How is the expected number of attempts calculated?

For an independent attempt with success probability p, the number of tries until the first success follows a geometric distribution whose mean is 1/p. The tool sums 1/p across every level you still need to gain.

Why does a 10 percent rate need about 10 attempts per level?

The expected attempts for one success is 1 divided by the probability. At 10 percent (0.10) that is 1/0.10 = 10 attempts on average, though any single run can take many more or fewer due to variance.

Does this guarantee how many attempts I will actually need?

No. It reports the statistical average, not a fixed count. Real runs vary widely because each attempt is independent; you may get lucky in 3 tries or unlucky and need 30 for the same expected-10 level.

Can I model success rates that change per level?

This tool assumes one fixed rate across all levels for simplicity. If your higher levels have lower odds, run it level-by-level with the matching rate and add the results together for a more accurate total.

What happens at a 0 percent or 100 percent rate?

At 100 percent every attempt succeeds, so you need exactly one attempt per level. At 0 percent success is impossible and the expected attempts are infinite, so the tool flags it rather than dividing by zero.

EVE Online Enchant & Gear Score Calculator

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Enchanting and gear upgrades in EVE Online are gambles: each attempt either succeeds or fails with a fixed probability. This calculator turns that probability into the numbers you actually care about — how many attempts you should expect, and how much currency that will cost on average — before you commit your materials.

How it works

When each attempt is independent and succeeds with probability p, the number of attempts needed for one success follows a geometric distribution. Its mean — the expected number of tries — is:

expected attempts per success = 1 / p

To go from your current level to a target level you need (target − current) successes, so the total expected attempts and cost are:

levels needed   = target − current
total attempts  = levels needed × (1 / p)
total cost      = total attempts × cost per attempt

This is the correct way to budget for any fixed-rate upgrade system: the average cost scales inversely with the success rate, so halving your odds roughly doubles your expected spend.

Example and tips

At a 20 percent success rate, one success takes 1 / 0.20 = 5 attempts on average. Climbing four levels needs about 4 × 5 = 20 attempts. If each attempt burns 10 units of material, budget for roughly 200 units — but keep a reserve, because variance means an unlucky streak can easily double that. Where the game offers protection items or pity systems, factor them in separately; this model assumes pure independent trials.