# US tablespoons to US teaspoons (tbsp to tsp)

> Convert US tablespoons to US teaspoons: 1 tbsp = 3 tsp. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `tablespoons-to-teaspoons` · Quantity: Volume (`volume`, base unit L) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/tablespoons-to-teaspoons · This document: https://tttkmbb.com/conversion/tablespoons-to-teaspoons.md · JSON: https://tttkmbb.com/conversion/tablespoons-to-teaspoons.json (add `?value=` for a result)

## Formula

- `1 tbsp = 3 tsp`
- `US teaspoons = US tablespoons × 3`
- Reverse: `US tablespoons = US teaspoons × 0.3333333333`

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 tbsp = 15 tsp
- 12.5 tbsp = 37.5 tsp
- 100 tbsp = 300 tsp

## Conversion table

| US tablespoons (tbsp) | US teaspoons (tsp) |
| --- | --- |
| 1 | 3 |
| 2 | 6 |
| 3 | 9 |
| 4 | 12 |
| 5 | 15 |
| 6 | 18 |
| 7 | 21 |
| 8 | 24 |
| 9 | 27 |
| 10 | 30 |
| 15 | 45 |
| 20 | 60 |
| 25 | 75 |
| 30 | 90 |
| 40 | 120 |
| 50 | 150 |
| 75 | 225 |
| 100 | 300 |
| 200 | 600 |
| 250 | 750 |
| 500 | 1500 |
| 1000 | 3000 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=tbsp&to_unit=tsp` → 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":"tbsp","to_unit":"tsp"}`
- All volume units: https://tttkmbb.com/api/v1/units?quantity=volume · full converter: [Volume Converter](https://tttkmbb.com/conversion/volume.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many US teaspoons are in one tablespoon?**

1 tbsp = 3 tsp. 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 US tablespoons to US teaspoons?**

Multiply the value in US tablespoons by 3: US teaspoons = US tablespoons × 3. For example, 5 tbsp = 15 tsp.

**How do I convert US teaspoons back to US tablespoons?**

Multiply by the inverse factor 0.3333333333 (US tablespoons = US teaspoons × 0.3333333333), or use the US teaspoons-to-US tablespoons page.

## Related conversions

- [US teaspoons to US tablespoons](https://tttkmbb.com/conversion/teaspoons-to-tablespoons.md) (reverse)
- [Liters to US gallons](https://tttkmbb.com/conversion/liters-to-gallons.md)
- [US gallons to Liters](https://tttkmbb.com/conversion/gallons-to-liters.md)
- [Milliliters to US fluid ounces](https://tttkmbb.com/conversion/ml-to-fl-oz.md)
- [US fluid ounces to Milliliters](https://tttkmbb.com/conversion/fl-oz-to-ml.md)
- [Liters to Milliliters](https://tttkmbb.com/conversion/liters-to-ml.md)
- [Milliliters to Liters](https://tttkmbb.com/conversion/ml-to-liters.md)
- [US cups to Milliliters](https://tttkmbb.com/conversion/cups-to-ml.md)
- [Milliliters to US cups](https://tttkmbb.com/conversion/ml-to-cups.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)