OSRS Barrows Calculator: Drop Tables & EV Update

September 21, 2025•v2025.09 Release

Today's release refreshes every Barrows data point in LootCalc and revisits how EV/GPH and any-unique probability are visualised. You'll see clearer KPIs, safer defaults (40 runs per hour baseline), and share links that only encode public inputs. Everything here is based on wiki-confirmed drop tables and a fresh Grand Exchange snapshot captured on 21 September 2025.

✨ What's New

v2025.09 Changes at a Glance

✓Drop table & GE price snapshot refresh (snapshot: 2025-09-21)

✓Compact KPI formatting (e.g., "7.1M"), so numbers never overflow on mobile

✓Stable defaults (90 s runtime → ~40 runs/hr) across SSR and CSR render paths

✓Share URLs encode only numeric inputs; overrides remain local to the browser

📊 Example Before/After

With a 90 s runtime and realistic consumable costs, GPH now renders as a compact 2.0M rather than stretching the KPI card. The same preset also exposes the updated union-probability chart showing the odds of any unique inside 20, 40, and 80 chests.

📝 Notes & Caveats

• Prices are snapshots—override any item inside the calculator to match your world or clan buy prices
• Repair costs default to 90k/hr. If you camp underground without Dharok, drop this to match your repairs

Version & Sources

Data: OSRS Wiki & GE snapshots (v2025-09). Calculator UI build v2025.09. Share links expose only the runs, runtime, and costs inputs.

Accuracy & Methodology

🎯 Mutual Exclusion for Barrows Uniques

A Barrows chest rolls at most one unique per kill. LootCalc models the chest as a mutually exclusive table with six unique slots, rune/bolt stacks, and coins. We calculate P(any unique) using union probability: 1 - ∏ᵢ (1 - pᵢ) for the six slots. This is why the "any unique" percentage changes when patch notes tweak a single item's drop rate.

📐 Worked Example

Suppose the combined chance of any unique per chest is p = 1/16. After n chests, the chance you have seen at least one unique is:

1 - (1 - p)^n

With n = 40 the probability jumps to ≈91.5%, matching the calculator's "cumulative odds" readout.

⚠️ Edge Cases

• Pity mechanics do not exist for Barrows—if Jagex introduces them, the calculator will expose a toggle
• For duo or trio runs, EV per player changes because rune/bolt splits differ; set team size before sharing links

📖 How to Read the Outputs

💰 EV (per run)

EV answers "is each run worth it?"—the long term average value of a single Barrows chest with your inputs. Multiply EV by runs to estimate long-term profit; keep in mind variance can be brutal.

⏱️ GPH

GPH divides EV minus costs by your minutes per run. We default to 90 seconds (≈40 runs/hr). If you run longer routes—e.g., banking rune stacks—adjust runtime and costs to keep predictions realistic.

🧮 Quick Math

Example: EV/run = 52,300 gp, runtime = 90 s, costs = 18,400 gp. Runs per hour ≈ 40, so GPH ≈

(52,300 - 18,400) × 40 ≈ 1.35M

The calculator renders this automatically, and we now surface the compact number without clipping.

Common Pitfalls

• Runtime accidentally set to 0 or 1 s → unrealistic 3600 runs/hr. Defaults now guard this
• Forgetting to include stamina potions, rune pouch charges, or repair costs skews GPH upwards
• Sharing a link after overriding item prices? Those overrides stay local—include a note for teammates
• Variance is high. A three-unique streak does not mean EV is wrong; check the cumulative probability table
• Clan split rules matter. If you split uniques, divide the EV by team size

Migration & Links

🔗 URL Sharing

Links include core inputs such as:

?runs=64&runtime=90&cost=20000

Overrides remain client-side so you can safely share the same link publicly without leaking your experimental items.

💬 Feedback

Spot a mismatch with new patch notes or want a new preset? Open an issue on GitHub or ping us on Discord. We roll Barrows updates alongside major GE swings and Jagex balance patches.

Changelog

2025-09-21: Data refresh, KPI compaction, default/runtime fix, share URL safety.