Alcohol DilutionUS Proof to UK Proof

US Proof to UK Proof for Alcohol Strength

Snapshot

1 US Proof equals 0.874891 UK Proof. Conversion Encyclopedia uses the same fixed conversion basis across the calculator, common values, and reverse page for this page.

Reference basis: This result uses fixed ABV and proof definitions for the selected alcohol-strength pair.
Example: For 0.25 US Proof, the result equals 0.218723 UK Proof.
Use the reverse page if you need the opposite direction with the same basis.

Use the interactive calculator below for custom values and the common-value table for quick checks.

Interactive conversion

Converter Calculator

0.874891 UK Proof (proof (UK))

Switch

Machine access

Available to apps and AI agents

US Proof to UK Proof for Alcohol Strength can be requested through Conversion Encyclopedia's structured interfaces by software and compatible AI agents. The identifiers below select the same calculation as the calculator.

Machine-readable identifiers

Conversion family: alcohol-dilution
Source unit: us_proof
Target unit: uk_proof

The JSON API and OpenAPI specification use the identifiers to reach the conversion engine. WebMCP lets compatible AI agents request the same calculation.

Example API request and response

POST /api/v1/convert

Request

{
  "family": "alcohol-dilution",
  "value": 1,
  "from": "us_proof",
  "to": "uk_proof"
}

Essential response

{
  "ok": true,
  "conversion": {
    "family": "alcohol-dilution",
    "value": 1,
    "from": "us_proof",
    "to": "uk_proof",
    "result": {
      "raw": 0.87489063867,
      "display": "0.874891"
    },
    "canonicalPath": "/alcohol-dilution/us-proof-to-uk-proof/"
  }
}

Full API documentation

Explanation

Formula: UK Proof = US Proof × 0.874891. Why: proof scales are normalized through ABV percent using fixed legal definitions, including US proof = 2 times ABV and 100 UK proof = 57.15% ABV.

US Proof (proof (US)): a spirits-strength scale defined as exactly 2 times ABV percent.

UK Proof (proof (UK)): a historical proof scale where 100 proof equals 57.15% ABV.

This route is useful when translating between ABV and proof systems for beverage labeling, spirits references, and dilution planning.

This conversion is purely multiplicative because both strength scales reduce through ABV percent using fixed proof and fractional definitions with no offset.

Method & Strength Basis

Method basis: fixed alcohol-strength definitions normalized through ABV percent, including the exact US and UK proof relationships used on this page.
Applied factor: 1 US Proof = 0.874891 UK Proof.
Consistency rule: calculator output and common-value rows use the same ABV-based strength constants in both directions.

Common Conversion Values

US Proof (proof (US))	UK Proof (proof (UK))
0.25	0.218723
0.5	0.437445
1	0.874891
5	4.374453
12	10.498688
20	17.497813
40	34.995626
57.15	50
80	69.991251
100	87.489064

Questions & answers

Frequently Asked Questions

How many proof (UK) are in 1 proof (US)?

1 proof (US) equals 0.87489063867 proof (UK) on this page.

Why does this route go through ABV percent?

ABV percent is the common reference layer for this family, so proof, fraction, and per-mille strength values stay consistent and reversible.

How do I reverse US Proof to UK Proof?

Use the switch button or open the UK Proof to US Proof page to apply the same alcohol-strength relationship in reverse.

Can I use decimal inputs?

Yes. Decimal strength values are supported for beverage labeling, spirits references, lab work, and batching calculations.