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Interest Calculator — Simple, Compound & Penal Interest

Work out simple or compound interest on an overdue sum — useful for money-recovery notices, penal-interest claims on delayed payments, or any interest computation between two dates. Enter the principal, the annual rate and the period to get the interest and total payable.

Period: 202 day(s)
Interest amount
₹33,205.48
Total payable (principal + interest)
₹5,33,205.48

Simple interest over 202 day(s) at 12% per annum.

How this is calculated

The period is the number of calendar days between the "from" and "to" dates, converted to years by dividing by 365.

  • Simple interest: Interest = Principal × Rate × Time (in years), i.e. I = P × r × t.
  • Compound interest: the interest is compounded at the chosen frequency (monthly / quarterly / annually) using A = P × (1 + r / n) ^ (n × t), where n is the number of compounding periods per year and t is the time in years. Interest = A − Principal.

This same arithmetic is commonly used to work out penal or contractual interest on an overdue sum in a demand notice or money-recovery claim — the applicable rate and compounding basis should come from the contract, the promissory note or the relevant statute, not this tool.

Sources & notes

  • Standard simple-interest and compound-interest arithmetic; the applicable rate is usually fixed by contract, a promissory note, or a specific statute (e.g. the MSMED Act 2006 for delayed B2B payments, which has its own dedicated calculator).
  • Courts have discretion to award or moderate interest and penal interest under the Code of Civil Procedure, 1908 (e.g. interest pendente lite and post-decree) and under the Interest Act, 1978.

Treat this result as a planning estimate only. Confirm the applicable rate, compounding basis and any statutory cap with a qualified advocate before relying on it in a notice, claim or filing.

Frequently asked questions

Simple interest is calculated only on the original principal for the entire period. Compound interest is calculated on the principal plus any interest already accrued, added back at each compounding period (monthly, quarterly or annually), so it grows faster over time.

Use the rate specified in the underlying contract, promissory note or invoice terms. If none is specified, courts may award interest under the Interest Act 1978 or the Code of Civil Procedure 1908 at their discretion; MSME/B2B dues have a separate statutory rate under the MSMED Act 2006.

This tool counts the calendar days between the "from" and "to" dates (inclusive of both end dates is not assumed — it is a straight day-count difference) and converts that to years by dividing by 365.

No. This is an indicative estimate using standard interest arithmetic. The rate, compounding basis, and any statutory cap depend on the contract, the applicable law and the facts of your case. Confirm with a qualified advocate before relying on it.

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CaseDocker Credit Workdesk tracks overdue invoices, computes penal/contractual interest and manages the recovery workflow end to end.

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