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Quick answers to everyday money questions
Work out GST on a price, the EMI on a loan, the growth rate of an investment, or produce an invoice in a minute. Below each tool is a worked example, so you know what the numbers mean.
GST: adding it, or taking it out
The GST calculator works both ways. Exclusive adds GST to a price: base × rate. Inclusive takes it out of a total that already includes GST: total − total ÷ (1 + rate). The second is the one people get wrong, by taking the rate off the total directly.
You enter the rate; the calculator doesn't pick one, because the right rate depends on what you're selling.
Worked example, at a 10% rate chosen for easy arithmetic
- Inclusive total
- ₹1,100
- GST = 1,100 − 1,100 ÷ 1.10
- ₹100
- Base price
- ₹1,000
Not 10% of ₹1,100 (₹110), which is the common mistake.
EMI: what a loan costs each month
The EMI calculator uses the standard reducing-balance formula: EMI = P × r × (1 + r)n ÷ ((1 + r)n − 1), where P is the loan, r the monthly rate and n the number of months. Early EMIs are mostly interest; later ones mostly principal.
It shows interest only. Real loans can add processing fees and other charges, which is why a lender's Key Fact Statement and APR are the numbers to compare. More in the working capital guide.
Worked example
- Loan
- ₹1,00,000
- Rate, 12 months
- 12% a year
- Monthly EMI
- ₹8,884.88
- Total repaid
- ₹1,06,618.55
- Total interest
- ₹6,618.55
Hypothetical rate for the arithmetic; not an offer.
CAGR: growth as one steady rate
Compound annual growth rate is (ending value ÷ starting value)1 ÷ years − 1. It answers: what constant yearly rate would have taken me from here to there? Use it to compare growth over different periods, such as revenue across years or two investments held for different lengths of time.
It hides the path: a business that fell and recovered can have the same CAGR as one that grew steadily.
Invoices that get paid
The invoice generator creates a clean invoice with your logo, which you can download. A good invoice gets paid faster: it has a number, a date, a clear description, the amount, the due date, and a way to pay.
If you're GST-registered, your invoices have their own required details; check them with your adviser.
Numbered in sequence
Never reused.
Due date, not 'on receipt'
A date customers can plan around.
How to pay
Bank details with a reference, or a payment link.
Calculator questions
Are the calculators free?
Yes, with no sign-up. The calculators run in your browser; the numbers you enter aren't sent to Peneu.
Which GST rate should I use?
The rate that applies to your goods or services, which depends on what they are. The calculator doesn't choose a rate for you; check the applicable rate with your tax adviser or official GST sources.
Why does my lender's EMI differ from the calculator's?
Lenders may calculate interest daily, charge fees, or start the first instalment on a different date. The calculator uses the standard reducing-balance formula; the lender's Key Fact Statement shows the actual cost, including the APR.
Is CAGR the same as average return?
No. CAGR is the single steady rate that turns the starting value into the ending value over the period. An average of yearly returns can differ from it, especially when returns swing.