Doyle vs. Scribner vs. International (Log Scales)
Doyle, Scribner, and International are rules for estimating board-foot volume from logs, not interchangeable measurements. Doyle uses a common formula; Scribner and International require the applicable tables and scaling rules. Before comparing estimates or agreeing on payment, confirm the rule, table edition, measurement points, units, rounding, and deductions, then apply them consistently to every log.
A load can look unchanged from one scale to another, yet its estimated volume may shift enough to affect a sale. That is especially likely with small-diameter logs. I have seen how a scale name left out of a tally can turn a simple load check into a payment dispute. Clear measurements and an agreed rule prevent that.
Scaling-Rule Selection and Measurement Preparation
A log scale estimates the amount of lumber a log could yield, expressed in board feet. Doyle, Scribner, and International use different methods to make that estimate. Before measuring, find out which rule governs the sale or inventory, since the same log can receive different scale volumes under different rules.
Doyle, Scribner, and International are scaling conventions, not chainsaw or milling specifications. They do not tell you what equipment to use or how to cut. They address estimated recoverable lumber volume, and each reflects different assumptions about how a log might be sawn.
| Scale | How volume is determined | What to watch |
|---|---|---|
| Doyle | Common form: (D − 4)² × L ÷ 16 | Formula conventions, minimum diameter, and rounding |
| Scribner | Applicable Scribner table; Scribner Decimal C is a common variant | Table edition, length increments, and local scaling rules |
| International ¼-inch | Applicable International ¼-inch table | Table edition and prescribed measurements |
Here, D is small-end diameter in inches and L is log length in feet. These symbols describe a common Doyle formula; they do not replace local scaling instructions. Scribner and International should be read from the specified tables, not treated as formulas with one exact result for every jurisdiction.
The International ¼-inch scale models lumber recovery with a ¼-inch kerf allowance. In general, it accounts for taper and recovery more fully than Doyle or Scribner. That does not mean its number is automatically the right one for a sale: the contract and applicable rules decide which scale to use.
Which log scale should you use?
The right scale is the one named in the contract or required by the jurisdiction. A buyer and seller should not choose separate scales after seeing which gives a preferred result. Confirm the rule name and version before scaling, including whether “Scribner” means a specified table or Scribner Decimal C.
When no sale contract applies, choose a recognized rule that fits the intended estimate, then state it in your records. A scale is an estimate, not a direct measurement of finished lumber. Actual recovery can vary with log shape, defects, saw kerf, and how the log is sawn.
Takeaway: Agree on the scale before tallying; do not compare bare board-foot totals without the rule behind them.
Field Log Measurement and Volume Calculation
A scale result depends on how the log is measured as well as on the rule used. Diameter, length, bark, taper, and rounding can all affect the result. Use the measurement point and method set by the governing rule, then apply one consistent procedure to the full load.
A common basis is small-end diameter inside bark, but measurement rules are not universal. The authority or contract may specify how to handle bark, sweep, trim, and rounding. Do not assume that one buyer’s method applies to another sale.
- Check the instructions. Confirm the scaling point, accepted length increments, minimum log length and diameter, and any defect policy.
- Inspect the ends. Clear loose debris so you can identify the end and take a sound measurement. Remove bark only if the rules permit it.
- Measure at the required point. Use a suitable diameter tape or scale stick, and follow the rule’s instructions for irregular ends or more than one diameter reading.
- Measure log length. Use the prescribed method and unit. Check whether trim allowance or a required length increment changes the scaled length.
- Record the measurements. Keep diameter, length, rule, and any deductions with that log’s tally.
For Doyle, the common formula is BF = (D − 4)² × L ÷ 16. As an arithmetic example, a log measured at 12 inches and 16 feet gives (12 − 4)² × 16 ÷ 16, or 64 board feet under that formula before any rule-specific adjustments. This is an illustration, not a universal sale scale: rounding, minimum diameters, and other local provisions may change the accepted result.
For a diameter of 8 inches and length of 16 feet, the same arithmetic gives 16 board feet. The example shows how the formula responds to diameter; it does not establish what Scribner or International would return for that log. Use their applicable tables for those results.
Why small logs can create a large difference
Doyle’s common formula subtracts four inches from the diameter before squaring it. As a result, small-diameter logs can receive substantially lower estimates under Doyle than under Scribner or International. Where the diameter is at or below four inches, do not use the arithmetic alone to decide the scale result; follow the governing rule’s minimum-diameter provisions.
A small-log load can therefore look much different when someone changes scales mid-tally. That does not by itself prove that either tally is wrong. It means the rule and its measurement conventions need to be identified before the numbers can be compared.
Takeaway: Measure by the agreed method first, and apply the appropriate formula or table only after the dimensions are set.
Scale Verification, Tables, and Recordkeeping
A checkable tally ties each result to its measurements and scaling rule. For Doyle, preserve the inputs and permitted adjustments. For Scribner and International, record the table or edition used. This gives both parties a way to retrace the calculation instead of debating totals with no shared basis.
Do not substitute an online calculator or a remembered table for the governing source unless it matches the required rule, edition, units, and conventions. Scribner table editions and log-length increments can matter. International table results also depend on the applicable table and measurement instructions.
A useful log record includes:
- Log number or clear identifying mark
- Small-end diameter and measurement basis
- Length and unit
- Scale name, variant, and table edition when applicable
- Rounding method and any authorized deductions
- Result in board feet
| Check | What to verify | Why it matters |
|---|---|---|
| Rule | Doyle, Scribner variant, or International ¼-inch | Different rules can yield different totals |
| Table or method | Applicable edition or authorized formula | Prevents mismatched references |
| Units | Inches and feet, or units required by the rule | A unit error changes the result |
| Measurement basis | End, bark treatment, and length method | Measurements must be comparable |
| Adjustments | Rounding, sweep, trim, and defects | Deductions must follow agreed rules |
For a lot, total the individual log results only after each log has been scaled under the same agreed procedure. If a log is disputed, review its recorded dimensions and applicable table entry or formula. Do not switch scales on that log alone to make the total match another tally.
Illustrative field checks
These examples describe common scaling situations; they are not records of actual sales or universal results.
- Small-diameter load: A tally is much lower when someone applies Doyle instead of Scribner. First confirm the scale named in the contract. Then check diameter measurements, minimum-diameter rules, and any table variant before treating the difference as an error.
- Different length increments: Two Scribner tallies disagree even though the diameters look similar. Check the table edition and permitted log-length increments. A mismatch in those settings can explain why the same nominal log does not receive the same scale.
- Bark or rounding disagreement: The parties agree on the scale name but not on the diameter. Check whether the governing rules require inside-bark measurement, how diameter is rounded, and whether bark may be removed. Resolve the measurement basis before recalculating.
Takeaway: A useful audit trail records enough detail for someone else to repeat the scale, not just the final total.
Contract Documentation and Dispute Prevention
A scale dispute is harder to resolve when the agreement names only “board feet” or “Scribner” without further detail. Document the rule and measurement practices before the load is tallied. If the sale is governed by local scaling rules, confirm those requirements rather than relying on an informal agreement that conflicts with them.
Write down the details that affect the result:
- Rule name and variant, including the specified Scribner or International table edition
- Units and measurement point, including bark treatment
- Accepted length increments and any minimum lengths or diameters
- Rounding method and authorized trim, sweep, or defect deductions
- How both parties can review the tally and challenge a disputed log
Before scaling begins, compare the written instructions with the field tally sheet. If a rule is unclear, ask the buyer, seller, or relevant scaling authority to clarify it before measuring. A short pause at the start is easier to manage than re-scaling a completed load.
If a dispute occurs, keep the original dimensions and tally. Identify the specific logs at issue, verify the rule and table edition, and repeat the calculation using the documented conventions. Do not change rules or deductions partway through the lot unless both parties explicitly agree and record the change.
Takeaway: Put the scaling method in writing and make the records detailed enough to reproduce the result.
Conclusion and FAQ
The practical difference among these log scales is how they estimate recoverable board-foot volume. Doyle uses a common formula, while Scribner and International rely on their applicable tables and local conventions. Their results are not automatically interchangeable. Measurement practices matter just as much as the scale name.
To make a sound comparison, identify the governing rule, verify the measurement basis, and record each log’s dimensions and result. For a payment or contract question, compare tallies only when the rule, edition, units, rounding, and deductions match.
What is the main difference between Doyle, Scribner, and International?
They are different log-scaling methods for estimating board-foot volume. Doyle commonly uses a formula; Scribner and International use the applicable tables.
Which log scale gives the most board feet?
There is no single answer for every log. Results depend on log dimensions, scale, table edition, and measurement rules.
Why does Doyle often scale small logs lower?
The common Doyle formula subtracts four inches from the diameter before squaring it. That feature can lower estimates for small-diameter logs compared with Scribner or International.
Is Scribner Decimal C the same as every Scribner scale?
No. Scribner Decimal C is a commonly used variant, but the required table and local scaling rules still matter.
Can I calculate Scribner with one exact formula?
Do not rely on one universal formula. Use the applicable Scribner table and follow its edition, length increments, and scaling rules.
What does the ¼-inch mean in International ¼-inch?
It refers to the scale’s allowance for a ¼-inch saw kerf in its lumber-recovery model.
Where should I measure a log’s diameter?
Follow the governing rule. A common basis is the small end inside bark, but the prescribed point and bark treatment can vary.
Can I compare two scale totals directly?
Only if the totals use the same rule, table edition, units, measurement basis, rounding, and deductions. Otherwise, the comparison may not be valid.
What should I record for each scaled log?
Record its identifier, diameter, length, scale and edition, adjustments, and board-foot result. This lets another person check the tally.
What should I do if buyer and seller tallies disagree?
Check the contract and scaling rules, then review the disputed logs’ measurements and calculations under that same rule. Do not switch scales mid-lot to force a match.
(This article was written by one of our staff writers, Samuel Vance. Visit our Meet the Team page.)
