For chemical leavening: small weight changes alter rise and browning.
1 cup of Cornstarch in ounces
Reviewed by CupOrGram Editorial TeamData methodology: NIST-derived density references + recipe testing notesMethodology
Answer
4.5 ounces
Based on cornstarch density of 0.54 g/ml
Source: NIST-DB-72
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Need a substitute for Cornstarch?
We have 3 tested substitutions with exact ratios.
View substitutions →Quick Reference Table
| cups | ounces |
|---|---|
| 1/4 cups | 1.1 ounces |
| 1/3 cups | 1.5 ounces |
| 1/2 cups | 2.3 ounces |
| 1 cups | 4.5 ounces |
| 1.50 cups | 6.8 ounces |
| 2 cups | 9.0 ounces |
| 3 cups | 13.5 ounces |
| 4 cups | 18.0 ounces |
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Density-accurate conversions for baking
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ounces
Science Note: Precision within +/-0.002g
Why this conversion matters
Cornstarch has a density of 0.54 g/ml, which means it's moderately light — a cup weighs less than you might expect. Using weight-based measurements gives you consistent results every time.
Recipe Context for Cornstarch
For quick breads: over-leavening can cause collapse after oven spring.
For cookies: balance leavening with acid source for predictable spread.
Common Pitfalls
- Switching brands without re-checking weight can change texture and bake time.
- Using volume-only measurements for dense ingredients can overshoot recipe targets.
- Expired leaveners can underperform even when measured correctly.
Brand Variance Example
Baseline on this page: 1 cup cornstarch = 128g. Real-world range can shift by about 6% because fine powders and leaveners settle during storage, changing cup density.
Example for 2 cups: baseline 256g, common range 240g-272g. If your bake is texture-sensitive, start with the lower bound and adjust after a test batch.