From this site

One project, every trade

Each calculator adds its lines to a single estimate — consolidated BOM, schedule and cash-flow included.

Open My Project →

Structural Material Carbon Comparison Calculator

Compare the cradle-to-gate carbon of two structural options on the same job, per unit of mass.

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 2026-08-27 · v1.1.0

Market
Imperial · sales tax

Carbon difference

11280 kgCO₂e

Low confidence

Emission factors here are typical published ranges for orientation, not product data. A reportable assessment uses the supplier's own Environmental Product Declaration — the spread between two suppliers of the same nominal product routinely exceeds 30%.

Option A total
23880 kgCO₂e
Option B total
12600 kgCO₂e
Lower option
2 (B is lower)
Difference in tonnes
11.28 tCO₂e
B as a percentage of A
52.76 %

For the dimensions entered, expect a carbon difference of 11280 kgCO₂e. Of the working steps, option a total dominates at 23880 kgCO₂e. Note that option a — mass and option a — factor (kgco₂e/kg) sit at the edge of the range this calculator was checked against, so treat the output as indicative rather than settled. The confidence rating here is low. Get the figure confirmed by a supplier or a qualified trade before committing to it. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Add the equipment this sizes

This result is a specification — 11,280 kgCO₂e — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

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

  • EN 15804 A1-A3 cradle-to-gate boundary applied consistently to both options
  • Biogenic carbon in timber is reported separately under EN 15804+A2 and is not netted off the fossil figure here

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 timber automatically lower carbon than steel?
Not automatically, and the comparison is easy to rig. Timber's factor per kilogram is far lower, but a timber solution may need considerably more mass, deeper sections, and additional fire protection to do the same job. The honest comparison is between two designs that both satisfy the same brief — same span, same loading, same fire rating — not between two lumps of material.
Why is stored biogenic carbon left out?
Because whether it may be counted depends entirely on what happens at end of life, and that is an assumption rather than a measurement. Timber that is reused or kept in service holds its carbon; timber that is burned or landfilled releases it. Netting the storage off the fossil figure without stating the end-of-life assumption is one of the most common ways a comparison is made to say what its author wanted.
Does cradle-to-gate tell the whole story?
No, and on close results it can mislead. Modules A1-A3 stop at the factory gate — they exclude transport to site, erection, maintenance over the service life, and demolition. A material with a modestly higher gate figure but a much longer service life or a genuine reuse route can be the lower-carbon choice over the building's life.