# EMI Calculator

> Computes the equated monthly instalment (EMI) of a home, car or personal loan from the loan amount, annual interest rate and tenure in months, with the total interest and total amount payable; identical to the standard amortizing-loan payment formula.

- Calculator id: `emi` · Category: Finance (`finance`) · Tool name: `calculate_emi`
- Canonical page: https://tttkmbb.com/finance/emi · This document: https://tttkmbb.com/finance/emi.md · JSON definition: https://tttkmbb.com/finance/emi.json

## Purpose

Computes the equated monthly instalment (EMI) of a home, car or personal loan from the loan amount, annual interest rate and tenure in months, with the total interest and total amount payable; identical to the standard amortizing-loan payment formula.

**Use when:** You want the EMI for a loan quoted with an annual rate and a tenure in months, as is customary in India and other markets that use the EMI term.

**Do not use when:** You need the year-by-year breakdown (use amortization-schedule), or a flat-rate loan where interest is charged on the original principal for the whole term (multiply principal × flat rate × years instead).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `loan_amount` | number |  | required | Principal borrowed. (> 0, max 1000000000000) |
| `annual_rate_percent` | number | % | required | Reducing-balance annual rate in percent; the monthly rate is this / 12. (min 0, max 100) |
| `tenure_months` | integer | months | required | Loan tenure in months (20 years = 240). (min 1, max 480) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `emi` | number |  | Equated monthly instalment. |
| `total_interest` | number |  | emi × tenure_months − loan_amount. |
| `total_payment` | number |  | emi × tenure_months. |
| `interest_share_of_total_percent` | number | % | total_interest / total_payment × 100. |

## Formula

`r = annual_rate_percent / 1200; n = tenure_months; EMI = loan_amount × r × (1 + r)^n / ((1 + r)^n − 1); loan_amount / n when r = 0`

Reducing-balance (diminishing) interest with payments at the end of each month, the formula used by Indian banks and identical to the annuity payment in loan-payment. Processing fees and prepayment charges are not included.

## Data Sources

- Investopedia – Equated Monthly Installment (EMI): Definition and Formula — https://www.investopedia.com/terms/e/equated_monthly_installment.asp (reference, retrieved 2026-09-24)
- Wikipedia – Equated monthly installment — https://en.wikipedia.org/wiki/Equated_monthly_installment (reference, retrieved 2026-09-24)
- Wikipedia – Amortization calculator (annuity payment formula) — https://en.wikipedia.org/wiki/Amortization_calculator (reference, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/emi?loan_amount=…&annual_rate_percent=…&tenure_months=…`
- `POST https://tttkmbb.com/api/v1/calculate/emi` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/emi · OpenAPI operationId `calculate_emi` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "emi", "inputs": {…}}`

## Example

- 10,00,000 at 8.5 % for 240 months: inputs `{"loan_amount":1000000,"annual_rate_percent":8.5,"tenure_months":240}` → `{"emi":8678.23,"total_interest":1082775.76,"total_payment":2082775.76,"interest_share_of_total_percent":51.99}`
- 5,00,000 at 10 % for 60 months: inputs `{"loan_amount":500000,"annual_rate_percent":10,"tenure_months":60}` → `{"emi":10623.52,"total_interest":137411.34,"total_payment":637411.34}`

```
GET https://tttkmbb.com/api/v1/calculate/emi?loan_amount=1000000&annual_rate_percent=8.5&tenure_months=240
```

## Limitations

You need the year-by-year breakdown (use amortization-schedule), or a flat-rate loan where interest is charged on the original principal for the whole term (multiply principal × flat rate × years instead). Reducing-balance (diminishing) interest with payments at the end of each month, the formula used by Indian banks and identical to the annuity payment in loan-payment. Processing fees and prepayment charges are not included. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Is EMI the same as a loan payment?**

Yes. EMI is the Indian-English term for the level monthly payment of an amortizing loan; loan-payment gives the same number for the same inputs (with the term in years and/or months).

**What is the difference between a reducing-balance and a flat rate?**

A flat rate charges interest on the full original principal every year, so a 10 % flat rate costs roughly the same as an 18 % reducing-balance rate over 5 years. Enter the reducing-balance rate here.

## Related

- [Loan Payment Calculator](https://tttkmbb.com/finance/loan-payment.md) — Same formula with the term in years or months.
- [Amortization Schedule Calculator](https://tttkmbb.com/finance/amortization-schedule.md) — Year-by-year principal and interest split.
- [Debt Payoff Calculator](https://tttkmbb.com/finance/debt-payoff.md) — Payoff time for a chosen payment.