Idle Game Upgrade Payback Calculator

Understanding the idle game upgrade payback calculator — concept and principle

In idle and incremental games, almost every decision is "which upgrade should I buy next?". The best general rule is to compare how quickly each upgrade pays for itself. This calculator takes an upgrade's cost, the extra production per second it adds and your current production per second, and returns the payback time, the time needed to afford it at your current rate, and the cost per unit of gain.

Saving up and paying back are separate clocks; compare upgrades by the payback one.

How it is calculated

Payback time = upgrade cost ÷ extra production per second.
Time to afford now = upgrade cost ÷ current production per second.
Production after upgrade = current production + extra production per second.

The payback time in seconds is also the cost per unit of extra production, so sorting by payback is the same as sorting by cost per gain.

Times are shown in seconds below one minute, in minutes below one hour, and in hours beyond that.

The principle

An upgrade is an investment: you give up a lump of currency now in exchange for a stream of extra currency later. Payback time is how long that stream takes to return the original cost; after that, the upgrade is pure profit. If you always buy the option with the shortest payback, your production rises as fast as possible in the short run, because every unit of currency goes where it earns back the most per second. The time to afford tells you how long you must save first, which matters when comparing a cheap upgrade now with an expensive one later.

Worked example

Inputs: cost 5,000, extra production 12 per second, current production 40 per second.
Payback time = 5,000 ÷ 12 ≈ 416.67 s, shown as 6.94 min.
Time to afford now = 5,000 ÷ 40 = 125 s, shown as 2.08 min.
Production after upgrade = 40 + 12 = 52 per second.

Each point is the calculator re-run with only “Extra production per second” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Extra production per second	Payback time
3	27.8 min
6	13.9 min
9	9.26 min
12	6.94 min
15	5.56 min
18	4.63 min
24	3.47 min

How to read the result

Run the calculation for each upgrade on offer and sort by payback time. An upgrade costing 2,000 for +4 per second (500 s payback, 8.33 min) is worse than this one (416.67 s), even though it is cheaper. When payback time is longer than you plan to keep the current run, for example right before a prestige reset, the upgrade never pays off and you should skip it.

Common mistakes

Comparing upgrades by price rather than by cost per unit of production.
Ignoring multipliers: a +10% global boost must be converted to extra production per second (10% of your current total) before comparing.
Forgetting that cost often rises after every purchase, so the next copy has a longer payback.

Keep in mind: Payback is a greedy short-term rule. It ignores compounding effects, unlocks and prestige timing, which can make a slower-payback upgrade the better long-term choice. Use it as a default, not a law.

Frequently asked questions

Is shortest payback always optimal?

Not always, but it is a strong default; refinements also account for the waiting time before you can afford each option.

How do I compare a percentage upgrade?

Multiply the percentage by the production it affects to get extra production per second, then use that as the gain.

Sources: Richard A. Brealey, Stewart C. Myers and Franklin Allen, Principles of Corporate Finance (payback period)

Checked 8 Nov 2026. Official league / federation formulas where they exist; widely used community formulas otherwise. For fun and analysis — not betting advice.

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