How to calculate sawmill yield (log recovery vs multi-rip yield) – formulas + example

If you want to improve yield, you first need to measure it consistently. Most “yield confusion” comes from mixing different definitions: one week you count from logs, the next week you count from the multi-rip infeed, and then you compare numbers that are not comparable.

This post gives you a practical set of yield metrics (in m³), simple formulas, and a measurement checklist.

1) Three yield definitions you should separate

A) Log recovery (from logs to sawn timber)

Answers: how many m³ of lumber you get from m³ of logs.

Formula: Log recovery [%] = (m³ lumber / m³ logs) × 100

Use it to track upstream performance: sawing pattern, log breakdown, edging decisions, grading, trim losses.

B) Multi-rip / edging stage yield (from infeed boards to finished widths)

Answers: how many m³ of product you get from m³ entering the multi-rip stage.

Formula: Stage yield [%] = (m³ product after multi-rip / m³ boards at infeed) × 100

This metric reacts quickly to:

• random board offset/angle at infeed,
• wane waste,
• kerf across multiple cuts,
• feed stability and guides.

C) Sales/grade yield (what you can actually sell)

Answers: how much sellable A/B volume you get from your input.

Example formula: Sales yield [%] = (m³ sold A+B / m³ input) × 100

This is the most business-relevant number because it includes quality, rework, and claims.

2) Example: same week, different conclusions

Assume one week:

• input: 100 m³ logs
• after breakdown: 55 m³ unedged boards
• after multi-rip: 48 m³ product

Then:

• log recovery = 55 / 100 = 55%
• multi-rip stage yield = 48 / 55 = 87.3%
• overall log → product = 48 / 100 = 48%

If variation is mostly in stage yield, your biggest lever is often the last meters before the multi-rip (infeed reference, offset/angle, wane strategy), not the logs.

3) How to measure yield on a real line (checklist)

1. Pick a time window: shift, day, week, or one product run.
2. Pick one unit: m³ is the simplest for EU reporting; use it consistently.
3. Define “input m³”:
   • purchased logs volume,
   • measured log volume,
   • unedged board volume at multi-rip infeed,
   • dried/planed output volume.
4. Decide: nominal vs actual dimensions:
   • nominal is easier for reporting,
   • actual dimensions reveal process losses,
   • choose one approach and don’t mix.
5. Split by product class: thickness, target width set, species, moisture state.
6. Capture reasons for deviations (short notes): “blade change”, “guide wear”, “extraction issue”, “operator change”.

Minimum spreadsheet that works:

• date/shift,
• input m³ (with definition),
• output m³ (with definition),
• yield %,
• thickness/target widths,
• notes.

4) The most common yield calculation mistakes

• Mixing log recovery and multi-rip stage yield into one number.
• Comparing weeks with different thickness or product mix.
• Ignoring trim and rework (it’s real volume).
• Tracking “produced” but not “sellable” (quality can destroy the business result).

5) What to do with the numbers

If your multi-rip yield swings by shift or operator, a common root cause is random infeed reference: boards enter shifted or skewed, so the same saw spacing produces different waste.

See how an automatic board positioning module stabilizes offset/angle and improves repeatability: /blog/board-centering-before-multi-rip-saw/.
If you want a practical “what to fix first” checklist, read: /blog/how-to-increase-sawmill-yield/.
If you want to calculate ROI on your line using your own input/output data, contact us: /contact/.