Finance Tools
7 free tools — precise calculations, instant results.
loan calculator
Launch tool
gst vat tax
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percentage
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tip calculator
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compound interest
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roi calculator
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salary hourly
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About Finance Tools
Finance calculators help you calculate loan EMIs, compound interest, ROI, GST/VAT, tips, and salary conversions. All calculations use transparent formulas based on standard financial mathematics.
Understanding Loan EMI Calculations
EMI (Equated Monthly Installment) is the fixed monthly payment on an amortizing loan. It is calculated using the formula: EMI = P × r × (1+r)^n / ((1+r)^n − 1), where P is principal, r is the monthly interest rate (annual rate ÷ 12 ÷ 100), and n is the loan term in months. Early in the loan, most of your EMI goes toward interest. As you pay down principal, the interest portion decreases while the principal portion increases—this is called amortization.
Compound Interest vs Simple Interest
Simple interest is calculated only on the principal: Interest = P × r × t. Compound interest is calculated on the principal plus accumulated interest: A = P(1 + r/n)^(nt). Over long periods, compound interest grows exponentially—this is why starting investments early is so powerful and why carrying credit card debt is so costly.
GST, VAT, and Sales Tax Explained
GST (Goods and Services Tax) and VAT (Value Added Tax) are consumption taxes applied at each stage of the supply chain. To calculate the tax-inclusive price: Price × (1 + Rate/100). To extract the pre-tax price from a tax-inclusive amount: Total ÷ (1 + Rate/100). Tax rates vary by country: India GST ranges from 0–28%, UK VAT is 20%, and EU VAT varies from 17–27%.
Frequently Asked Questions
What is the difference between APR and interest rate?
The interest rate is the base cost of borrowing the principal. APR (Annual Percentage Rate) includes the interest rate plus fees and other costs, giving a more complete picture of the true cost of a loan.
How do I calculate ROI?
ROI = (Net Profit ÷ Cost of Investment) × 100. For example, if you invest $1,000 and gain $1,200, your ROI is ((1200−1000) ÷ 1000) × 100 = 20%.
What is the rule of 72?
The rule of 72 is a shortcut to estimate how long it takes an investment to double: Years to double = 72 ÷ Annual Interest Rate. At 6% annual return, your money doubles in approximately 12 years.