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LootCalc

Your rate, your route, visible assumptions

Borderlands 3 Drop Scenario Calculator

Turn a rate you can support and a route time you measured into cumulative target probability, expected attempts, and expected time. No boss, item, anointment, or Mayhem multiplier is silently preloaded.

Build a drop scenario

Enter a rate from your current source or a documented dataset. Mayhem and source menus are labels only. The 10% starting rate and 60-second cycle are examples—not Gearbox values or hidden boss presets.

For organizing comparisons only; it never changes the rate.

Record your setting, then enter the rate separately.

A note for the shared URL; item names do not load probabilities.

Example default only. Replace it with a rate tied to the exact source and game state.

Use 100% for any copy. Enter a conditional part/roll chance only when you can support that assumption.

A whole-number horizon for cumulative probability.

Expected attempts and time scale by this count.

Include combat, loading, looting, travel, and reset time measured for your route.

Chance within plan

99.48%

Effective target chance

10.00%

Expected attempts for 1

10

Expected time

10.0m

Cumulative target probability99.48%

Expected target copies per hour: 6.000

No-target chance within plan: 0.52%

Attempts to 50%: 7

Attempts to 75%: 14

Attempts to 90%: 22

Mayhem context is not a numeric rate table

2K's official Mayhem 2.0 overview says Mayhem increases challenge in exchange for better loot, and that dropped weapon stats improve as levels rise. It does not publish a universal per-level legendary multiplier, dedicated-drop table, variant pool, or universal numeric scaling formula. Those values are therefore not embedded here.

2K: Borderlands 3 Mayhem 2.0 overview

What the two probability inputs mean

The target drop chance is the probability that one complete attempt produces the item you are tracking. The desired variant chance is conditional on that drop. If the first chance is p and the conditional chance is v, the effective target probability is p × v. Leavev = 100% when any copy counts.

Probability and time formulas

For independent attempts, success within n cycles is 1 - (1-p)^n. Expected cycles for one target are 1/p; for k target copies the expectation is k/p. Expected time multiplies the latter by your full measured cycle time. None of these values guarantees an outcome.

Compare routes without smuggling in a rate

Save one URL per route using the same definition of “target.” A slower route wins only when its supported target probability rises enough to offset the extra combat, loading, travel, looting, and reset time. The related evidence-first farming guide gives a blank log schema.

FAQ

Does choosing a Mayhem level change the calculator's rate?

No. Mayhem is a label for your saved scenario. Enter the target chance separately from a source that matches the exact item, enemy, event, and game state.

What does desired variant chance mean?

It is an optional conditional chance after the target item drops, such as a particular part or roll. Use 100% when any copy counts, and enter a lower value only when you can support the assumption.

Why does cycle time include loading and looting?

Drops per hour depend on the complete repeatable loop, not only combat. Measure from the start of one attempt to the point where the next attempt can begin.

Are the expected attempts a guarantee?

No. They are the mean of the independent-rate scenario you entered. A 90% cumulative threshold still leaves a 10% no-target outcome.

Correction history

  • 2026-07-11: Removed hard-coded Mayhem scaling, boss/item rates, variant pools, route timings, fabricated sample logs, and unsupported validation or accuracy claims.
  • 2025-11-23: Initial calculator published.

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