Fidamen

Convert Miles per Gallon UK to Liters per 100 Kilometers - Fuel Economy Converter

This converter converts fuel economy expressed as miles per imperial gallon (MPG UK) into liters consumed per 100 kilometers (L/100km). Enter a single MPG (UK) value to get the equivalent L/100km value used commonly in Europe and for regulatory comparison.

Results use internationally accepted unit definitions and published constants. The tool reports L/100km derived from exact definitions for the imperial gallon and the mile; see methodology and citations for authoritative sources and accuracy caveats.

Updated Nov 12, 2025QA PASS — golden 25 / edge 120Run golden-edge-2026-01-23

Governance

Record df70ebc920b6 • Reviewed by Fidamen Standards Committee

Interactive converter unavailable for this calculator.

We could not resolve compatible units for this experience. Please verify the slug follows the pattern `from-unit-to-unit-converter`.

Methodology

Calculation uses fixed unit definitions: 1 imperial gallon = 4.54609 liters and 1 mile = 1.609344 kilometers. These are stable international definitions used in measurement standards and referenced by national metrology institutions.

Numerical computation follows standard floating-point practice (IEEE 754 double precision) and is suitable for typical vehicle fuel-economy ranges. Rounding is applied only for display; underlying calculation uses full double-precision arithmetic. For traceability and unit correctness, consult NIST and ISO references listed in citations.

Key takeaways

This is a direct unit conversion using exact unit definitions; no empirical corrections are applied.

Use the numeric formula L/100km = 282.480936 / MPG(UK) for quick manual calculations or verification.

Worked examples

MPG(UK) = 40 → L/100km ≈ 282.480936 / 40 = 7.0620 L/100km

MPG(UK) = 30 → L/100km ≈ 282.480936 / 30 = 9.4160 L/100km

MPG(UK) = 60 → L/100km ≈ 282.480936 / 60 = 4.7080 L/100km

F.A.Q.

Is this conversion exact?

The conversion is exact given the defined constants for the imperial gallon (4.54609 L) and the mile (1.609344 km). The displayed result may be rounded for readability; the underlying arithmetic uses standard double-precision floating point. Small differences can arise from rounding and display formatting.

How does UK/Imperial MPG differ from US MPG?

UK (imperial) and US gallons are different volumes. One imperial gallon is 4.54609 liters while one US gallon is 3.785411784 liters. This converter specifically expects miles per imperial gallon (MPG UK). Using a US-MPG value will produce an incorrect L/100km result.

What input range is sensible?

Typical road vehicle values for MPG (UK) range roughly from 5 to 200. Values below 1 or extremely large values may indicate input error. The calculation itself accepts any positive numeric input but negative or zero values are invalid for fuel economy.

How accurate is the numeric output?

Accuracy is constrained by the defined conversion constants and floating-point representation (IEEE 754). For regulatory or legal purposes, use the exact constants cited and follow local measurement protocols. This tool is suitable for everyday comparisons, planning, and reporting but not a substitute for certified measurement when required.

Can I use this for emissions or cost estimates?

This converter provides only unit conversion between MPG (UK) and L/100km. Emissions or fuel cost calculations require additional inputs (fuel carbon intensity, fuel price, driving distance) and are outside the scope of this tool.

Sources & citations

Further resources

Versioning & Change Control

Audit record (versions, QA runs, reviewer sign-off, and evidence).

Record ID: df70ebc920b6

What changed (latest)

v1.0.0 • 2025-11-12 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Public QA status

PASS — golden 25 + edge 120

Last run: 2026-01-23 • Run: golden-edge-2026-01-23

Engine

v1.0.0

Data

Baseline (no external datasets)

Content

v1.0.0

UI

v1.0.0

Governance

Last updated: Nov 12, 2025

Reviewed by: Fidamen Standards Committee (Review board)

Credentials: Internal QA

Risk level: low

Reviewer profile (entity)

Fidamen Standards Committee

Review board

Internal QA

Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person

Semantic versioning

  • MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
  • MINOR: New features or fields that do not change existing outputs for the same inputs.
  • PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.

Review protocol

  • Verify formulas and unit definitions against primary standards or datasets.
  • Run golden-case regression suite and edge-case suite.
  • Record reviewer sign-off with credentials and scope.
  • Document assumptions, limitations, and jurisdiction applicability.

Assumptions & limitations

  • Uses exact unit definitions from the Fidamen conversion library.
  • Internal calculations use double precision; display rounding follows the unit's configured decimal places.
  • Not a substitute for calibrated instruments in regulated contexts.
  • Jurisdiction-specific rules may require official guidance.

Change log

v1.0.0 • 2025-11-12 • MINOR

Initial publication and governance baseline.

Why: Published with reviewed formulas, unit definitions, and UX controls.

Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: d387453d4715