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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 calculators

Loans, mortgages, savings, investments, tax, budgets, retirement planning and more.

Finance
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Health & Fitness

385 calculators

BMI, calories, nutrition, body composition, fitness training, sports and wellbeing.

HealthSportsFood
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Science & Engineering

755 calculators

Physics, chemistry, construction, unit conversion, technology and technical design.

ConstructionConversionPhysicsChemistryEngineeringTechnology
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Business & Data

252 calculators

Profit margins, ROI, pricing, statistics, payroll, revenue and business planning.

StatisticsBusiness
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Everyday Life

491 calculators

Math, dates, discounts, tips, education, ecology and everyday household decisions.

MathEveryday LifeEcologyEducation
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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 calculators

Health

Estimate health, fitness, nutrition, body measurements, and wellness metrics using practical reference formulas.

135 calculators

Math

Solve percentages, ratios, fractions, averages, geometry, algebra helpers, and common school or workplace math problems.

131 calculators

Construction

Estimate materials, areas, volumes, costs, paint, concrete, flooring, roofing, and renovation quantities.

130 calculators

Conversion

Convert units for length, weight, temperature, speed, volume, area, pressure, energy, and daily measurements.

125 calculators

Physics

Work with speed, force, energy, motion, electricity, waves, pressure, and classroom science formulas.

125 calculators

Chemistry

Use chemistry helpers for concentration, molarity, dilution, gas laws, molecular mass, and lab calculations.

125 calculators

Statistics

Analyze averages, probability, samples, confidence, variation, scores, and data interpretation problems.

125 calculators

Business

Estimate profit, margins, markup, inventory, payroll, pricing, revenue, productivity, and business planning metrics.

127 calculators

Everyday Life

Quick calculators for dates, time, tips, discounts, travel, fuel, recipes, shopping, and household planning.

110 calculators

Sports

Calculate pace, performance, training zones, scores, ratios, sports statistics, and fitness planning numbers.

125 calculators

Food

Scale recipes, estimate calories, cooking conversions, ingredient weights, nutrition, and meal planning quantities.

125 calculators

Ecology

Estimate energy use, water use, carbon footprint, recycling, transport impact, and sustainable living metrics.

125 calculators

Engineering

Work through mechanical, electrical, civil, and systems engineering formulas for practical design checks.

125 calculators

Education

Support learning with grade, score, GPA, reading, study time, classroom math, and academic planning calculators.

125 calculators

Technology

Estimate bandwidth, storage, download time, screen sizes, data transfer, battery life, and computing metrics.

125 calculators

Accuracy 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.

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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.

Brownie Squares Calculator

Brownie Squares Calculator: calculate brownie squares for cooking and nutrition. Practical tips and worked examples.

A recipe scale calculator multiplies or divides all ingredient quantities in a recipe by a scaling factor, so you can cook for any number of servings without manual arithmetic. It divides your target serving count by the original serving count to produce a scaling factor, then applies that factor to every ingredient. Scaling sounds simple, but several cooking variables — leavening agents, cooking time, and temperature — do not scale linearly and require separate adjustments. and provide complementary tools for nutritional and cooking-time calculations.

Recipe scaling is essential for catering, batch cooking, meal prep, and adapting recipes designed for different serving sizes. A recipe written for 4 that you need to serve to 25 requires a scaling factor of 6.25 — straightforward for flour and water, but leavening agents such as baking powder and baking soda should only be scaled by approximately 75% of the factor to avoid a bitter aftertaste or over-rising. Similarly, cooking times increase for larger volumes but not proportionally — they scale roughly with the square root of the volume ratio.

  1. Enter the original number of servings the recipe is written for.
  2. Enter the number of servings you want to make.
  3. The calculator computes the scaling factor: new servings ÷ original servings.
  4. Enter your key ingredient quantities — the calculator multiplies each by the factor.
  5. Apply the scaling factor to all ingredients except leavening agents (use 75% of factor for baking powder, baking soda, yeast).
  6. Adjust cooking time separately — do not scale it directly; use a cooking time calculator or check internal temperature.

Recipe scaling formula

Scaling factor = New servings ÷ Original servings

Scaled ingredient = Original quantity × Scaling factor

Leavening adjustment = Original leavening × (Scaling factor × 0.75)

Worked example: Recipe serves 4, you need 10. Scaling factor = 10 ÷ 4 = 2.5. Flour 200g → 500g. Baking powder 8g → 8 × (2.5 × 0.75) = 15g (not 20g). Note: temperature does NOT scale — always keep the oven at the same temperature as the original recipe.

What does not scale linearly?

Scaling rules by ingredient type

Most ingredients scale directly with the factor. Exceptions: leavening agents (baking powder, baking soda, yeast) — use 75% of the scaling factor; salt and strong spices — scale by 50–75% and adjust to taste; cooking time — increases, but not proportionally; for doubled volume, add approximately 25–35% more time and check core temperature; oven temperature — never scale; keep the same temperature as the original recipe regardless of batch size.

Food tips and best practices

Common mistakes to avoid

Recipe scaling calculations are guides based on culinary conventions. Food safety requirements — particularly internal temperature minimums for meat, poultry, and egg dishes — are set by the USDA FSIS and must always be met regardless of recipe scaling. Commercial food production is subject to food hygiene regulations. Allergen labeling requirements apply to any food produced for sale. This calculator is for home cooking and planning purposes only.