Free Online Unit Converter — Convert Length, Weight, Temperature, Speed, Area, Volume, Data, and Time Instantly

There are three kinds of unit conversion moments:

1. You're reading a recipe and it says 350°F, and your oven is in Celsius.
2. You're looking at specs from a US client that uses inches, pounds, and miles.
3. You're estimating storage and need to know how many gigabytes are in 1.2 terabytes.

The Unit Converter on UltimateTools covers all of them — 8 categories, 60+ units, live conversion as you type. No signup, no install.

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The 8 Categories

Length

Covers: km, m, cm, mm, mile, yard, foot, inch.

Common uses:

• 100 km → 62.14 miles (road distances, running events)
• 6 ft → 182.88 cm (height conversions for international profiles)
• 1 inch → 2.54 cm (screen sizes, hardware specs)
• 5 mm → 0.197 inches (engineering tolerances)

Weight

Covers: metric tonne, kg, g, mg, pound, ounce.

Common uses:

• 80 kg → 176.37 lbs (weight for US forms)
• 1 lb → 453.59 g (recipes with US measurements)
• 500 mg → 0.5 g (medication dosages)
• 2.5 tonnes → 2,500 kg (shipping, cargo)

Temperature

Covers: Celsius, Fahrenheit, Kelvin.

Temperature is the one category where you can't just multiply by a number — the scales have different zero points. The converter handles the full formula automatically.

Common uses:

• 100°C → 212°F (boiling point)
• 350°F → 176.67°C (oven temperatures from US recipes)
• 37°C → 98.6°F (body temperature)
• 0 K → -273.15°C (absolute zero, physics)

Speed

Covers: km/h, m/s, mph, knots.

Common uses:

• 100 km/h → 62.14 mph (speed limits, vehicle specs)
• 30 m/s → 108 km/h (physics problems)
• 15 knots → 27.78 km/h (maritime, aviation)

Area

Covers: km², m², cm², ft², acre, hectare.

Common uses:

• 1 acre → 4046.86 m² (land area)
• 1 hectare → 2.47 acres (agriculture)
• 500 ft² → 46.45 m² (apartment sizes from US listings)
• 1 km² → 100 hectares (city planning)

Volume

Covers: m³, litre, millilitre, US gallon, US fluid ounce, US cup.

Common uses:

• 1 US gallon → 3.785 litres (fuel tank, paint)
• 250 mL → 1.057 US cups (cooking conversions)
• 1 m³ → 1,000 litres (water tanks, pools)
• 8 fl oz → 236.59 mL (US beverage sizes)

Data

Covers: TB, GB, MB, KB, B (binary: 1 KB = 1,024 bytes).

Common uses:

• 1 TB → 1,024 GB (storage devices)
• 500 MB → 512,000 KB (file size limits)
• 4 GB → 4,096 MB (RAM, USB drive specs)
• 2.5 GB → 2,560 MB (video file sizes)

Time

Covers: year, month (30 days), week, day, hour, minute, second.

Common uses:

• 1 year → 31,536,000 seconds (uptime SLAs, Unix timestamps)
• 90 days → 12.86 weeks (project timelines)
• 3 hours → 10,800 seconds (time limits, media duration)
• 1 week → 168 hours (scheduling)

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How It Works

1. Click the category tab (Length, Weight, Temperature, etc.)
2. Select your "From" unit in the left dropdown
3. Type a value
4. Select your "To" unit in the right dropdown
5. The result appears instantly — no submit button needed

The swap button (⇄) flips the direction without retyping your value. Useful for checking your answer.

For very large or very small values (like converting bytes to terabytes or milliseconds to years), the result switches to scientific notation automatically so it stays readable.

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Works Offline

The converter is entirely browser-side — no server calls for calculations. Once the page loads, conversions work even without an internet connection.

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The full Unit Converter is free, no signup required, and covers all 8 categories with 60+ units.