Math tools

Percent of a number, what-percent, and percentage change — all three.

Add, subtract, multiply, and divide fractions, simplified automatically.

Mean, median, mode, range, variance, and standard deviation from a list.

Simplify a ratio or solve a proportion for the missing value.

Trig, logs, powers, and roots with a clean expression display.

Count significant figures and round a number to any precision.

Convert between binary, octal, decimal, and hexadecimal at once.

Turn course grades and credit hours into a weighted 4.0 GPA.

Weight your assignments to find your current grade and what you still need.

Evaluate algebraic math expressions, formulas, and equations securely in-browser.

Verify if a number is prime and generate lists of prime numbers within ranges.

Convert normal integer numbers to Roman numerals and vice versa.

area, perimeter, circle (circumference/arc/sector), polygon, trapezoid, ellipse, star

right triangle, hypotenuse, Pythagorean theorem, law of sines/cosines, area of triangle, 30-60-90, similar triangles

volume & surface area for sphere/cylinder/cone/pyramid/prism/torus

sin/cos/tan, inverse trig, unit circle, trig identity solver

quadratic equation, system of equations, factoring, polynomial roots, completing the square, synthetic division, slope & slope-intercept, distance for

determinant, inverse, multiply, transpose, rank, eigenvalues

log, antilog, exponent, scientific notation, nth root

add/subtract/multiply/divide, simplify, mixed number ↔ improper, decimal ↔ fraction

LCM, GCF/HCF, factorial, long division, rounding, weighted average, average, absolute change

Fibonacci, arithmetic sequence, geometric sequence, series sum

binary add/subtract/multiply/divide, two's complement, bitwise ops

percent error, percent change, percent difference, percent-off, fraction-to-percent

Mean, Median, Mode & Range Calculator online tool

Five Number Summary / IQR / Quartile / Outlier Detector online tool

Z-Score Calculator + Z-Table online tool

P-value Calculator *(one of Omni's top-16 featured tools)* online tool

Confidence Interval Calculator *(also top-16 featured)* online tool

Margin of Error / Sample Size Calculator online tool

t-test, Chi-Square, ANOVA, F-statistic Calculators online tool

Normal / Binomial / Poisson Distribution Calculators online tool

Linear Regression & Correlation Coefficient (Pearson/Spearman) Calculator online tool

R-squared / Coefficient of Determination Calculator online tool

Probability Calculator (single, joint, conditional, Bayes' theorem) online tool

Permutation & Combination Calculator online tool

Histogram / Box Plot / Pie Chart Maker *(overlaps \"Chart Maker\" in Part 3)* online tool

Ohm's Law, resistor color code, LED resistor, voltage divider, series/parallel resistors & capacitors, wire gauge/size, RC & RLC circuit, 555 timer, r

watts to amps, kVA, voltage drop, power factor, electrical power, watt-hour, battery capacity & life

speed/velocity/acceleration, free fall, projectile motion, force, momentum, friction, stopping distance

kinetic/potential energy, work, efficiency, power-to-weight ratio

ideal gas law, Boyle's/Charles's law, specific heat, heat transfer, thermal expansion, BTU ↔ tons, water heating

Bernoulli, Reynolds number, flow rate, pipe velocity/volume, hydrostatic & water pressure, drag

dew point, relative/absolute humidity, heat index, wind chill, air density, air pressure at altitude

Snell's law, lens/mirror equation, focal length, magnification, index of refraction

decibel, dB gain, speed of sound, wavelength, frequency, Doppler effect

escape velocity, orbital period, light year, E=mc², time dilation, Schwarzschild radius

density, stress/strain, Young's modulus, beam deflection, gear ratio, pulley, spring rate

Molarity, Molality & Normality Calculators online tool

Dilution / Solution Dilution / Serial Dilution Calculator online tool

pH, pOH & Buffer pH (Henderson-Hasselbalch) Calculator online tool

Chemical Equation Balancer *(very high volume, purely algorithmic)* online tool

Percent Yield / Theoretical Yield / Actual Yield Calculator online tool

Mole ↔ Grams ↔ Atoms Converters, Avogadro's Number Calculator online tool

Empirical & Molecular Formula Calculator online tool

Percent Composition & Mass Percent Calculator online tool

Ideal Gas Law / Combined Gas Law Calculator online tool

Half-Life & Radioactive Decay Calculator online tool

Electron Configuration & Atomic Mass Calculator online tool

Boiling/Freezing Point Elevation & Depression, Vapor Pressure online tool

Gibbs Free Energy, Entropy, Enthalpy Calculators online tool

Beer-Lambert Law Calculator online tool

Interactive Periodic Table *(not an Omni tool, but the obvious hub page for this whole cluster)* online tool

concrete, cement, mortar, grout, brick, block, gravel, sand, tile, drywall, lumber, plywood, rebar, decking, insulation

square footage, cubic yard, board foot, square feet ↔ cubic yards

paint, wallpaper, carpet, flooring, paver, fence, deck stain, epoxy, stairs, ramp, ladder angle

AC tonnage, BTU, furnace/boiler size, CFM, air changes per hour, heat loss

roof pitch, rafter length, shingles, roof truss, snow load

asphalt, crushed stone, gravel driveway, road base

pool volume, tank volume, pipe volume, pond, GPM

beam load & deflection, bolt torque, floor joist, wood beam span, thread pitch

Grams ↔ Cups / Tablespoons / Teaspoons Converters *(individual pages; huge volume)* online tool

Butter Stick Converter, Oil ↔ Butter, Yeast Converter, Self-rising Flour online tool

Cake Pan Size Converter & Cake Serving Calculator online tool

Baker's Percentage & Sourdough Calculator online tool

Pizza Size Comparison & Pizza Party Calculator online tool

Coffee-to-Water Ratio / Cold Brew Ratio Calculator online tool

Rice-to-Water Ratio, Dry ↔ Cooked Pasta Converter online tool

Turkey / Ham / Steak Cooking Time & Thawing Calculators *(seasonal spikes)* online tool

ABV (Alcohol by Volume) & Standard Drink Calculator online tool

Party Drink / Wedding Alcohol / BBQ Party Calculator online tool

Egg Boiling Timer, Brine Calculator online tool

Solar Panel Size & Wattage Calculator *(strong commercial intent)* online tool

EV / Plug-in Hybrid Running Cost Calculator *(pairs with `fuel-economy-converter`)* online tool

Wind Turbine Output & Profit Calculator online tool

Tree Benefits / Tap Water vs Bottled Calculator online tool

batting strike rate, bowling average, net run rate, Duckworth-Lewis

bike size, bike gear/cadence, cycling wattage, e-bike range, calories burned biking

marathon pace, race predictor, running splits, steps to km/miles, stride length, training pace

batting average, ERA, OPS, slugging %, true shooting %

VO₂ Max & Max Heart Rate Calculators online tool

Bench Press 1RM / 5-3-1 / Bench Pyramid Calculators online tool

Elo Rating & Winning Percentage Calculators online tool

Punnett Square Calculator (mono/di/trihybrid) *(highest-volume biology term)* online tool

Hardy-Weinberg Equilibrium Calculator online tool

DNA → mRNA / Codon Translator, DNA Concentration Calculator online tool

Cell Doubling Time / Dilution Calculators online tool

plant spacing, soil volume, seed & fertilizer calculators

DD ↔ DMS ↔ UTM, lat/long

fits the existing CSS cluster)*

very high volume)*

Military / Zulu Time Converter *(Luminus has `timezone-converter` but not 24h ↔ 12h military notation)* online tool

Scale Calculator (model/map scale ratios) online tool

Ring Size, Bra Size, Hat Size, Glove Size Converters *(Luminus has shoe & clothing size)* online tool

Hardness Conversion (Rockwell/Brinell/Vickers), Mesh ↔ Micron online tool

Gematria & Leet-speak Translators *(fun tier; sits next to `morse-translator` and `upside-down`)* online tool

fuel cost, gas trip cost, MPG, drive time, horsepower, compression ratio, tire size, wheel offset, 0-60

electricity cost, appliance wattage, generator wattage, LED savings, lumens to watts, cord of wood, unit price

fabric, quilt, curtain size, tablecloth size, circle skirt

moon phase, leap year, day of the year, week number, Korean age, half birthday, anniversary, day-of-week for any date, add/subtract time

meeting cost, words per minute (typing test), reading time & reading speed, deadline, lead time, cycle time

Rug/sofa/bed/TV/desk-size sizing calculators *(pairs with the existing `sizing-monitor`)* online tool

final grade, grade curve, semester grade, ACT/SAT/IELTS score