Formula first
See the relationship behind the result and the units it expects.
Free tools. Clear methods. No account.
The calculator library for real-world decisions.
From monthly payments and material estimates to statistics and developer utilities—get reliable answers with formulas you can inspect.
110+working tools
13specialist categories
0sign-ups required
Calculator directory
View complete index →Browse by category
Purpose-built tools organized around the work you need to finish.
18 calculators
Finance
Borrowing, saving, investing, tax, retirement, and debt planning.
Explore finance →5 calculators
Construction & DIY
Material estimates for practical building and renovation projects.
Explore construction →5 calculators
Education & Statistics
Grades, descriptive statistics, and analytical study tools.
Explore education →11 calculators
Health
Everyday health estimates with responsible limitations.
Explore health →5 calculators
Science & Engineering
Common physical and electrical relationships made approachable.
Explore science →4 utilities
Developer Utilities
Networking, encoding, and security helpers that run locally.
Explore developer tools →10 calculators
Math
Fast arithmetic, algebra, probability, and number tools.
Explore math →14 converters
Unit Conversion
Convert everyday and technical units with consistent factors.
Explore conversions →4 calculators
Localized Pay & Tax
Take-home estimates using rates appropriate to your situation.
Explore localized tools →11 calculators
Time & Date
Durations, dates, ages, working days, and time planning.
Explore time tools →6 calculators
Business & Marketing
Commercial metrics for campaigns, pricing, and performance.
Explore business tools →5 calculators
Lifestyle & Planning
Helpful planning tools for milestones and everyday routines.
Explore lifestyle →5 tools
Relationship Tools
Lighthearted compatibility and social calculators.
Explore relationship tools →Frequently used
Popular calculators
Start with the tools people reach for most often.
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Finance
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+Mortgage Calculator
Estimate monthly principal and interest.
Health
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$BMI Calculator
Calculate body mass index by height and weight.
Finance
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%Auto Loan Calculator
Model payments, APR, tax, and trade-in value.
Math
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⌂Percentage Calculator
Find a percentage of any amount instantly.
Construction
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AConcrete Calculator
Estimate cubic yards and bag quantities.
Education
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GPA Calculator
Calculate credit-weighted grade point average.
More than an answer box
Understand the result—not just the number.
Each new TrueCalco tool is designed to show the method, explain the assumptions, and help you decide when an estimate needs professional confirmation.
Read calculator guides →Worked examples
Compare your inputs with a practical example before relying on the output.
Clear limitations
Know which local rules, fees, standards, or assumptions are outside the estimate.
Useful references
Continue to official or authoritative sources when the decision matters.
Recently expanded
34 new calculators across seven practical areas.
Explore the latest tools for building projects, finance, statistics, engineering, development, conversions, and localized pay estimates.