Unit Converter (length, mass, temperature, KB vs KiB, Mbps vs MB/s)
Pick a category, type a value, and convert as you type. Temperature uses real offsets; KB and KiB stay distinct.
Sending to the cloud or a friend? Put your upload speed in the From box; on most home lines it's far lower than the download speed.
How it works
Choose a category — length, mass, temperature, data size or data rate — then a value and the from/to units. The result updates as you type. Everything runs in your browser; nothing is uploaded.
Length is based on the metre (m, km, cm, mm, mi, yd, ft, in, and the international nautical mile). Mass is based on the kilogram (kg, g, mg, lb, oz, and t for the metric tonne = 1000 kg). A US short ton is 2000 lb and a UK long ton is 2240 lb — convert those via pounds so the locale stays visible.
Temperature is not a simple multiply. The tool converts through Kelvin with the standard offsets (°C = K − 273.15, °F = °C × 9/5 + 32) and rejects anything below absolute zero (0 K). That catches the classic bug of turning 0 °C into 0 °F.
Data sizes keep both ladders: KB/MB/GB/TB are SI decimal (1000-based, the way drive labels are sold) and KiB/MiB/GiB/TiB are IEC binary (1024-based, what many operating systems count). A “1 TB” drive showing ~931 GB is usually that mismatch, not a missing chunk of disk.
Data rate converts internet and transfer speeds. Broadband and Wi-Fi are sold in bits per second (Mbps, lower-case b), while browsers and game launchers show bytes per second (MB/s, capital B). One byte is 8 bits, so a 100 Mbps line tops out at 12.5 MB/s. Pick a speed and the download time box tells you how long a photo, film, game or backup takes, both at the full line speed and with a typical 10% lost to overhead. Background: Mbps vs MB/s explained.
Need the same maths from a script or CI job? Anvil's free unit converter API returns JSON with no key. Plain-words companions: KB vs KiB, C ↔ F ↔ K and metric tonne vs ton.
Questions
Is my number uploaded?
No. Conversion is pure JavaScript in your browser. Nothing is sent to a server.
Why is 1 KB not 1024 bytes?
In the SI standard used by drive makers, 1 KB = 1000 bytes. The binary unit for 1024 bytes is 1 KiB (kibibyte). This tool keeps both ladders so you can see the gap.
Why did 0 °C not become 0 °F?
Because temperature scales have different zeros. 0 °C is 32 °F. Converting only by multiplying (skipping the ±32 or Kelvin offset) is the classic bug.
Is t a US ton?
No. t is the metric tonne (exactly 1000 kg ≈ 2204.62 lb). A US short ton is 2000 lb; a UK long ton is 2240 lb. Convert those via pounds.
How many MB/s is 100 Mbps?
12.5 MB/s at most. Divide megabits per second by 8 to get megabytes per second. In practice expect roughly 11 to 11.8 MB/s after protocol overhead, and less on weak Wi-Fi.
How long does a 4 GB download take on 50 Mbps?
About 11 minutes at the full line speed (4,000,000,000 bytes × 8 ÷ 50,000,000 bits per second = 640 seconds), or about 12 minutes with typical overhead. Choose Data rate and use the download-time box for any size.
Can I convert pounds to kilometres?
No. Units must share a category. Mixing length and mass is rejected.
Is there an API?
Yes. Anvil's keyless /v1/units endpoint at api.oddlathe.com does the same conversions and returns JSON.