Can I convert between categories, like weight to volume?

No — conversions only work within the same category, since units from different categories aren't directly comparable without extra context like density.

Which unit systems are covered?

Both metric (meters, kilograms, liters) and imperial/US customary (feet, pounds, gallons) units, within each category.

Can I convert Celsius or Fahrenheit here too?

No — temperature uses a different kind of conversion (an offset, not just a multiplication factor), so it has its own dedicated Temperature Converter.

Why do From and To reset when I change category?

Each category has its own unit list, so switching categories picks new default units automatically rather than carrying over units that don't apply.

Why did it open with different default units than I expected?

It opens with region-appropriate defaults — feet and miles for imperial regions, meters and kilometers for metric ones — based on your detected or selected region. You can still change either unit freely regardless of that starting point.

Can I compare the same value across three or more units at once?

Not in one view — only From and To are shown at a time. Change the To unit to check a different comparison using the same From value and amount.

Does Volume use the US gallon or the larger UK imperial gallon?

The US gallon (about 3.785 liters) — this tool uses standard international conversion factors rather than region-specific unit variants like the UK's larger imperial gallon.

Can I convert a negative value, like -5 feet of elevation change?

Yes — there's no zero-floor on the Value field, so a negative number converts to its negative equivalent in the target unit, unlike some of this site's other converters that clamp inputs to zero.

Unit Converter

About the Unit Converter

Converts between common units of length, weight, volume, and area using standard conversion factors, across metric and imperial systems.

100% Free Runs in Your Browser No Sign-Up Required

How to use it

Choose a Category — length, weight, volume, or area.
Select the From and To units.
Enter a Value.
Read the converted result in the readout.

Formula

Value in target unit = (Value × factor of source unit) ÷ factor of target unit, where each factor expresses that unit relative to a shared base unit for its category.

Worked example

5 miles converts to about 8.05 kilometers, using the standard factor of 1 mile = 1.60934 km.

Conversion factors by category

Conversion factors by category
Category	Unit	Factor (relative to base unit)
Length	m (base)	1
Length	km	1,000
Length	cm	0.01
Length	mm	0.001
Length	mi	1,609.34
Length	yd	0.9144
Length	ft	0.3048
Length	in	0.0254
Weight	kg (base)	1
Weight	g	0.001
Weight	mg	0.000001
Weight	lb	0.453592
Weight	oz	0.0283495
Weight	ton	1,000
Volume	L (base)	1
Volume	mL	0.001
Volume	gal (US)	3.78541
Volume	qt	0.946353
Volume	pt	0.473176
Volume	cup	0.24
Volume	fl oz	0.0295735
Area	m² (base)	1
Area	km²	1,000,000
Area	ft²	0.092903
Area	yd²	0.836127
Area	acre	4,046.86
Area	hectare	10,000

Recommendations

• Double-check which system, metric or imperial, you actually need before reading the result — it's easy to grab the wrong one.
• For cooking, volume conversions are more error-prone than weight — a kitchen scale plus this tool avoids guesswork.
• Very large or small conversions, like area in acres to square meters, benefit from double-checking the decimal placement.

Frequently asked questions

They use standard published conversion factors at full floating-point precision, rounded for display to a few decimal places.

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