Vriksai Timber Intelligence

Log Taper CalculatorDiameter Change and Form Factor Analysis

Calculate log taper rate, IS 1902 taper class, form factor, and volume loss due to taper. Essential for quality grading, sawmill yield planning and purchase price negotiation.

IS 1902 Taper ClassesForm FactorVolume Loss %Price Impact INRPDF Report

Log Taper Calculator

Diameter Change and Form Factor Analysis

Unit System and Species

Unit System

Wood Species

Price per m3

INR/m3

Diameter Measurements

Large-End Diameter (butt)

Small-End Diameter (top)

Log Length

metres

Mid-Point Diameter (optional)

Leave 0 to auto-calculate as average of two ends.

Number of Logs

logs

IS 1902 Classes:
Class 1: <=0.5 cm/m (slight)
Class 2: 0.5-1.5 cm/m (moderate)
Class 3: >1.5 cm/m (excessive)

Taper Analysis Results

cm/m

Taper Rate

form factor

Form Factor f

IS 1902

Taper Class

Volume Loss vs Cylinder

Measurement	Value	Method	Note

Taper Analysis

About Log Taper Calculator

Taper is the reduction in diameter from butt to top end of a log. High taper reduces sawmill yield, causes skewed boards, and lowers log grade and price. IS 1902:2015 India classifies taper into three grades for pricing purposes.

Where Used?

Log Grading IS 1902Sawmill Yield PlanningTimber PurchaseForest Dept IndiaImport Quality Control

Formulas

Taper = (D_large - D_small) / L cm per metreForm factor f = V_huber / V_cylinderIS 1902 Class 1: taper <= 0.5 cm/m (slight)IS 1902 Class 2: 0.5 to 1.5 cm/m (moderate)IS 1902 Class 3: > 1.5 cm/m (excessive)

FAQ

How does taper affect sawmill yield?

A log with 2 cm/m taper and 5m length loses roughly 18-25% of sawn lumber vs a uniform cylinder. Tapered logs require offset cuts, wasted edging, and irregular board widths. Mills pay 5-15% less per m3 for Class 3 logs.

Log Taper CalculatorDiameter Change and Form Factor Analysis

Log Taper Calculator

About Log Taper Calculator

Where Used?

Formulas

FAQ

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