# Square inches to Square feet (in² to ft²)

> Convert square inches to square feet: 1 in² = 0.00694444 ft². Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `square-inches-to-square-feet` · Quantity: Area (`area`, base unit m2) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/square-inches-to-square-feet · This document: https://tttkmbb.com/conversion/square-inches-to-square-feet.md · JSON: https://tttkmbb.com/conversion/square-inches-to-square-feet.json (add `?value=` for a result)

## Formula

- `1 in² = 0.00694444 ft²`
- `square feet = square inches × 0.006944444444`
- Reverse: `square inches = square feet × 144`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 in² = 0.0347222 ft²
- 12.5 in² = 0.0868056 ft²
- 100 in² = 0.694444 ft²

## Conversion table

| Square inches (in²) | Square feet (ft²) |
| --- | --- |
| 1 | 0.00694444 |
| 2 | 0.0138889 |
| 3 | 0.0208333 |
| 4 | 0.0277778 |
| 5 | 0.0347222 |
| 6 | 0.0416667 |
| 7 | 0.0486111 |
| 8 | 0.0555556 |
| 9 | 0.0625 |
| 10 | 0.0694444 |
| 15 | 0.104167 |
| 20 | 0.138889 |
| 25 | 0.173611 |
| 30 | 0.208333 |
| 40 | 0.277778 |
| 50 | 0.347222 |
| 75 | 0.520833 |
| 100 | 0.694444 |
| 200 | 1.38889 |
| 250 | 1.73611 |
| 500 | 3.47222 |
| 1000 | 6.94444 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=in2&to_unit=ft2` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"in2","to_unit":"ft2"}`
- All area units: https://tttkmbb.com/api/v1/units?quantity=area · full converter: [Area Converter](https://tttkmbb.com/conversion/area.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many square feet are in one square inch?**

1 in² = 0.00694444 ft². The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

**What is the formula to convert square inches to square feet?**

Multiply the value in square inches by 0.006944444444: square feet = square inches × 0.006944444444. For example, 5 in² = 0.0347222 ft².

**How do I convert square feet back to square inches?**

Multiply by the inverse factor 144 (square inches = square feet × 144), or use the square feet-to-square inches page.

## Related conversions

- [Square feet to square inches](https://tttkmbb.com/conversion/square-feet-to-square-inches.md) (reverse)
- [Square meters to Square feet](https://tttkmbb.com/conversion/square-meters-to-square-feet.md)
- [Square feet to Square meters](https://tttkmbb.com/conversion/square-feet-to-square-meters.md)
- [Acres to Hectares](https://tttkmbb.com/conversion/acres-to-hectares.md)
- [Hectares to Acres](https://tttkmbb.com/conversion/hectares-to-acres.md)
- [Acres to Square meters](https://tttkmbb.com/conversion/acres-to-square-meters.md)
- [Square meters to Acres](https://tttkmbb.com/conversion/square-meters-to-acres.md)
- [Square kilometers to Square miles](https://tttkmbb.com/conversion/square-km-to-square-miles.md)
- [Square miles to Square kilometers](https://tttkmbb.com/conversion/square-miles-to-square-km.md)

## 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 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)