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Pounds to Kilograms Calculator

Convert pounds to kilograms for metric load ratings, payloads and material weights.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Weight

100 lb

High confidence

1 lb = 0.45359237 kg exactly, by the 1959 international agreement. Check whether a load figure is a working load limit or a breaking strength before relying on the converted value.

Conversion factor applied
1 lb per lb

Material weights, equipment payloads and load ratings all cross this boundary on internationally sourced work. The factor is exact by definition, so nothing is lost in the arithmetic. What deserves attention is what the number represents. Lifting and rigging figures are published as working load limits, which sit well below the breaking strength — commonly by a factor of five — and converting a breaking strength then treating it as a safe working figure is a safety failure that the units conversion will not flag. Structural work also distinguishes pounds-force from pounds-mass, where the former belongs in newtons rather than kilograms; general construction ignores the distinction because everything happens in the same gravity.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • International yard and pound agreement (1959): 1 lb = 0.45359237 kg exactly

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Is the conversion exact?
Yes. The pound has been defined as exactly 0.45359237 kilograms since 1959, so there is no measurement uncertainty here — only however many decimals you keep.
Working load or breaking strength?
Always check which a rating refers to before converting. Lifting and rigging equipment carries a working load limit well below its breaking strength, often by a factor of five, and treating one as the other is a serious safety error rather than a units problem.
What about pounds-force versus pounds-mass?
In everyday construction use they are treated interchangeably because we work in earth's gravity throughout. Structural engineering does distinguish them, and a figure in pounds-force converts to newtons rather than kilograms.