How do I calculate how many tries a drop takes?

With chance p per try, the number of tries after which a share q of players have the item is ln(1−q) ÷ ln(1−p), rounded up. A 1% drop takes 69 tries for half of players and 230 tries for 90%. A pity counter that guarantees the item on try N lowers the expected tries to (1−(1−p)^N) ÷ p.

Can I use the curve in Godot, Unity or Unreal?

Yes. Export CSV or JSON, or copy a ready GDScript or C# array. The paid workbook adds loaders for Godot 4, Unity and Unreal DataTables.

The web calculator is free and runs in your browser. The Grindscale workbook, with the full economy model, is a one-time $7 purchase.

Free XP curve calculator: see hours to every level

For game designers and indie devs. Pick a curve, see how long each level takes to play and whether max level lands on your target, then export it to Godot, Unity or Unreal. Free, in your browser. Need the whole economy? The Grindscale workbook is $7.

Settings

Start from

Max level

Curve

XP for level 1 → 2

Round to

Extra XP per level

Power exponent

Growth per level

Share of exponential

Play time

XP per hour at level 1

XP per hour growth

Target hours to max

Sessions a day

Minutes a session

Total XP to max–

Hours to max–

vs your target–

Days (typical player)–

Gold, shop prices, loot and upgrades too? Grindscale workbook: the whole economy in one spreadsheet, $7 →

Level	XP to next	Total XP	XP/hour	Hours	Total hours

Drop rate & pity calculator

How many kills, chests or pulls until players get the item? Enter a chance per try.

Chance per try (%)

…or 1 in

Pity: guaranteed on try (optional)

Tries per hour

Half of players by try–

9 in 10 players by try–

99 in 100 by try–

Expected tries–

Hours for 9 in 10–

Chance within tries–

Grindscale workbook: the whole game economy in one spreadsheet

Everything above, plus the rest of your economy. Works in Excel, Google Sheets, LibreOffice and Numbers; no macros, no add-ons.

Economy: up to 12 gold faucets and sinks with growth and unlock levels; wallet by level; inflation warnings
Shop: prices from "hours of saving" at the unlock level, or check your own prices
Drops: whole loot tables from weights, 1-in-N, tries for 50/90/99%, pity
Upgrades: +1 … +15 with failure chances → expected attempts and total cost
60-day simulator: level and gold of a typical player each day
4 presets: mobile casual, classic RPG, long-haul RPG, roguelite meta
Engine loaders: Godot 4 script, Unity ScriptableObject, Unreal DataTable struct, plus ready CSV/JSON tables

Workbook$7one-time · unlimited games · commercial use · your studio's teamBuy on Polar

Indie Game Dev Bundle$25 ~~$30.99~~Grindscale + Tintmoor 60 LUTs + Fernscatter Nature PackGet the bundle

Classroom$29for teachers: share with up to 40 students of one courseClassroom licence

Secure checkout by Polar. Questions: cybermax.tools@gmail.com

Grindscale Settings sheet: preset, inputs and the summary with hours to max level and a verdict — The Settings sheet with its summary (shown in LibreOffice; also Excel and Google Sheets).

Questions

What is a good XP curve formula?

Most RPGs use a power curve (XP = base × level^1.5–2.2) or an exponential one (XP = base × growth^level−1, growth 1.05–1.20). A blend keeps early levels quick and late ones long without exploding. What matters is time, so compare hours per level with how long you want players to take.

Why does XP per hour matter?

Players earn more XP at higher levels (tougher enemies, bigger quests). If XP needs grow at the same rate as XP per hour, every level takes the same time. Make needs grow a little faster and levels slow down gently.

How is "tries for 90%" worked out?

With chance p per try, the share of players who have the item after n tries is 1 − (1 − p)ⁿ. Solving for 90% gives n = ln(0.1) ÷ ln(1 − p), rounded up. A pity counter guarantees the item on try N, so no player waits longer than N tries.

Why not just use a free calculator (like this one) or a blank spreadsheet?

Use this page free for XP curves and drop chances. The workbook is for when the numbers have to work together: gold earned per hour against sinks, shop prices against savings, upgrade costs against income, and a player simulated day by day. Building and checking that yourself takes days; here it is tested and ready, with loaders for your engine.

Why not a web-based balancing tool?

A spreadsheet is yours: it works offline, you can add your own sheets and formulas, share it with your team in Google Sheets, and it never goes away with a subscription.

What do I get after paying?

An instant download (zip, about 75 KB): the .xlsx workbook, ready CSV and JSON tables for 4 presets, the Godot 4 / Unity / Unreal loaders and a quick-start guide. One-time payment, checkout by Polar.

Is anything uploaded?

No. The calculator runs entirely in your browser. The link button stores your settings in the page address only.

Ship a game economy that feels right

Every sheet updates the moment you change a yellow cell: XP, gold, shop, loot, upgrades and a 60-day player.

Get Grindscale · $7