance needed.
• 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 Flow Calculator (Manning Equation)
  Estimate open-channel velocity and discharge with the Manning equation for rectangular, trapezoidal, and circular.

P

• P-wave / S-wave epicenter distance calculator
  Estimate epicenter distance from the P-wave and S-wave arrival gap (S-P) and back-calculate the event time.
• 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
  Calculate PCR/qPCR master mix volumes from reaction count, stock/final concentrations, overage, well format.
• PCR Primer Tm Calculator
  Calculate primer Tm and PCR annealing temperature 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)
  Convert gas ppm or ppb to mg/m³ and back using molecular weight, temperature, and pressure.
• Pressure Altitude Calculator
  Calculate pressure altitude, altitude from pressure, or sea-level pressure from a local reading with standard.
• 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
  Analyze 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 Calculator
  Calculate Greenwich mean sidereal time (GMST), local sidereal time (LST), and optional hour angle from date-time.
• 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
  Visualize shaking, groundwater, and soil factors with a simple educational liquefaction score.
• Slope Grade Calculator
  Calculate slope grade, angle, rise, run, and slope distance from rise over run or from two elevations.
• Snell's law Refraction Calculator
  Calculate refraction angle, critical angle, and total internal reflection with Snell's law steps.
• Solubility product (Ksp) & precipitation
  Compare Ksp, Q, and molar solubility to test precipitation and simple fractional ranges.
• 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.
• Sun Position Calculator: Solar Noon, Altitude & Azimuth
  Calculate solar noon, solar altitude, azimuth, sunrise, sunset, and day length from latitude/longitude, date.

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.
• Torque, RPM & Power Calculator
  Calculate torque, RPM, horsepower, or kilowatts from the other two values.
• 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)
  Estimate soil erosion loss with the USLE/RUSLE model A=R×K×LS×C×P.

V

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