How is the expected number of attempts calculated?

Each upgrade attempt is modelled as an independent trial with success probability p. The expected number of attempts to succeed once is 1 / p, the mean of a geometric distribution. Costs follow the same rule: expected cost = cost per attempt / p.

Why does the success rate drop at higher levels?

Higher enchant levels are intentionally harder. The model multiplies the base rate by 0.92 for each level above the first, with a 5% floor so an upgrade is never strictly impossible.

Are these the exact in-game RuneScape 3 rates?

No. RuneScape's exact rates change between updates and differ per item. This is a community estimator that gives a realistic planning baseline, not an official value.

Why is the expected cost higher than attempts times base cost?

Because every failed attempt still consumes materials. When success is uncertain you pay for the failures too, so expected cost scales as base cost divided by success probability.

Does this tool send my data anywhere?

No. All probability and cost maths runs entirely in your browser. Nothing is uploaded or stored on a server.

RuneScape 3 Enchant & Gear Score Calculator

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Plan RuneScape 3 gear upgrades before you spend the gp

Upgrading high-tier gear in RuneScape 3 is a gamble: each attempt can fail and burn your materials. This calculator turns that gamble into numbers. Pick a tier, set your current and target enchant levels, and it estimates how many attempts and how much gp you should expect to spend.

How it works

Each upgrade attempt is an independent trial with a success probability p. The number of tries needed to succeed once follows a geometric distribution, whose mean is 1 / p. So if a step has a 50% success rate, you should expect about 2 attempts on average.

The per-attempt success rate falls as the level rises. Starting from the tier’s base rate, each level above the first multiplies the rate by 0.92, with a 5% floor. The gp cost per attempt grows 35% per level. Because failures still cost materials, the expected cost for a step is cost per attempt / p, and the tool sums attempts and cost across every step from your start level to your target.

Example and tips

Going from +0 to +5 Dragon: the early steps succeed most of the time and are cheap, but the final steps drop below 60% and the cost per attempt compounds — so most of your gp goes into the last one or two levels. If a step shows a very low success rate, consider stockpiling materials before you start so a long unlucky streak does not strand you mid-upgrade. Treat the totals as planning estimates and pad your budget by 20–30% for variance.