Behind the numbers
Guides
What each quantity means, how it is calculated, and where the figures that are not arithmetic actually come from. Every page supports specific calculators and carries its sources.
6 guides
Soil compaction, shrinkage and swell
Two different factors for the same soil, and published tables that disagree by tens of points. What FHWA, DOT and textbook tables actually say, the ±33% caveat, and the arithmetic.
Gravel driveway depth
No standard specifies a driveway. What the FHWA handbook and the Gravel Roads manual say for unpaved roads, why a driveway differs, and how any depth becomes yards and tons.
SupportsGravelCubic YardDirt Hauling
How cut and fill is calculated
The grid method step by step, the average-end-area and prismoidal formulas for cross-sections, and why area times average depth gets a balanced site wrong.
Dump truck capacity in cubic yards
Two limits decide how many yards a truck carries — the body volume on its plate and the payload its weight rating allows. The material decides which one binds.
SupportsDirt HaulingExcavationGravelDirt
Bank vs loose cubic yards
A bank yard is earth in the ground; a loose yard is the same earth in a truck, and there is more of it. Swell, load factor and the three volumes on one job.
Markup vs margin in construction
Markup is a percentage of cost, margin is a percentage of price. The conversion formulas, a worked example and the full table.