How to Use the Upgrade Expected Cost Calculator
When upgrading gear in a game, looking at the success rate alone makes it hard to know how much currency you'll actually need. This calculator takes your success, downgrade, and destroy probabilities plus the cost per attempt, and statistically computes the expected number of attempts and average total cost to go from your current level to your target level.
Under the hood, it builds expected-value equations for each level: a success moves you up one level, a plain failure keeps you where you are, a downgrade drops you one level, and a destroy sends you all the way back to level 0. Those equations are solved through iterative approximation. With no downgrade or destroy, the result simplifies to 1 divided by the success probability, multiplied by the number of levels needed.
The higher the downgrade and destroy odds, the more the expected cost grows — often exponentially. A destroy probability in particular forces a full restart on failure, which can dramatically inflate the average cost. Knowing this ahead of time and budgeting with room to spare is the safest way to avoid nasty surprises from a bad upgrade streak.
Frequently Asked Questions
Downgrade probability means a failed attempt drops your item one stage lower, while destroy probability means the item is lost completely and you must restart from stage 0. Higher values for either sharply increase expected attempts and cost.
The calculator sets up expected-value equations for each stage using your success, stay, downgrade, and destroy probabilities, then solves them iteratively. Without downgrade or destroy, it simplifies to 1 divided by the success probability.
Yes, the average is just an expected value — actual results vary widely due to randomness. A run of bad luck can cost two to three times the average, so budget with a safety margin.