Free Online Calculators

Free Online Calculators That Actually Work

ToolRux offers 31 free online calculators built for speed and accuracy. Whether you need to plan a mortgage, project retirement savings, check inflation impact, estimate fuel costs, or calculate your GPA, you'll get instant, reliable results.

Financial Calculators

Make smarter money decisions with our suite of financial calculators, all supporting 20+ world currencies with automatic locale detection:

• Mortgage Calculator — Calculate monthly home payments with property tax, insurance, PMI, and a full yearly amortization schedule.
• Retirement Calculator — Project your retirement corpus, safe withdrawal income via the 4% rule, and year-by-year growth with inflation adjustment.
• Savings Goal Calculator — Find the exact monthly savings needed to reach any financial target, factoring in compound interest.
• Inflation Calculator — See how inflation erodes purchasing power. Look back in time or project forward with custom rates.
• Compound Interest Calculator — Visualize how your savings or investments grow with daily, monthly, quarterly, or annual compounding.
• SIP Calculator — Estimate your mutual fund systematic investment plan returns with monthly compounding.
• Step-up SIP Calculator — Model how increasing your SIP contribution by a fixed percentage each year accelerates wealth creation.
• Loan EMI Calculator — Calculate monthly EMI payments, total interest payable, and see a full amortization schedule.
• Invoice Tax Calculator — Add or remove GST, VAT, or sales tax from any price. Reverse tax calculation with quantity support.
• Discount Calculator — Calculate sale prices, stacked discounts, and final cost after tax.
• Tip Calculator — Split bills, calculate custom tip percentages, and see per-person totals instantly.
• Salary Calculator — Convert salary between time periods with multi-country tax estimates for 15 countries.
• ROI Calculator — Calculate return on investment, annualized ROI, and compare multiple investment scenarios side by side.
• Margin & Markup Calculator — Convert between profit margin and markup percentage, and calculate cost, revenue, and profit.
• CAGR Calculator — Calculate compound annual growth rate from an initial and final value over any time period.
• Paycheck Calculator — Estimate your take-home pay after federal and state taxes, deductions, and withholdings.
• Rent Affordability Calculator — Find out how much rent you can afford based on your income, expenses, and the 30% rule.

Health & Fitness Calculators

Track your health metrics with evidence-based calculators:

• BMI Calculator — Calculate your Body Mass Index using height and weight in metric or imperial units. Understand your WHO weight category and healthy weight range.
• Calorie Calculator — Find your Total Daily Energy Expenditure (TDEE) and recommended calorie intake based on the Mifflin-St Jeor equation, activity level, and fitness goals (lose, maintain, or gain weight).
• Body Fat Calculator — Estimate your body fat percentage using the Navy tape-measure method with simple measurements — no calipers needed.
• TDEE Calculator — Calculate your Total Daily Energy Expenditure based on your basal metabolic rate and activity level for precise nutrition planning.
• Pregnancy Due Date Calculator — Estimate your due date based on your last menstrual period or conception date, with trimester timeline and milestone tracking.
• Sleep Calculator — Find the best times to go to bed or wake up based on 90-minute sleep cycles to feel refreshed and energized.

Education & Academic Calculators

• GPA / CGPA Calculator — Calculate semester GPA (SGPA) and cumulative GPA (CGPA) across 5 global grading systems: 4.0 scale, CBCS 10-point, degree classification (First / 2:1 / 2:2 / Third), 1–5 scale, and HD–F system. Includes cross-system grade equivalents.
• Scientific Calculator — Perform advanced math operations including trigonometric functions (sin, cos, tan), logarithms (log, ln), exponents, square roots, factorials, constants (π, e), and parenthesized expressions.

Everyday Calculators

• Percentage Calculator — Quickly find percentages, percentage change, percentage increase/decrease, and "what percent of" calculations.
• Age Calculator — Calculate your exact age in years, months, and days from your date of birth. Also shows how many days remain until your next birthday.
• Date Difference Calculator — Find the precise number of days, weeks, months, and years between any two dates.
• Fuel Cost Calculator — Estimate trip fuel costs with km/L, L/100km, or MPG efficiency, passenger splitting, and CO₂ estimates.
• Electricity Cost Calculator — Estimate your power bill by adding appliances with wattage and daily usage. See per-appliance breakdown.
• Love Calculator — A fun compatibility calculator that generates a love score between name pairs. Great for entertainment!

Looking for unit, currency, or time zone conversions? Check out our Converter Tools.

Why Use ToolRux Calculators?

• Free to Use — Use every calculator instantly.
• Accurate — Industry-standard formulas and reliable calculation methods.
• Multi-Currency Support — Financial calculators auto-detect your locale and support 20+ currencies including USD, EUR, GBP, INR, JPY, AUD, CAD, and more.
• Mobile Friendly — Fully responsive design works perfectly on phones, tablets, and desktops.
• Dark Mode — Easy on the eyes with automatic dark mode support.
• Fast & Lightweight — Built with modern web technology for instant load times and smooth interactions.

Frequently Asked Questions

Are these calculators really free?

Yes — every calculator on ToolRux is free to use.

Is my data safe?

ToolRux takes data safety seriously. Please see our privacy policy for details on how we handle your data.

Can I use these calculators on my phone?

Yes. All calculators are fully responsive and work on any modern browser — Chrome, Safari, Firefox, Edge — on mobile phones, tablets, and desktop computers.

What formula does the BMI calculator use?

The BMI calculator uses the standard World Health Organization formula: BMI = weight (kg) ÷ height² (m²). It supports both metric (kg/cm) and imperial (lb/ft-in) input.

How is the calorie calculator's TDEE calculated?

The calorie calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then multiplies it by an activity factor to determine your Total Daily Energy Expenditure (TDEE).

How does the mortgage calculator work?

It uses the standard amortization formula to compute monthly principal & interest, then adds property tax, homeowner's insurance, and PMI (if your down payment is under 20%). You get the true total monthly cost plus a yearly amortization schedule showing how principal and interest shift over time.

What is the 4% rule used in the retirement calculator?

The 4% rule suggests withdrawing 4% of your retirement portfolio in the first year, adjusting for inflation each subsequent year. Based on historical stock and bond returns, this approach has a high probability of sustaining your savings for 30+ years.

How does the inflation calculator work?

It uses compound inflation: adjusted value = amount ÷ (1 + rate)^years. You can look backward ("what was $10,000 worth 20 years ago?") or forward ("what will $10,000 buy in 20 years?"). Preset rates for low (2%), moderate (3.5%), high (6%), and very high (10%) inflation are included.

Can I add or remove tax with the invoice calculator?

Yes. Two modes: "Add Tax" calculates the tax-inclusive price from a base price, and "Remove Tax" extracts the base price and tax amount from a tax-inclusive number. Common rate presets (5%–28%) make GST, VAT, and sales tax calculations one-click.