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Finance, health, math, science, unit conversion, business, food, sports, education, and daily planning. Every calculator includes the tool, formula notes, examples, FAQs, and related guides.
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Five calculator collections
Every calculator is organised into one of five topic areas. Click a collection to browse all the tools, sub-categories, and guides it contains.
Finance
137 calculatorsLoans, mortgages, savings, investments, tax, budgets, retirement planning and more.
Health & Fitness
385 calculatorsBMI, calories, nutrition, body composition, fitness training, sports and wellbeing.
Science & Engineering
755 calculatorsPhysics, chemistry, construction, unit conversion, technology and technical design.
Business & Data
252 calculatorsProfit margins, ROI, pricing, statistics, payroll, revenue and business planning.
Everyday Life
491 calculatorsMath, dates, discounts, tips, education, ecology and everyday household decisions.
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Search 2000+ calculators
Type any topic — finance, health, math, construction, sports — and results appear instantly below.
Loan Payment Calculator
Free Loan Payment Calculator: calculate loan payment instantly with transparent formula, worked examples and tips. No signup.
Open calculator FinanceTravel Insurance Calculator
Free Travel Insurance Calculator: calculate travel insurance instantly with transparent formula, worked examples and tips. No signup.
Open calculator HealthProtein Per Kg Calculator
Protein Per Kg Calculator — evidence-based tool to check your protein per kg. Includes formula, tips, and interpretation guide.
Open calculator HealthPain Relief Dose Calculator
Pain Relief Dose Calculator — evidence-based tool to check your pain relief dose. Includes formula, tips, and interpretation guide.
Open calculator MathBisection Method Calculator
Bisection Method Calculator: solve bisection method problems step-by-step. Clear formula, worked example, and FAQs included.
Open calculator ConstructionTrench Volume Calculator
Trench Volume Calculator — estimate trench volume for your project. Fast, accurate, free. No signup required.
Open calculator ConstructionIrrigation Area Calculator
Irrigation Area Calculator — estimate irrigation area for your project. Fast, accurate, free. No signup required.
Open calculator ConversionMolarity to Normality Calculator
Molarity to Normality Calculator: convert molarity to normality instantly. Full formula, unit table, and worked example.
Open calculator PhysicsElectric Potential Calculator
Electric Potential Calculator — calculate electric potential with the correct physics formula. Worked example and unit notes included.
Open calculator PhysicsHawking Radiation Calculator
Hawking Radiation Calculator — calculate hawking radiation with the correct physics formula. Worked example and unit notes included.
Open calculator ChemistryChromatography Rf Calculator
Chromatography Rf Calculator — calculate chromatography rf using standard chemistry formulas. Worked example with units.
Open calculator StatisticsRisk Ratio Calculator
Risk Ratio Calculator: run risk ratio calculations online. Formula, assumptions, and interpretation guide.
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Calculator categories
Each category page works like a focused mini-library with topic clusters, descriptions, internal links, and calculator pages targeting specific search intent.
Finance
Plan loans, savings, investments, taxes, budgets, interest, and everyday money decisions with clear formulas and examples.
137 calculatorsHealth
Estimate health, fitness, nutrition, body measurements, and wellness metrics using practical reference formulas.
135 calculatorsMath
Solve percentages, ratios, fractions, averages, geometry, algebra helpers, and common school or workplace math problems.
131 calculatorsConstruction
Estimate materials, areas, volumes, costs, paint, concrete, flooring, roofing, and renovation quantities.
130 calculatorsConversion
Convert units for length, weight, temperature, speed, volume, area, pressure, energy, and daily measurements.
125 calculatorsPhysics
Work with speed, force, energy, motion, electricity, waves, pressure, and classroom science formulas.
125 calculatorsChemistry
Use chemistry helpers for concentration, molarity, dilution, gas laws, molecular mass, and lab calculations.
125 calculatorsStatistics
Analyze averages, probability, samples, confidence, variation, scores, and data interpretation problems.
125 calculatorsBusiness
Estimate profit, margins, markup, inventory, payroll, pricing, revenue, productivity, and business planning metrics.
127 calculatorsEveryday Life
Quick calculators for dates, time, tips, discounts, travel, fuel, recipes, shopping, and household planning.
110 calculatorsSports
Calculate pace, performance, training zones, scores, ratios, sports statistics, and fitness planning numbers.
125 calculatorsFood
Scale recipes, estimate calories, cooking conversions, ingredient weights, nutrition, and meal planning quantities.
125 calculatorsEcology
Estimate energy use, water use, carbon footprint, recycling, transport impact, and sustainable living metrics.
125 calculatorsEngineering
Work through mechanical, electrical, civil, and systems engineering formulas for practical design checks.
125 calculatorsEducation
Support learning with grade, score, GPA, reading, study time, classroom math, and academic planning calculators.
125 calculatorsTechnology
Estimate bandwidth, storage, download time, screen sizes, data transfer, battery life, and computing metrics.
125 calculatorsAccuracy and transparency
Why United Calculator
Every page follows the same content standard: formula derivation, a worked example with real numbers, applicable laws or professional guidance, 6 plain-language FAQs, and links to 8 related tools.
Verified formulas
Each formula engine is based on published standards — TILA for loan calculations, METS tables for energy expenditure, ASTM standards for materials, and equivalents across 16 subject areas. The formula is shown in a code block on every result card so you can verify the calculation independently.
Professional context, not professional advice
Finance and health calculators cover applicable legislation (CFPB, NHS, OSHA) and reference professional thresholds (e.g. debt-to-income ratios accepted by lenders, WHO BMI categories). Every page includes a disclaimer — these tools are planning aids. Consequential decisions should be reviewed with a qualified professional.
No account, no tracking, no fee
Calculations run entirely in your browser. No data leaves your device. There are no login walls, no usage limits, no subscription tiers, and no premium paywalls. The only data stored is nothing — no cookies are set beyond what your browser requires to render the page.
Transparent methodology
Smart defaults come from published benchmarks — median UK household income from ONS, US average mortgage rate from Freddie Mac weekly surveys, average commute distances from the US Census ACS. Defaults are documented in the article body on each calculator page.
Simple by design
How United Calculator works
Three steps from question to answer — no account, no subscription, no ads cluttering the result.
Search or browse
Type a topic into the search box or click a category. Each category is a mini-library of 125 calculator pages targeting specific questions — loan payments, BMI, tile counts, carbon footprint, and more.
Enter your values
Smart defaults are pre-filled so you get an immediate example result. Replace any field with your own data. Click the ? icon on any field for a plain-language explanation of what that input means.
Read, copy, and share
The result updates in real time. The formula is shown in a code block below the answer. Copy the result to your clipboard, share it to 8 social platforms, or scroll down for the full explanation, FAQs, and 8 related calculators.