How to read the result
The base bet sets the scale. The paid-action multiplier sets the charge. Total returned means the entire settled return, including any amount that merely replaces part of the charge. Net is returned minus charged. Green means a positive net in your example; red means a loss; zero is neutral.
The default example spends 75 units on Ultra and returns 60, leaving −15. Switching to ordinary Bonus with the same base and return spends 30, leaving +30. This compares arithmetic at an assumed return, not the probabilities of the two modes.
You can read the units as rand for a budgeting example, but the tool does not verify a rand stake menu or payment route. A base of R2 makes the original Bonus purchase R60 and Ultra R150. The rules in your actual session remain authoritative.
What this calculator cannot decide
The tool does not know the next result, estimate a bonus trigger or select a profitable mode. It uses the original game’s documented purchase multiples. Do not apply it unchanged to Coin Volcano 2 or another similarly named title.
For a naturally triggered feature, include the earlier ordinary spins if your question is session profit. The single-action calculator does not automatically add them. If twenty failed R1 spins precede a triggering R1 spin returning R25, the session net is +R4 after R21 spent.
An unfinished feature is not a final return. Wait for settlement before entering its result. For more detail on valid recording and return denominators, read the strategy and RTP guide.