UniRulerUniversal ruler

Length Conversion Calculator

Convert lengths between metric and imperial units. Combine different measurements, see several results at once, and compare familiar objects.

From

Add your lengths together and convert the total.

Up to 10 inputs. Try 1e100 or 10^100 (exponent limit: 100000). Empty rows are not included.

To

5 in

≈0.416667ft
12.7cm
0.127m

≈ marks a rounded result or an approximate object reference.

Try an example

Convert multiple lengths in one calculator

Enter a length in metres, centimetres, inches or feet, then choose the units for your results. Use Combine to add lengths written in different units, or Compare to see separate conversions side by side. For example, 5 ft + 8 in equals exactly 172.72 cm.

Common exact length conversions
FromEqual to
1 inch2.54 centimetres
1 foot12 inches
1 metre100 centimetres
1 mile1.609344 kilometres

For a real-world sense of scale, browse our sourced object measurements. These comparisons describe length only, not area, volume, weight or whether items physically fit. Read our measurement methodology for source details and approximate values.

How measurements and object references work

Every entry represents one length: an inch, a paper edge, an apple diameter, or a full aircraft wingspan. We convert that length into metres, then into each selected output. Combine adds your inputs together; Compare separately keeps each input independent.

Standard unit relationships are exact. Objects use a specified reference size; choose Size & source to see its dimension and evidence. Natural objects vary. These comparisons describe length only; they do not calculate packing, area, weight, or whether objects physically fit.

Read the measurement methodology (new tab) · Catalogue versions (new tab)

A useful sense of scale

Sourced collections for teaching, writing, and exploring.

01Everyday measurementsFamiliar sizes for the classroom (new tab)02Aircraft & spacecraftPut extraordinary sizes in context (new tab)03The reference libraryMeasurements, definitions, and sources (new tab)

Choose a unit or object

Grow the reference library

Suggest an object

Know a useful size? Add its source and explain exactly what it measures. Every suggestion goes to a private queue for an editor to check.

Submit a source → Editorial review → Approval & releaseWe check the measurement, context and duplicates before approval. Suggestions never publish automatically.

Reference details

A little perspective, worth sharing

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Your quantities, selected references, and results will be visible to everyone. Your name is not included.

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Privacy & references
Normal calculations stay in this browser. We do not automatically save your amounts, send them to an AI service, or add them to the public log.
A comparison link contains its selected quantities and references. Anyone you give that link to can see them. Public sharing is a separate, deliberate action.
Object suggestions request a dimension, measurement and public source link, with no name or account. They go to a private review queue with a 90-day retention period and daily cleanup. Accepted factual references are added in a new catalogue edition. Avoid personal measurements and contact details.
Public posts have no name or profile. Short-lived, protected network identifiers may be used to limit spam. Cloudflare processes technical information to deliver the site and, when you choose to publish or suggest a reference, check for bots.
The log is bounded by age and size. After publishing, this browser can keep a private removal key so you can remove your entry. Clearing browser data can remove that key. Removing a log entry does not erase copies already shared elsewhere.
Each object has a selected measurement and a source. Sources are shown in its reference details. The catalogue is versioned so a changed reference cannot silently change an older comparison.