OpenCalcy
Fast, accurate free online calculators — money, health, math, DIY & developer tools
Mortgage, EMI, BMI, SIP, GST, percentages, age, and 200+ tools — organized by what you’re actually trying to do.
Money
Loans, investing, US & India tax tools, and business math.
Loans & Mortgages
Mortgage, personal loans, auto loans, refinance, amortization, and payoff tools.
31 calculators →
Investing & Savings
Compound interest, SIP-style growth, retirement, ROI, bonds, and savings projections.
36 calculators →
Income & Tax
Salary, take-home pay, income tax, sales tax, VAT, budget, and paycheck tools.
12 calculators →
US Finance
US federal income tax, 401(k), IRA, Roth, Social Security, FHA, VA, HELOC, and sales tax.
12 calculators →
India Finance
GST, SIP, FD, RD, EMI, gratuity, and other India-focused money calculators.
7 calculators →
Business
Margin, break-even, markup, depreciation, IRR, commission, and business loan tools.
11 calculators →
Health
Body metrics, nutrition, fitness, and pregnancy tools.
Body & Health
BMI, body fat, ideal weight, blood pressure, water intake, height prediction, and more.
16 calculators →
Fitness & Nutrition
Calories, TDEE, macros, protein, pace, one-rep max, and training zone calculators.
16 calculators →
Pregnancy & Cycle
Due date, ovulation, fertile window, pregnancy week tracker, and related tools.
9 calculators →
Learn & Build
Math, science, and developer utilities.
Math & Statistics
Percentages, fractions, algebra, geometry, statistics, probability, and scientific tools.
46 calculators →
Science & Engineering
Ohm’s law, electricity, density, molarity, horsepower, wind chill, and lab helpers.
16 calculators →
Developer Tools
Unix timestamp, UUID, hash, regex, JWT peek, Base64, cron, HTTP status, and more.
13 calculators →
Daily Life
Dates, converters, home projects, and everyday helpers.
Date & Time
Age, date difference, workdays, countdown, time zones, and sleep schedules.
14 calculators →
Everyday Life
Tip, bill split, GPA, grades, and practical utilities for school and daily life.
15 calculators →
Converters
Length, weight, temperature, color, file size, Roman numerals, and unit conversions.
15 calculators →
Home & DIY
Concrete, paint-area, roofing, tile, mulch, stairs, fuel cost, and project estimators.
13 calculators →
Popular calculators
Most used tools, ready in one click.
- Mortgage Calculator Estimate monthly mortgage payments, total interest, and amortization summary.
- Scientific Calculator Scientific keypad with trigonometry, logarithms, roots, and powers.
- BMI Calculator Body Mass Index from height and weight with category.
- Percentage Calculator What is X% of Y, X is what % of Y, percent change, and more.
- Calorie Calculator Daily calorie needs using Mifflin–St Jeor (BMR → TDEE).
- Loan Calculator Calculate payment, total cost, or loan amount for personal and installment loans.
- Age Calculator Exact age in years, months, and days from date of birth.
- EMI Calculator Calculate Equated Monthly Installment (EMI) for home, car, personal, or other loans — monthly payment, total interest, and total cost.
- Compound Interest Calculator Detailed compound interest with contribution frequency.
- Income Tax Calculator Estimate US federal income tax (simplified brackets) for single or married filing.
- Height Calculator Predict a child’s adult height from age, weight, and parents’ heights (Khamis–Roche), or use parents-only mid-parental height. Includes a height unit converter.
- Interest Calculator Simple or compound interest growth over time.
Why OpenCalcy?
- Clear categories Find loans, GST, BMI, or regex tools without digging through “Other”.
- Shareable results Copy a link with your inputs baked in.
- Private by default Favorites stay in your browser — no account.