What size crown caps do I need?

Standard UK homebrew bottles use 26mm crown caps. Some older or specialty bottles (particularly some Belgian-style bottles) use 29mm caps. Check your bottles before ordering — the wrong size will not seal properly and you risk flat beer or contamination.

Can I reuse crown caps?

No. Crown caps are single-use only. The liner deforms when crimped and will not seal properly a second time. Always use new caps. Swing-top bottles with rubber gaskets can be reused many times — just replace the gasket occasionally.

How many spares should I buy?

Buy at least 10% extra. Caps are cheap and you will inevitably drop a few, get a bad crimp, or need extras for topping up. Since they come in packs of 100, it is often easiest to just buy the next pack size up.

Do I need to sanitise bottle caps?

Yes. Soak caps in sanitiser solution (e.g., Star San) for a few minutes before use. Some oxygen-absorbing caps should not be soaked for too long as the liner can be affected. Check the manufacturer instructions for oxygen-absorbing caps.

Are oxygen-absorbing caps worth using?

Oxygen-absorbing caps help reduce oxidation for beers you plan to age. They absorb small amounts of headspace oxygen during conditioning. For beers consumed within a few months, standard caps are perfectly adequate.

BrewCalcs

Cap Calculator

Calculate bottle caps or crown seals needed including spares.

Bottles per Batch

Number of bottles

Number of Batches

Planning ahead for multiple brews

Cap Type

Spare Caps

Enter the spare caps

How We Calculate This

Cap Count

The calculation is straightforward: Caps Needed = Bottles per Batch x Number of Batches. Spare caps are added as a percentage. The pack count rounds up to the nearest full pack (typically sold in 100s for crown caps, 25s for corks).

Frequently Asked Questions

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Last updated: 2025-02-20

All calculations are estimates. Always verify values and adjust based on your equipment and ingredients.