# Force Converter

> Converts force between newtons (N, kN), dynes, gram-force, kilogram-force (kilopond), ounce-force, pound-force and kips using exact factors (1 lbf = 4.4482216152605 N, 1 kgf = 9.80665 N).

- Calculator id: `force` · Category: Unit Conversion (`conversion`) · Tool name: `convert_force`
- Canonical page: https://tttkmbb.com/conversion/force · This document: https://tttkmbb.com/conversion/force.md · JSON definition: https://tttkmbb.com/conversion/force.json

## Purpose

Converts force between newtons (N, kN), dynes, gram-force, kilogram-force (kilopond), ounce-force, pound-force and kips using exact factors (1 lbf = 4.4482216152605 N, 1 kgf = 9.80665 N).

**Use when:** You need a load, thrust or weight-force in another unit, e.g. lbf to N, kgf to N or kN to kips for structural loads.

**Do not use when:** You need to compute force from mass and acceleration (Newton's second law is a physics calculation, not a unit conversion), a spring force (use hookes-law) or plain mass units (use mass).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `value` | number |  | required | Amount to convert, expressed in from_unit. |
| `from_unit` | enum: N \| kN \| dyn \| gf \| kgf \| ozf \| lbf \| kip |  | required | Unit of the input value. Accepted symbols: N, kN, dyn, gf, kgf, ozf, lbf, kip; spelled-out names and common abbreviations are accepted too. |
| `to_unit` | enum: N \| kN \| dyn \| gf \| kgf \| ozf \| lbf \| kip |  | required | Unit to convert into (same symbols as from_unit). |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `result` | number |  | Converted value expressed in to_unit (rounded to 6 decimals; see result_text for very small or very large values). |
| `result_text` | string |  | The conversion as text with 6 significant figures, e.g. "5 mi = 8.04672 km". |
| `formula` | string |  | Relation used, e.g. "1 mi = 1.609344 km". |
| `factor` | number |  | Multiplier from from_unit to to_unit (result = value × factor); absent for non-linear conversions. |
| `conversion_table` | object |  | The input value expressed in every supported force unit (6 significant figures), keyed by unit symbol. |

## Formula

`result = value × factor, factor = (1 from_unit in N) / (1 to_unit in N)`

kgf and lbf are the weights of 1 kg and 1 lb under standard gravity gₙ = 9.80665 m/s²; a mass in kg therefore has the same numeric value in kgf.

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-23)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-23)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (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/force?value=…&from_unit=…&to_unit=…`
- `POST https://tttkmbb.com/api/v1/calculate/force` 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/force · OpenAPI operationId `convert_force` 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": "force", "inputs": {…}}`

## Example

- 100 pounds-force to newtons: inputs `{"value":100,"from_unit":"lbf","to_unit":"N"}` → `{"result":444.822162,"factor":4.4482216153,"formula":"1 lbf = 4.448221615 N","conversion_table":{"kgf":45.3592,"kN":0.444822}}`
- 500 N to kilograms-force: inputs `{"value":500,"from_unit":"N","to_unit":"kgf"}` → `{"result":50.985811,"conversion_table":{"lbf":112.404,"dyn":50000000}}`

```
GET https://tttkmbb.com/api/v1/calculate/force?value=100&from_unit=lbf&to_unit=N
```

## Limitations

You need to compute force from mass and acceleration (Newton's second law is a physics calculation, not a unit conversion), a spring force (use hookes-law) or plain mass units (use mass). kgf and lbf are the weights of 1 kg and 1 lb under standard gravity gₙ = 9.80665 m/s²; a mass in kg therefore has the same numeric value in kgf. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Is kgf the same as kg?**

No. kg is mass; kgf is the force exerted by 1 kg under standard gravity (9.80665 N). On Earth the numbers match, which is why scales are labelled in kg.

**What is a kip?**

A kilopound-force, 1000 lbf = 4448.22 N, used in US structural engineering.

## Related

- [Mass / Weight Converter](https://tttkmbb.com/conversion/mass.md) — Mass units behind kgf and lbf.
- [Torque Converter](https://tttkmbb.com/conversion/torque.md) — Force × lever arm units (N·m, lbf·ft).
- [Hooke's Law Calculator](https://tttkmbb.com/physics/hookes-law.md) — Spring force from stiffness and displacement.