Stone Skipping: Every World 2 Stone Cost & Skill Boost

This calculator works out the total cost and the skill boost you get from every stone in World 2 of a typical idle/incremental game. You enter the number of stones you already own and the stone level, and it returns the exact gold cost for the next purchase and the cumulative skill boost percentage you have accumulated.

Formula

The two formulas used here are the standard exponential cost curve and a linear boost formula common in idle games.

• Next stone cost = 100 × 1.15ⁿ, where n is the number of stones you already own. The base cost is 100 gold, and each stone you buy increases the price of the next one by 15%.
• Total skill boost = 5 × l × n, where l is your current stone level (usually 1 to 5) and n is the number of stones owned. Each stone gives a 5% boost per level.

Worked Example

Using the default values: you own 10 stones (n = 10) and your stone level is 1 (l = 1).

1. Next stone cost = 100 × 1.15¹⁰ = 100 × 4.0456 = 404.56 gold, which rounds to 405 gold.
2. Total skill boost = 5 × 1 × 10 = 50%.

The calculator shows the same numbers: 405 gold and 50.0% boost.

How Stone Costs Scale in World 2

World 2 introduces a separate stone economy from World 1. In most games of this genre, stones are a premium currency you earn from bosses, daily quests, or idle rewards. The cost curve is designed to slow your progress: early stones are cheap (100, 115, 132 gold), but by stone 20 the price jumps to over 1,600 gold, and by stone 50 it exceeds 100,000 gold.

This exponential growth means that there is no “best” number of stones to own — it depends on your gold income. A general rule is to buy stones when the cost is less than 10% of your current gold reserve, because the boost is permanent and never resets.

How the Skill Boost Works

The skill boost is a multiplier applied to all experience, damage, or resource gain — depending on the game. In most implementations, each stone adds a flat percentage that is multiplied by the stone level. For example:

• Level 1 stone: each stone gives 5% boost.
• Level 2 stone: each stone gives 10% boost.
• Level 3 stone: each stone gives 15% boost.

So if you have 20 stones at level 3, your total boost is 5 × 3 × 20 = 300%. This is a linear increase, meaning that doubling your stones doubles your boost. The trade-off is that the cost grows exponentially, so you eventually hit a wall where the next stone costs more than the boost is worth.

How to Choose When to Buy

There is no single optimal strategy, but players generally follow one of these patterns:

• Early game: Buy stones as soon as you can afford them, because the boost accelerates your gold income, which helps you buy more stones faster.
• Mid game: Save up for a batch of 5-10 stones at once, because the cost curve is steep and buying one at a time feels inefficient.
• Late game: Only buy stones when the cost is below 1% of your total gold, because other upgrades (like production buildings) may give a better return on investment.

A common mistake is to buy stones too early, leaving you with no gold for essential upgrades. Another mistake is to ignore stone level upgrades — raising the level from 1 to 2 doubles the boost from every stone you already own, which is often cheaper than buying many new stones.

Common Mistakes and Misconceptions

One frequent error is confusing the stone cost formula with a linear one. Players assume that if stone 10 costs 400 gold, stone 20 will cost 800 gold. In reality, it costs over 1,600 gold — four times more. Always use the exponential formula, not a linear guess.

Another misconception is that the skill boost applies to gold income only. In many games, it applies to all skills — mining, combat, crafting, and magic. Read the in-game description to see exactly what it boosts. If it boosts everything, it is almost always worth buying.

A third mistake is ignoring the stone level. Some players spend all their gold on new stones and never upgrade the level, missing out on the multiplier. A good rule is to keep your stone level at least half of your stone count.

Cost Comparison: Stones vs. Other Upgrades

In World 2, you usually have several upgrade paths: stones, buildings, and equipment. A quick comparison:

• Stones: Permanent boost, but exponential cost. Best for long-term progress.
• Buildings: Linear cost, but may have a cap (e.g., max level 50). Better for short-term gold generation.
• Equipment: One-time cost, but becomes obsolete as you progress. Not a permanent investment.

If you have limited gold, a good strategy is to buy buildings first to increase your gold per second, then use that increased income to buy stones. This gives you the best of both worlds.

Safety and Fair Play

This calculator is for informational purposes only — it does not modify your game or give you an unfair advantage. Always play by the game’s rules. Using third-party tools to automate stone buying or to cheat the cost formula can result in a ban. The formulas here are based on publicly available game mechanics and are meant to help you plan your spending, not to exploit bugs.

Limits of the Formula

The formulas assume a standard exponential cost and a linear boost. Some games use different curves — for example, a quadratic cost (cost = 100 × n²) or a diminishing boost (boost = 5% × n / (1 + n)). If your game does not match these numbers, adjust the formula accordingly. Also, the cost formula does not include any discounts from achievements or events, so the actual cost may be lower than the calculator shows.

Frequently Asked Questions

What is the best stone level in World 2?

There is no single best level — it depends on your gold income. However, a common strategy is to keep your stone level at 3 or 4, because the cost to upgrade from level 4 to 5 is often very high, and the extra 5% per stone may not be worth it until you have many stones.

Should I buy stones or save for the next world?

If you are close to unlocking World 3, it is usually better to save your gold, because the next world offers new upgrades that may give a bigger boost. But if you are stuck and need more power, buying a few stones can help you progress faster.

Does the skill boost apply to idle gains?

In most games, yes — the boost applies to all gains, including idle gains. Check the in-game description to be sure, but generally stones are a safe investment for both active and idle play.

How do I get more stones in World 2?

Stones are typically earned from defeating bosses, completing daily quests, or as random drops from monsters. Some games also let you buy stones with real money, but that is optional.

Is the cost formula the same for all stones?

No — the formula I used (100 × 1.15ⁿ) is a common one, but your game may use a different base or growth rate. Check the game’s wiki or data files to find the exact formula, then adjust the calculator’s base value (100) and growth rate (1.15) accordingly.

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in n | Stones owned | - | 10 | 0
in l | Stone level | - | 1 | 0
out cost | Next stone cost | gold | 100 * pow(1.15, n) | 0
out boost | Total skill boost | % | 5 * l * n | 1