# Present Value Calculator

> Discounts a single future amount back to today's value at a constant annual rate and compounding frequency, and reports the discount factor and the amount of discount.

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

## Purpose

Discounts a single future amount back to today's value at a constant annual rate and compounding frequency, and reports the discount factor and the amount of discount.

**Use when:** You need to know what a future sum is worth today, e.g. to compare a lump sum now against a payment later, or to price a zero-coupon bond.

**Do not use when:** You need the value of a stream of payments (use future-value for accumulation, or a dedicated annuity/NPV tool), or you want to grow money forward (use future-value).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `future_value` | number |  | required | Amount to be received or paid in the future. (min 0, max 1000000000000) |
| `annual_rate_percent` | number | % | required | Nominal annual rate of return or cost of capital in percent. (min 0, max 100) |
| `years` | number | years | required | Time until the future amount is due. (> 0, max 200) |
| `compounding_frequency` | enum: annually \| semiannually \| quarterly \| monthly \| weekly \| daily |  | optional, default "annually" | How often interest is credited: n = 1, 2, 4, 12, 52 or 365 periods per year. |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `present_value` | number |  | future_value / (1 + i)^n. |
| `discount_factor` | number |  | (1 + i)^−n, the multiplier applied to the future value. |
| `discount_amount` | number |  | future_value − present_value (interest forgone). |
| `number_of_periods` | number |  | n = periods per year × years. |
| `periodic_rate_percent` | number | % | i = annual rate / periods per year. |

## Formula

`i = annual_rate_percent/100 / n_per_year; n = n_per_year × years; present_value = future_value / (1 + i)^n; discount_factor = (1 + i)^−n`

## Data Sources

- Investopedia – Present Value (PV): Formula and Calculation — https://www.investopedia.com/terms/p/presentvalue.asp (reference, retrieved 2026-09-23)
- Wikipedia – Present value — https://en.wikipedia.org/wiki/Present_value (reference, retrieved 2026-09-23)

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/present-value?future_value=…&annual_rate_percent=…&years=…`
- `POST https://tttkmbb.com/api/v1/calculate/present-value` 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/present-value · OpenAPI operationId `calculate_present_value` 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": "present-value", "inputs": {…}}`

## Example

- 10,000 in 10 years at 5 % (annual): inputs `{"future_value":10000,"annual_rate_percent":5,"years":10,"compounding_frequency":"annually"}` → `{"present_value":6139.13,"discount_factor":0.613913,"discount_amount":3860.87,"number_of_periods":10}`
- 100,000 in 20 years at 6 % (annual): inputs `{"future_value":100000,"annual_rate_percent":6,"years":20}` → `{"present_value":31180.47,"discount_factor":0.311805}`

```
GET https://tttkmbb.com/api/v1/calculate/present-value?future_value=10000&annual_rate_percent=5&years=10&compounding_frequency=annually
```

## Limitations

You need the value of a stream of payments (use future-value for accumulation, or a dedicated annuity/NPV tool), or you want to grow money forward (use future-value). All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Which discount rate should I use?**

The return you could earn on an alternative of similar risk: a savings or bond yield for safe cash flows, a higher required return for risky ones.

**Does compounding frequency change the answer?**

Slightly: more frequent compounding at the same nominal rate discounts more heavily. 10,000 in 10 years at 5 % is 6,139.13 with annual and 6,071.61 with monthly compounding.

## Related

- [Future Value Calculator](https://tttkmbb.com/finance/future-value.md) — Grow a present amount forward instead.
- [Inflation Calculator](https://tttkmbb.com/finance/inflation.md) — Discount by inflation to get purchasing power rather than investment value.