---
title: "21 tsp to cup = 0.4375 cup"
description: "21 teaspoons is 0.4375 US cups. The arithmetic, a table of nearby values, and a converter for any other number."
url: https://atoneplace.net/convert/21-teaspoons-to-cups/
site: "At One Place"
---

# 21 tsp to cup

**21 teaspoons in US cups: 21 tsp = 0.4375 cup**

cup = tsp × 1/48

21 teaspoons is 0.4375 US cups. To get there, multiply by 0.02083333333.

## Values either side

*Teaspoons near 21, converted to US cups.*

| Teaspoons | US cups |
| --- | --- |
| 17 tsp | 0.35417 |
| 18 tsp | 0.375 |
| 19 tsp | 0.39583 |
| 20 tsp | 0.41667 |
| 21 tsp ← | 0.4375 |
| 22 tsp | 0.45833 |
| 23 tsp | 0.47917 |
| 24 tsp | 0.5 |
| 25 tsp | 0.52083 |

## How the conversion works

The relationship is cup = tsp × 1/48. Both units measure volume, so the conversion is a fixed factor that never changes. The figure is exact rather than approximate: since the international yard and pound agreement of 1959, an inch is defined as exactly 25.4 millimetres and a pound as exactly 0.45359237 kilograms, and every other imperial and US customary unit here is derived from those two.

> US cup: US legal cup is 240 mL; the customary cup used here is 236.588 mL.

## Common questions

### What is 21 tsp in US cups?

21 tsp is 0.4375 cup.

### How do you convert teaspoons to US cups?

Multiply by 0.02083333333.

## Related pages

- [Teaspoons to US cups](https://atoneplace.net/convert/teaspoons-to-cups/)
- [21 cup to tsp](https://atoneplace.net/convert/21-cups-to-teaspoons/)
- [17 tsp to cup](https://atoneplace.net/convert/17-teaspoons-to-cups/)
- [18 tsp to cup](https://atoneplace.net/convert/18-teaspoons-to-cups/)
- [19 tsp to cup](https://atoneplace.net/convert/19-teaspoons-to-cups/)
- [20 tsp to cup](https://atoneplace.net/convert/20-teaspoons-to-cups/)
- [22 tsp to cup](https://atoneplace.net/convert/22-teaspoons-to-cups/)
- [23 tsp to cup](https://atoneplace.net/convert/23-teaspoons-to-cups/)
- [24 tsp to cup](https://atoneplace.net/convert/24-teaspoons-to-cups/)
- [25 tsp to cup](https://atoneplace.net/convert/25-teaspoons-to-cups/)

## Sources

- Guide for the Use of the International System of Units (SP 811) — NIST (https://www.nist.gov/pml/special-publication-811) [Public domain (US Government)]
- The International System of Units (SI Brochure) — Bureau International des Poids et Mesures (https://www.bipm.org/en/publications/si-brochure)
- Calculated on this page — At One Place (/about/)