Lime vs Key Lime: What's the Difference?
Short answer: The common supermarket lime is the Persian lime — large, seedless, and less acidic. The key lime is smaller, seedier, thinner-skinned and far more aromatic, with sharper acidity. Key lime is the traditional lime of key lime pie and the classic daiquiri.
| 🍈 Lime | 🟢 Key lime | |
|---|---|---|
| Taste | Bracing, slightly bitter-edged acidity with a resinous, distinctly "green" aroma. Key limes are smaller, seedier, and more aromatic-tart; makrut leaves carry an irreplaceable citrus-floral perfume. | Sharper, more floral, and more complex than a Persian lime, with thin skin, many seeds, and a heady aroma; the juice is prized for perfume as much as acidity. |
| Type | Citrus | Citrus |
| Peak season | Year-round | Summer, Autumn |
| Origin | Southeast Asia (likely Indonesia/Malaysia region); carried west by Arab traders, to the Americas by the Spanish | Southeast Asia; carried by traders to the Americas, naturalized in the Caribbean and Mexico |
| Calories (per 100 g) | 30 | 30 |
| Sugar (per 100 g) | 1.7 g | 1.7 g |
| Vitamin C (per 100 g) | 29.1 mg | 29 mg |
| Typical price | Budget | Budget |
Reach for a “lime” in most shops and you’ll get a Persian lime: large, deep green, seedless, and relatively mild. It’s the workhorse lime — juicy, convenient, and less punishing than its smaller cousin.
The key lime is a different fruit: smaller, often yellowing as it ripens, with thin skin, several seeds, and a thin but intensely aromatic juice. It’s noticeably more tart and more floral than a Persian lime, which is exactly why it defines key lime pie and the classic daiquiri. The trade-off is practicality — key limes are fiddly to juice and more perishable, so Persian limes dominate the shelves.
Substituting works both ways with adjustments: use extra Persian lime juice to chase a key lime’s sharpness, or dial back if a recipe built for Persian limes calls for the more concentrated key lime.
Frequently asked questions
Are key limes and regular limes the same?
No. Most shop limes are Persian limes — larger and seedless. Key limes are a different, smaller, seedier variety with thinner skin, more aroma, and higher acidity.
Can I use regular limes instead of key limes?
Yes, in a pinch. Persian limes are less aromatic and less tart, so the result is milder. Use a little extra juice to approximate a key lime's punch.
Why are key limes used in key lime pie?
Key limes give a sharper, more floral, more intense lime flavour than Persian limes, which is the traditional taste of the pie from the Florida Keys.