How we calculate

We never invent a price

This is the rule that shapes the whole platform. No Calcumetryx calculator contains a market rate, an industry average, or a “typical cost per cubic yard”. Every price field starts empty and stays empty until you fill it.

Construction pricing is local, seasonal and job-specific. A number that looks authoritative but came from nowhere is worse than no number at all, because you might build a budget on it. So our cost tools do all the work that is genuinely deterministic — geometry, unit conversion, swell, load counts, overhead, markup versus margin — and then stop and ask you for the one thing only you can know.

Unit conversions are exact, not approximate

All conversions use definitional values, not rounded ones: one inch is exactly 25.4 millimetres, one US short ton is exactly 2,000 pounds, one acre is exactly 43,560 square feet, one cubic yard is exactly 27 cubic feet. Everything you type is converted into a single base unit before any formula runs, which is why you can enter a length in metres, a width in feet and a depth in inches in the same calculation.

The working is on the page

Each result shows the symbolic formula, the same expression with your numbers substituted in, and the value of every step. You should never have to trust a black box. If our answer differs from yours, the working shows you exactly which line you disagree with.

We use the exact geometry, not the convenient one

• Excavations with battered walls use the prismoidal formula, V = d/6 × (A_base + 4·A_mid + A_top). Averaging the top and base areas — the common shortcut — overstates the volume.
• Circular excavations with sloped sides use the exact truncated-cone volume rather than an average-diameter cylinder.
• Trench cross-sections are trapezoids: d × (w + s·d), derived from the bottom width, the top width and the depth.
• Truck loads are the greater of the volume limit and the weight limit, rounded up. A part load is still a trip.

Soil behaviour is yours to supply

Swell factors, in-situ densities and loose densities are properties of your material, not constants we can look up for you. They vary with soil type, moisture and handling. Every one of those fields is optional and blank by default, and the calculator tells you what it cannot work out without them rather than filling the gap with a guess.

External data carries its paperwork

If any Calcumetryx calculator ever uses a number that did not come from you and is not a definitional unit conversion, it must carry a full record: the organisation, the dataset, a link, the geography it covers, the period, the unit, how we transformed it, its limitations, and the date we last verified it. That record is shown on the calculator page.

Right now, no calculator on this site uses any external data at all. Every tool runs purely on your inputs and exact conversions.

Formulas are versioned and dated

Every calculator shows a formula version and a last-reviewed date. If we change how something is computed, the version changes, so a result you printed six months ago can be traced back to the method that produced it.

What we do not do

• We do not give engineering, safety or financial advice.
• We do not determine trench safety requirements. Sloping, benching and shoring are decisions for the competent person on your site.
• We do not replace a survey, a geotechnical report or a written quote.
• We do not publish keyword variations of the same tool. If two calculators would do the same arithmetic, we merge them.

Think something here is wrong? Tell us — corrections to the maths go to the front of the queue.