Grit Classifications (CAMI Standard)
CAMI (Coated Abrasive Manufacturers Institute) is the most common grading system in North America. Grit numbers indicate particles per linear inch — lower number = coarser grit.
Last updated: 2026-02-27
Sandpaper Requirement Calculator
Professional sanding calculator for woodworking projects. Calculate grit progression, sheet quantities, disc requirements, and belt sanding needs with surface area analysis and cost estimation.
Grit Progression Surface Analysis Cost Calculator Time Estimation
Project Specifications
Surface to Sand
Wood & Project Details
Sandpaper Specifications
%
Additional Surfaces
Cost Analysis
$ per sheet
$ per project
Sanding Results
Enter surface dimensions and sanding specifications to calculate your sandpaper requirements and grit progression plan.
Sanding operations require proper dust collection, respiratory protection (N95 minimum), and eye protection. Wood dust is classified as a Group 1 carcinogen by WHO/IARC. Always ensure adequate ventilation.
Never skip more than one grit level. Each grit should remove scratches from the previous grit. Skipping creates deep scratches that finer grits cannot efficiently remove.
How to Use This Calculator
- 1 Enter Surface Dimensions Input length and width of the surface to sand. Select units and number of surfaces.
- 2 Set Wood & Project Details Choose wood species, current condition, desired finish quality, and sanding method.
- 3 Select Sandpaper Type Choose abrasive material (aluminum oxide, ceramic, garnet, etc.) and waste percentage.
- 4 Add Cost Info Enter sandpaper cost per sheet and supply cost for budget estimation.
- 5 Review Results Get grit progression plan, sheet quantities per grit, total cost, and estimated time.
Pro Tip: Golden Rule: Never skip more than one grit level. Standard furniture progression: 80 → 120 → 180 → 220. Each grit removes scratches from the previous grit. Use a raking light (low angle) to check for remaining scratches before moving to the next grit.
| Grade | Grit Range | Purpose | Common Use |
|---|---|---|---|
| Coarse | 40-60 | Heavy removal, rough shaping | Removing mill marks, paint stripping |
| Medium | 80-120 | Primary sanding, most versatile | Furniture making, planer mark removal |
| Fine | 150-180 | Pre-finish sanding | Standard for hardwoods before finish |
| Very Fine | 220-320 | Final sanding, between coats | Pre-finish, between coat scuffing |
| Ultra Fine | 400+ | Finish polishing | Wet-sanding finishes, polishing clear coats |
FEPA (European) uses P-prefix (P40 ~ 40 CAMI). Micron system measures actual particle size.
Abrasive Materials
Different abrasive materials suit different applications. Material choice affects cost, longevity, and surface quality.
| Material | Coverage/Sheet | Cost/Sheet | Best For | Lifespan |
|---|---|---|---|---|
| Aluminum Oxide | 8-15 sq ft | $1.50-$3.50 | All-purpose, hardwoods | Medium |
| Ceramic | 40-75 sq ft | $4-$8 | Very hard woods, heavy removal | 3-5x longer |
| Silicon Carbide | Variable | $2-$4 | Finish sanding, wet sanding | Short on wood |
| Garnet | 5-10 sq ft | $1-$2.50 | Hand sanding, final passes | Short (natural) |
| Zirconia Alumina | 20-40 sq ft | $3-$6 | Belt sanders, production | 2-3x longer |
Coverage varies by wood hardness, grit coarseness, and sanding pressure.
Grit Progression Strategy
Golden Rule: Never skip more than one grit level. Each grit should remove scratches from the previous grit. Skipping grits wastes time and sandpaper.
Standard Grit Progressions
- Rough Lumber: 60 → 80 → 120 → 150 → 180 → 220
- Planed Lumber: 80 → 120 → 180 → 220 (most common)
- Pre-Sanded Plywood: 150 → 180 → 220 (light sanding only)
- Between Finish Coats: 220 → 320 or 400 (light scuff)
Wood Species Adjustments
- Softwoods (Pine, Cedar): Start 100, stop at 180-220. Higher grits close pores and impair stain absorption
- Medium Hardwoods (Cherry, Walnut): Standard 80 → 120 → 180 → 220. Cherry benefits from 220 minimum to reduce blotching
- Hard Hardwoods (Oak, Maple): Can start 60, finish 220-320 for glass-smooth
- Exotic Woods: More steps needed, use ceramic abrasive for best results
Sanding Methods & Coverage
Different sanding methods have dramatically different coverage rates and are suited for different stages of the sanding process.
| Method | Coverage/Sheet | Speed | Best For |
|---|---|---|---|
| Hand Sanding | 8-12 sq ft | ~20-30 min/sq ft/grit | Detail work, final sanding, edges |
| Random Orbital Sander | 15-25 sq ft/disc | ~5-10 min/sq ft/grit | General furniture, no swirl marks |
| Belt Sander | 30-50 sq ft/belt | ~2-5 min/sq ft | Heavy removal, flattening, production |
| Detail/Palm Sander | 10-15 sq ft/1/4 sheet | ~15-20 min/sq ft/grit | Tight areas, edges, small projects |
| Drum Sander | 100+ sq ft/roll | ~1-2 min/sq ft | Dimensional sanding, wide boards |
Coverage varies by wood hardness, grit, and sanding pressure. Belt sander not recommended for finish sanding.
Wood Species Tips
Sanding difficulty varies significantly by species
Sanding Best Practices
- Always sand with grain for final passes — cross-grain scratches show through finish
- Use a sanding block for flat surfaces — prevents finger grooves
- Change paper when it stops cutting efficiently — dull paper creates heat
- Use raking light (low angle) to check for scratches between grits
- Vacuum between grits — coarse particles left behind will scratch
- Let the sander do the work — heavy pressure creates heat and uneven sanding
Example: Sanding a Dining Table Top (48" x 36", Oak)
- Surface: 48 x 36 inches = 12 sq ft, planed oak (hardwood)
- Progression: 80 → 120 → 180 → 220 (4 grits)
- Method: Random orbital sander (5-inch disc)
- Discs needed: 12 sq ft / 20 sq ft per disc x 1.2 waste = about 1 disc per grit, 4 discs total
- Time estimate: 12 sq ft x 7 min per sq ft per grit x 4 grits = about 5.5 hours
- Cost: 4 discs at $1.50 each = $6.00 + supplies
Glossary of Terms
Coated Abrasive Manufacturers Institute — the primary grit grading system used in North America. Grit number = particles per linear inch. Lower number = coarser.
The sequence of grits used from coarse to fine. Each grit removes scratches from the previous one. Standard furniture: 80 → 120 → 180 → 220.
Most common abrasive for woodworking. Brown/reddish color. Self-fracturing (creates fresh cutting edges as it wears). Good all-purpose choice.
Premium abrasive that lasts 3-5x longer than aluminum oxide. Blue/purple tint. Self-sharpening. Best for very hard woods and heavy removal.
Sandpaper with 50-70% abrasive coverage. Resists clogging better than closed coat. Best for resinous woods (cherry, pine) and softwoods.
Sandpaper with 100% abrasive coverage. Cuts faster but clogs quicker. Best for hardwoods and flat surfaces.
Amount of material removed per abrasive particle per pass. Affected by pressure, speed, and grit size. Optimal chip load prevents heat buildup.
A light held at a very low angle (nearly parallel to surface) to reveal scratches, dips, and imperfections invisible under normal lighting. Essential quality check between grits.
Frequently Asked Questions
How do I calculate sandpaper requirements for my project?
Calculate total surface area to sand, determine grit progression based on current condition and desired finish, estimate sheets per grit based on surface area and sanding method, then add 20-30% for waste. Our calculator automates this entire process.
What grit progression should I use for furniture making?
For furniture from planed lumber: 80 → 120 → 180 → 220. For rough lumber, start at 60. For fine finishes, continue to 320. Never skip more than one grit level.
How much sandpaper do I need per square foot?
Hand sanding: 1 sheet per 8-12 sq ft per grit. Orbital sander: 1 disc per 15-25 sq ft. Belt sander: 1 belt per 30-50 sq ft. Actual usage depends on wood species, condition, and desired finish.
What's the difference between sandpaper types?
Aluminum oxide: versatile, all woods. Ceramic: longest lasting, hard woods. Silicon carbide: finish sanding, wet sanding. Garnet: traditional hand sanding, great stain prep. Zirconia: heavy-duty production belts.
How do I know when to change to the next grit?
Change grits when all scratches from the previous grit are removed and the surface has a uniform scratch pattern. Use raking light (low angle) to check. Total sanding time should be roughly equal at each grit.
What safety precautions should I take when sanding?
Always use dust collection or work outdoors. Wear N95 or better respiratory protection — wood dust is a proven carcinogen (WHO Group 1). Safety glasses and hearing protection for power sanders. Some species (cedar, walnut, rosewood) cause allergic reactions.