Evaluate lumber quality and determine grades based on NHLA standards. Assess defects, appearance, and structural characteristics to classify hardwood and softwood lumber grades accurately.
Enter lumber characteristics and click "Calculate Grade" to see the assessment results.
The National Hardwood Lumber Association (NHLA) establishes the grading standards used throughout North America for hardwood lumber. These standards provide a consistent framework for evaluating lumber quality based on the percentage of clear, usable wood in each board.
Clear Face % = (Clear Cuttings Area / Total Board Area) x 100 | Grade | Clear Face % | Min Width | Min Length | Typical Price Premium |
|---|---|---|---|---|
| FAS | 83.3%+ | 6" | 8' | 100% (baseline) |
| FAS 1-Face | 83.3% / 66.7% | 6" | 8' | 90-95% |
| Select | 83.3%+ | 4" | 6' | 85-90% |
| #1 Common | 66.7%+ | 3" | 4' | 65-75% |
| #2 Common | 50.0%+ | 3" | 4' | 45-55% |
| #3 Common | 33.3%+ | 3" | 4' | 25-35% |
FAS requires 6" minimum width and 8' minimum length. Select maintains the same 83.3% clear requirement but allows 4" wide by 6' long boards. Choose Select when your project uses smaller components — you get the same quality at lower cost with more flexible dimensions.
Lumber defects significantly impact grading and must be carefully evaluated. Understanding these defects helps you select appropriate grades and anticipate yield from each board.
| Defect Type | Minor Impact | Moderate Impact | Severe Impact |
|---|---|---|---|
| Knots | Pin knots only, few | Small-medium, scattered | Large, numerous, loose |
| Checks/Splits | Surface checks only | Moderate checks | Through splits |
| Warp (Bow/Cup/Twist) | < 1/8" deviation | 1/8" - 1/4" | > 1/4" deviation |
| Sapwood | < 10% of face | 10-30% of face | > 30% of face |
| Staining | Light mineral streak | Moderate discoloration | Dark stain/fungal |
| Grain | Straight | Interlocked | Irregular/cross grain |
Choosing the appropriate lumber grade balances quality requirements against cost considerations. Understanding typical applications for each grade helps optimize your material budget.
Use premium grades for visible surfaces and lower grades for hidden components:
Savings example: A $2,000 FAS-only project could cost $1,300-$1,500 with strategic mixed-grade purchasing — 25-35% savings.
Accurate lumber grading requires understanding NHLA rules and developing a practiced eye for evaluating boards.
The highest NHLA hardwood grade. Requires 83.3%+ clear face cuttings with minimum board dimensions of 6" wide by 8' long. Used for fine furniture and premium cabinetry.
A rectangular area on a board surface that is free of defects (knots, checks, wane, etc.). Clear cuttings must meet minimum size requirements specific to each grade level.
National Hardwood Lumber Association — the organization that establishes and maintains hardwood lumber grading standards used throughout North America.
A defect formed where a branch grew from the tree trunk. Sound (tight) knots are solid and remain in place; loose knots may fall out during processing. Knot size directly impacts grade classification.
A surface crack or separation in wood fibers, typically caused by uneven drying. Distinguished from splits, which extend through the full thickness of the board.
Distortion in lumber from its flat plane. Includes bow (lengthwise curve), cup (width-wise curve), twist (spiral distortion), and crook (edgewise curve). Severity measured in deviation per length.
The lighter-colored, outer portion of the tree between the bark and heartwood. While structurally sound, it is less durable and may be considered a defect for appearance-grade applications.
The presence of bark or missing wood along the edge of a board. Reduces the usable width and requires additional trimming. Considered a defect in all NHLA grades.
Both FAS and Select require 83.3% clear face. The key difference is minimum dimensions: FAS requires 6" wide x 8' long, while Select allows 4" wide x 6' long. Select offers the same quality in smaller boards at slightly lower cost.
Visualize the largest rectangular clear cuttings you can extract from the board face. Calculate: Total clear cutting area / Total board surface area x 100. Each cutting must meet minimum size for that grade.
Yes — hardwoods use NHLA standards (FAS, Select, Common). Softwoods use WWPA or SPIB standards with different grade names (Select Structural, #1-#3, Construction, Standard, Utility). The grading criteria differ significantly.
Pin knots (<1/4") have minimal impact. Sound knots (tight, solid) are considered defects but less severe than loose knots (may fall out). Large, numerous knots significantly reduce clear-face percentage and lower the grade.
Yes — figured grain like curly maple or bird's eye is NOT considered a defect. In fact, heavily figured boards often command premium prices above standard FAS pricing due to their decorative value and rarity.
Approximate pricing relative to FAS: Select (85-90%), #1 Common (65-75%), #2 Common (45-55%), #3 Common (25-35%). Using mixed grades strategically can save 25-35% on total project material costs.
It depends on your project. #1 Common is often the best value for furniture — it yields enough clear cuttings for most components at 25-35% less cost. Use FAS only for wide, long components like tabletops where you need maximum clear yield.
NHLA standards assume lumber is dried to 6-8% MC. Green (wet) lumber may appear to have fewer defects, but checks and warping often become apparent after drying. Always verify MC before final grading. Use our moisture content calculator for accurate measurements.