Mine a Mountain Bomb ROI and Break-Even Calculator

The Mine a Mountain Bomb ROI Lab is the third of the wikis calculators. Where the Time-to-Target Calculator measures grind progress and the Upgrade Path Optimizer picks the next upgrade, the Lab isolates the math behind bombs: how much gross cash a single bomb use should net you, what your break-even collection share is, how that number compares across all 8 catalog bombs, and whether a measured sample confirms or contradicts the projection.

What the lab does not do

• It does not endorse a “best bomb”. Published tier lists rank bombs by qualitative pool notes; the lab ranks them under your measured collection share and average value.
• It does not model the full crystal value function. The crystal weight-to-final-value formula is not exposed, so the lab relies on player-observed sales samples, not reconstructed value.
• It does not auto-apply x2 Crystals to cash. A 2× crystal count does not automatically double your cash because bag capacity and pickup time cut collection share. The lab displays x2 Crystals as a separate input.

The catalog

Eight bombs are documented in the live build (verified 2026-07-30 across two community guides).

The wiki stamps every cost with the 2026-07-30 verification date. The lab lets you override any cost after a game update.

Inputs

A separate “raw sample” mode accepts n measured bomb gross sales; the lab computes mean gross per use, loss probability, and uses-to-cover-progression. The sample mode is the honest test when the published formula is uncertain.

The math, layer by layer

Without mutation modeling:

gross_per_use [$]   = N × η × V × Ms
net_per_use [$]     = gross_per_use − Cb
ROI [%]             = 100 × net_per_use / Cb
profit_per_hour [$] = (net_per_use / Tb) × 3600

With mutation modeling:

expected_mutation_factor = (1 − pm) × 1 + pm × E[Mm]
gross_per_use            = N × η × V × expected_mutation_factor × Ms

For a uniform mutation range [a, b], E[Mm] = (a + b) / 2. The community wiki reports a=1.5, b=2.5 for Thunder and Poison, and a=1.2, b=1.8 for Wet. The lab lets you edit both bound values and the mutation chance after every update.

Detonation Rune bonus: When active, N becomes N × 1.40 (a documented 40% crystal bonus). The lab applies this once; it does not multiply cash directly because pickup time and collection share also change.

Break-even thresholds:

η* (collection share)    = Cb / (N × V × mutation_factor × Ms)
V* (value per crystal)   = Cb / (N × η × mutation_factor × Ms)

If η* exceeds 100%, the bomb cannot break even under current assumptions. The lab displays “Unreachable” with a hint to widen N, push pm, or measure a higher V.

Sample mode

When your crystal V is uncertain, raw sample mode is more honest:

mean_gross_per_use = ΣGi / n
loss_probability   = count(Gi < Cb) / n

If the lab sees loss_probability > 30%, it warns that your sample’s loss rate exceeds the threshold — and asks you to verify the route or the mutation rate. The sample’s mean gross is used to project “uses to recover a higher-tier bomb progression” if you supply a target upgrade cost.

Edge cases the lab handles

• Bag fills mid-blast. The lab uses your observed collection share. It does not multiply cash by 1.40 if x2 Crystals is on; it asks you to enter the actual spawn count and collection share.
• Zero-cost bomb. ROI division is skipped. Gross and net are still surfaced.
• Mutation stacking. The lab allows one base mutation + Radioactive per crystal; it does not multiply multiple mutation multipliers together.
• Already-mutated crystals. The lab does not apply a bomb’s mutation chance to inventory that pre-exists the bomb use.
• Currency mismatch. Robux values in a $ field are flagged and not converted.
• Negative net. Displayed as a loss with the explicit −$ figure; never hidden behind a tier score.
• Time Bomb and Agony claims. The qualitative descriptions (“reported second-richest pool”) are surfaced as notes only, not as numbers. The lab asks for measured values when you mark a bomb’s pool as uncertain.

Worked example

You have measured Thunder with:

• N = 6 crystals per blast (5 typical, 7 on a good mountain)
• η = 0.6 (you pick up about 60% under public-server pressure)
• V = 250,000 $ per crystal on the average mountain
• Ms = 1 (no sale multiplier)
• pm = 0.3, Mm ∈ [1.5, 2.5]
• No Detonation Rune; Tb = 60s per cycle; Cb = 15,000,000

Expected mutation factor = 0.7 × 1 + 0.3 × 2.0 = 1.30. Gross = 6 × 0.6 × 250,000 × 1.30 = 1,170,000. Net = 1,170,000 − 15,000,000 = −13,830,000. ROI = -92.2%. The lab surfaces this as a clear loss before you spend.

That is the value of the lab: a route that feels rich because Thunder is “good” loses money under current rates. The lab catches it before you spend.

When the lab is wrong

The lab is wrong when the inputs are wrong. Three honest ways it can misfire:

1. Crystal value V is too optimistic. If your sample mean is 150,000 and you typed 250,000, the lab over-projects. Run a 10-use sample first.
2. Collection share is too high. In a busy public server, η = 0.4 is more realistic than η = 0.8.
3. The mutation rate has shifted. After a Fandom-reported patch, mutation chances may change. The lab lets you override pm and Mm defaults.

If your measured sample says gross ~1,100,000 for 6 crystals and the lab projects ~1,170,000, the lab is calibrated. If the lab projects 1,500,000 and you measured 800,000, recalibrate your V and pm.

FAQ

Should I prioritize Thunder or Poison? It depends on whether your measured runs surface Thunder mutations more often than Poison mutations. Use the lab’s comparison row to pick.

How long should my measured sample be? A 10-bomb sample across the same mountain reduces noise. Stale samples after a mountain rotation count less.

Where do I find $V$? $V$ is the average pre-mutation crystal value. Sell crystals you would normally keep, divide by count, and enter. The lab is honest about what its inputs measure.

Sources

• All Things How — every bomb (community) — checked 2026-07-30
• GameGeekFusion — bomb tier analysis (community) — checked 2026-07-30
• Mine a Mountain Fandom — Mutations (community) — checked 2026-07-30
• Mine a Mountain Fandom — Crystals (community) — checked 2026-07-30
• Mine a Mountain Tools Design Spec — Bomb ROI Lab (this wiki) — current revision