---
title: "21 mL to cup = 0.088762 cup"
description: "21 milliliters is 0.088762 US cups. The arithmetic, a table of nearby values, and a converter for any other number."
url: https://atoneplace.net/convert/21-ml-to-cups/
site: "At One Place"
---

# 21 mL to cup

**21 milliliters in US cups: 21 mL = 0.088762 cup**

cup = mL × 0.004226752838

21 milliliters is 0.088762 US cups. To get there, multiply by 0.004226752838.

## Values either side

*Milliliters near 21, converted to US cups.*

| Milliliters | US cups |
| --- | --- |
| 17 mL | 0.071855 |
| 18 mL | 0.076082 |
| 19 mL | 0.080308 |
| 20 mL | 0.084535 |
| 21 mL ← | 0.088762 |
| 22 mL | 0.092989 |
| 23 mL | 0.097215 |
| 24 mL | 0.10144 |
| 25 mL | 0.10567 |

## How the conversion works

The relationship is cup = mL × 0.004226752838. 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 mL in US cups?

21 mL is 0.088762 cup.

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

Multiply by 0.004226752838.

## Related pages

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