---
title: "Hoppus Volume Calculator (Quarter-Girth Rule)"
description: "Calculate Hoppus volume, true volume and Hoppus tons for round logs — free."
image: "https://nestingcalc.com/og-default.png"
url: "https://nestingcalc.com/hoppus-calculator/"
locale: "en"
---

# Hoppus Volume Calculator (Quarter-Girth Rule)

Calculate Hoppus volume, true volume and Hoppus tons for round logs — free.

Enter mid-length circumference and log length. The calculator applies the quarter-girth (Hoppus) formula used in the hardwood trade, converts to true volume, Hoppus tons and board feet, and values a whole stack with quantity and price.

Interactive calculator (open in browser): [https://nestingcalc.com/hoppus-calculator/](https://nestingcalc.com/hoppus-calculator/)

## FAQ

What is the Hoppus rule?

The Hoppus (quarter-girth) rule estimates round timber volume from the circumference at mid-length: (C ÷ 4)² × L. It is the standard trade measure for tropical hardwoods and assumes about 78.5% of the true cylindrical volume — the recovery after sawing loss.

How do I convert Hoppus volume to true cubic metres?

Multiply the Hoppus figure by 4 ÷ π ≈ 1.2732. One Hoppus cubic metre (h m³) equals about 1.2732 true m³, and 1 h ft³ ≈ 0.03605 m³.

What is a Hoppus ton?

A Hoppus ton (HT) is 50 Hoppus cubic feet ≈ 1.8027 true m³ — a traditional shipping unit for tropical logs.

Why is Hoppus volume less than true volume?

The quarter-girth rule divides the circumference by 4 instead of by π, which quietly multiplies the result by π/4 ≈ 0.785. The shortfall is a built-in allowance for sawing losses — multiply Hoppus by 1.273 to approximate true content.

Where exactly do I measure the girth?

Mid-length of the log, under bark, with the tape snug. On oval logs take both axes and average them — the rule assumes a cylinder, and honest averaging is what keeps it accurate.

How many board feet is a Hoppus foot?

Trade convention says ≈ 10 board feet per Hoppus cubic foot; pure geometry says ≈ 12.7. The 10 BF figure is the historic nod to sawmill losses — use the one your contract uses, and never switch mid-deal.

Is Hoppus still used for teak?

Yes — plantation teak in India, Myanmar and parts of Africa and Latin America is still contracted in Hoppus feet or Hoppus tons. It persists wherever the paperwork and the money have always spoken Hoppus.

Hoppus vs JAS — which gives more volume?

It depends: Hoppus reads from mid-length girth, JAS from the rounded-down small end with a taper add-on — taper, shape and rounding push the answer either way. The practical rule is consistency: one scale per contract, reconciled through true cubic metres when needed.

Can I convert a Hoppus price to a price per true cubic metre?

Divide by 1.273: a price of 60 per Hoppus m³ equals about 47 per true m³, because one Hoppus cubic metre corresponds to 1.273 true cubic metres of wood — the same log simply carries a smaller number in Hoppus units, so the unit price must shrink with it.

Does Hoppus work in metric?

Yes — girth in centimetres and length in metres: h m³ = (C/4)² × L ÷ 10,000. The 4/π bias is identical in both systems; only the arithmetic changes.

How accurate is Hoppus on butt logs?

Measure above the root flare — flare at mid-length inflates the girth and the cube. With heavy taper, Hoppus tends to underestimate true content; consistent measurement height matters more than which height you pick.

Can I use Hoppus for sawn lumber?

No — Hoppus is a roundwood rule. Sawn lumber trades in board feet, cubic metres or cunits; the timber-unit converter translates between all of them, and Hoppus drops out of the picture once the first saw cut is made.

## Related calculators

-   [Log Volume Calculator (Huber, Smalian, Newton)](https://nestingcalc.com/log-volume-calculator/)

    Estimate the cubic volume of a log with Huber, Smalian or Newton — free.

-   [JAS Log Scale Calculator (Japanese Agricultural Standard)](https://nestingcalc.com/jas-log-scale-calculator/)

    Scale logs to the JAS rule with diameter rounding and ovality — free.

-   [Timber Unit Converter (m³, BF, MBF, Hoppus)](https://nestingcalc.com/timber-unit-converter/)

    Convert between cubic metres, board feet, Hoppus units and prices — free.

-   [Green Log Weight Calculator](https://nestingcalc.com/log-weight-calculator/)

    Weight of round timber at any moisture content, by species — Wood Handbook 2021 data.

## Related guides

-   [Hoppus Formula Explained: Quarter-Girth Log Measurement](https://nestingcalc.com/guides/hoppus-formula-explained/)

    The Hoppus (quarter-girth) formula h = (C/4)² × L/144, why it reads about 78.5% of true volume, Hoppus tons, and worked examples in imperial and metric.

-   [How to Calculate Board Feet (and Log Scaling Rules)](https://nestingcalc.com/guides/how-to-calculate-board-feet/)

    The board foot is how lumber is bought and sold. The formula takes a minute; the scaling rules and pricing traps take a bit more.

-   [The Material Order Checklist: Before You Buy Steel, Wood or Tile](https://nestingcalc.com/guides/material-order-checklist/)

    Ten minutes of checking before the order saves a second trip to the supplier.

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