⭐ Starlight Tools / Calculators

Calculators

Free browser-based calculators for math, science, units, GPA, electronics, construction, and everyday problems. Everything runs locally in your browser for privacy. Try our GPA Calculator, Unit Converter, Molarity Calculator, or Ohm’s Law Calculator.

Base converter calculator tool for binary, hex, octal, and decimal conversions in-browser

Binary/Hex/Octal Converter

Convert between binary, octal, decimal, and hex instantly. Supports negatives, BigInt, prefixes, and 4-bit grouping — all client-side. v1.0

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GPA calculator tool showing course rows, credits, and weighted GPA totals

GPA Calculator

Calculate your GPA for high school or college, including cumulative and "what do I need" options. v1.0

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Test score converter calculator for SAT to ACT and GRE to GMAT tables

SAT↔ACT Converter & GRE↔GMAT Comparator

Official SAT–ACT concordance with two-way conversion, plus a transparent GRE→GMAT percentile-based estimator (Focus & legacy). Private, client-side. v1.0

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Quadratic equation calculator tool solving ax² + bx + c = 0 with steps

Quadratic Equation Calculator

Solve quadratic equations (ax² + bx + c = 0) and see the step-by-step solution. v1.0

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Ratio calculator tool solving proportional values with visualization

Ratio Calculator

Solve for a missing ratio value and visualize the relationship. v1.0

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Fraction calculator tool adding and simplifying mixed numbers

Fraction Calculator

Add, subtract, multiply, and divide fractions & mixed numbers — with automatic simplification, steps, and decimals. v1.0

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Proportion calculator tool solving a is to b as c is to question mark

Proportion Calculator

Solve proportions step by step — find the missing value in “a is to b as c is to ?”. v1.0

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Mean median mode calculator tool summarizing dataset statistics

Mean, Median, Mode Calculator

Calculate the mean, median, mode, range, and other key statistics for a set of numbers. v1.0

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Standard deviation and z-score calculator tool with data table and graph

Standard Deviation & Z-Score

Paste numbers to get mean, variance, σ (population/sample), and per-value z-scores — 100% client-side and private. v1.0

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Binomial and Poisson probability calculator tool with PMF and CDF chart

Binomial & Poisson Calculator

Enter n,p,k (or λ,k) to get PMF/CDF, expected value, variance, and a clean probability graph — 100% client-side. v1.0

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Average mean calculator tool with list input and result summary

Average (Mean) Calculator

Compute the arithmetic mean instantly. Supports spaces, commas, and new lines, plus adjustable precision — all client-side. v1.0

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Exponent power calculator tool with base and exponent fields

Exponent / Power Calculator (xy)

Enter a base and exponent in a kid-friendly xy layout. Supports negatives, zero exponents, and scientific notation. v1.0

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Prime factorization calculator tool listing prime factors and exponents

Prime Factorization Calculator

Check if a number is prime and see its full prime factorization with exponents — instant, private, and student-friendly. v1.0

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Scientific notation converter calculator tool showing standard to scientific results

Scientific Notation Converter

Convert standard ↔ scientific & engineering notation, with E-notation and significant figures—100% client-side. v1.0

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Logarithm calculator tool computing log base b, ln, log10, and log2

Logarithm Calculator

Compute ln, log10, log2, and log base b with change-of-base and antilog — 100% client-side. v1.0

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Permutation and combination calculator tool for nPr and nCr results

Permutation & Combination Calculator

Compute nPr and nCr — with or without repetition. Exact BigInt results plus scientific approximation. v1.0

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LCM and GCF calculator tool displaying factors and results

LCM & GCF Calculator

Compute least common multiple and greatest common factor for any list of integers — BigInt support, 100% client-side. v1.0

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Molarity calculator tool for solution concentration, mass, and volume

Molarity Calculator

Calculate mass, molecular weight, volume, or concentration for chemical solutions. v1.1

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Dilution calculator tool using C1V1 equals C2V2 for solutions

Dilution Calculator (C1V1=C2V2)

Calculate unknown concentrations or volumes using the C1V1=C2V2 formula. v1.0

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Temperature converter calculator tool for Celsius, Fahrenheit, Kelvin, Rankine and Reaumur

Temperature Converter

Convert between Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur. v1.0

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All-in-one unit converter calculator tool for length, mass, area, volume, speed, time, and storage

All-in-One Unit Converter

Convert length, mass, temperature, area, volume, speed, time, and digital storage — all client-side for privacy. v1.0

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Tire size calculator tool comparing dimensions and speedometer error

Tire Size Calculator

Compare two tire sizes (e.g., 225/45R17 vs 235/40R18) by sidewall, diameter, circumference, revs per mile/km, ride height, and speedometer error. v1.0

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IP subnet calculator tool for IPv4 and IPv6 network ranges and hosts

IP Subnet Calculator

Enter IPv4 or IPv6 CIDR (e.g., 192.168.1.10/24, 2001:db8::/48) to see network, range, and counts — all client-side for privacy. v1.0

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Ohm's Law calculator tool solving voltage, current, resistance and power

Ohm’s Law Calculator

Enter any two values (V, I, R, P) to instantly compute the other two. Includes unit scaling and step-by-step formulas. v1.0

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AC power calculator tool for real, reactive and apparent power single or three phase

AC Power Calculator

Compute real (P), apparent (S), and reactive (Q) power from V, I, and pf/angle — single- or three-phase. Client-side & private. v1.0

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DC power calculator tool showing voltage, current, resistance and power fields

DC Power Calculator

Compute direct current power with P = V × I — enter any two of V, I, R, P and get the rest. School-friendly, client-side, private. v1.0

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Voltage divider calculator tool solving Vin, Vout, R1, R2 with load simulation

Voltage Divider Calculator

Solve any one of Vin, Vout, R1, or R2 from the other three. Includes load simulation, current, and power — all client-side. v1.0

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dB dBm watt converter calculator tool including Vrms Vpp and Irms outputs

dB / dBm / Watt Converter

Convert between dB, dBm, dBW, and Watts — with optional 50 Ω Vrms/Vpp/Irms readouts. 100% client-side. v1.0

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Wavelength to frequency calculator tool using lambda equals c divided by n times f

Wavelength ↔ Frequency Calculator

Convert between wavelength and frequency using λ = c/(n·f). Choose a medium (vacuum, air, water, glass) or enter refractive index. Extras: period, wavenumber, photon energy. 100% client-side. v1.0

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UPS runtime and sizing calculator tool with load, runtime, and battery results

UPS Runtime & Sizing Calculator

Estimate UPS runtime, required battery capacity, and proper kVA sizing from load, voltage, and backup needs. 100% client-side and private. v1.0

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RAID calculator tool estimating usable capacity and redundancy for RAID levels

RAID Calculator

Estimate usable capacity, redundancy overhead, and fault tolerance for RAID 0, 1, 5, 6, 10, 50 & 60 — all client-side. v1.0

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Coverage calculator tool for paint, flooring, and tile with room inputs and totals

Paint, Flooring & Tile Coverage Calculator

Estimate paint, flooring and tile materials for multiple rooms. Coats & waste, metric/imperial, tins/packs/boxes. Private, client-side. v1.0.0

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Packing volume calculator tool listing box types, items, and recommended box counts

Packing Volume Calculator

Plan moving or shipping boxes in seconds. Add items and box types, set packing efficiency and fragile padding, and get recommended box counts with volumes and weights. v1.0.0

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Fabric yardage calculator tool for sewing projects with width allowances and repeats

Fabric Yardage Calculator

Estimate fabric for sewing—curtains, clothing, cushions & more. Accounts for fabric width, allowances, nap/directional prints, repeats, shrinkage, and store rounding. 100% client-side. v1.0.0

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Concrete yardage calculator tool computing yards and bag counts for slabs footings and holes

Concrete Yardage Calculator

Estimate concrete for slabs, footings and post holes. Imperial/metric, waste %, and bag counts. 100% client-side. v1.0.0

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HVAC BTU calculator tool estimating cooling, heating BTU and AC tonnage from room details

HVAC BTU Calculator

Estimate cooling & heating BTU/h, convert to AC tonnage, and add headroom with friendly adjustments. v1.0.0

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About These Calculator Tools

Starlight Tools offers a privacy-first collection of calculators for math, science, electronics, construction, and everyday conversions. Every calculation runs in your browser—no logins, no uploads, and no data leaves your device.

Popular picks include the GPA Calculator, Unit Converter, Molarity Calculator, Ohm’s Law Calculator, and RAID Calculator. Use them free, anytime, on any device.