Plank Make converts logs at 70 per cent of the sawmill fee, but the runes cost more than that saving at current prices, which makes the sawmill the cheapest option for every plank tier. Buying finished planks costs the most gold and the least time.
This article compares all three routes with the rune cost included, using Grand Exchange prices checked on 25 August 2026.
What Plank Make actually is
Plank Make is a Lunar spell that converts one log into a plank of the same type. Its requirements are fixed:
| Requirement | Detail |
|---|---|
| Magic level | 86 |
| Spellbook | Lunar |
| Quest | Dream Mentor |
| Runes per cast | 2 astral, 1 nature, 15 earth |
| Magic experience | 90 per cast |
| Cast speed | 3 ticks manual, 6 on autocast |
The conversion cost is 70 per cent of what the sawmill operator charges:
| Plank | Sawmill fee | Plank Make fee |
|---|---|---|
| Plank | 100 gp | 70 gp |
| Oak plank | 250 gp | 175 gp |
| Teak plank | 500 gp | 350 gp |
| Mahogany plank | 1,500 gp | 1,050 gp |
That saving is real but small in absolute terms, 30, 75, 150 and 450 coins per plank respectively. The question is whether the runes cost less than that.
The rune cost is the whole story
At prices checked on 25 August 2026, one cast of Plank Make cost:
- 2 astral runes at 112 gp = 224 gp
- 1 nature rune at 142 gp = 142 gp
- 15 earth runes at 6 gp = 90 gp
- Total: 456 gp per cast
Compare that against the fee saving:
| Plank | Fee saving | Rune cost | Net |
|---|---|---|---|
| Plank | 30 gp | 456 gp | −426 gp |
| Oak plank | 75 gp | 456 gp | −381 gp |
| Teak plank | 150 gp | 456 gp | −306 gp |
| Mahogany plank | 450 gp | 456 gp | −6 gp |
On mahogany the two are effectively level. The rune cost eats the saving almost exactly. On every cheaper tier the spell loses money against the sawmill.
This is why the wiki notes that players generally cast Plank Make to train Magic rather than to save gold on planks.
All three routes compared
| Plank | Buy finished | Sawmill | Plank Make | Cheapest |
|---|---|---|---|---|
| Plank | 148 gp | 124 gp | 550 gp | Sawmill |
| Oak plank | 414 gp | 292 gp | 673 gp | Sawmill |
| Teak plank | 769 gp | 624 gp | 930 gp | Sawmill |
| Mahogany plank | 1,826 gp | 1,661 gp | 1,667 gp | Sawmill |
Sawmill totals are the log price plus the operator’s fee. Plank Make totals are the log price plus the reduced fee plus the 456 gp rune cost.
Prices checked 25 August 2026. Rune prices in particular move, and astral runes are the largest single component. A fall in astral prices narrows the gap fastest.
Lowest gold is not the same as best use of time
The table above ranks by gold spent. It says nothing about time, and the ordering reverses when you account for it.
Buying finished planks costs the most gold and takes one Grand Exchange offer. For a 9,660-plank mahogany table run, that is a single purchase.
The sawmill means buying logs, travelling to a sawmill, converting in inventory-sized batches and banking. Cheapest per plank, most trips. The cook, butler and demon butler can be sent to the sawmill on your behalf, which removes part of that burden, see the servant comparison.
Plank Make means gathering logs, gathering runes, and casting once per plank at three ticks each. Converting 9,660 mahogany planks is roughly 9,660 casts. That is hours of clicking to save nothing against the sawmill.
A rough rule: if the sawmill saves less than about 5 per cent over buying finished, the trips are rarely worth it. On 25 August 2026 the sawmill saved 9 to 30 per cent depending on tier, which comfortably clears that bar for anyone with the patience.
When Plank Make does make sense
The spell has a genuine place, just not as a money saver.
As Magic training. 90 Magic experience per cast, castable every three ticks. The wiki reports up to roughly 166,000 Magic experience per hour at optimal rates and around 90,000 on autocast, which compares favourably with High Level Alchemy. If you were going to train Magic anyway, the planks are a by-product rather than the point.
When you already have the runes. Astral runes accumulate on accounts doing Lunar activities. Planks converted with runes you were not going to sell are effectively cheaper than the table above suggests.
When rune prices fall. The mahogany line is within single-digit gold of breaking even. A modest fall in astral or nature prices flips it.
Which route for which situation
Buying a large mahogany order? Compare finished planks against logs plus 1,500 on the day. The gap was 165 gp per plank on 25 August 2026, which is 1.6m over a 9,660-plank run, worth the trips for most players.
Training Magic and Construction together? Plank Make, and treat the plank cost as close to the sawmill price.
Ironman? You are cutting the logs regardless, so the only question is sawmill or Plank Make. If you have 86 Magic and Dream Mentor done, the spell saves you a trip per inventory.
Short on time rather than gold? Buy finished planks and skip the whole question.
Working out your own total
Whichever route you pick, the plank count comes from your level, your target and your method, not from your plank supplier.
Open the Construction calculator, enter your current experience and target, and pick your method. Its Sawmill toggle prices logs plus the conversion fee against finished planks using values you enter, so you can see both totals for your own goal rather than a worked example.
For today’s rune and plank prices, the GE price tracker pulls live figures from the Old School RuneScape Wiki. For how the three plank tiers compare before you pick one, see the Oak vs Teak vs Mahogany comparison.
Sources for this plank supply guide
Plank Make requirements, rune cost, cast speed, Magic experience and the 70 per cent conversion rate come from the OSRS Wiki Plank Make page and are fixed game mechanics. Sawmill fees are fixed values. All gold figures use Grand Exchange insta-buy prices checked on 25 August 2026 and will change, particularly the rune costs, which decide the entire comparison.