Burst vs commit in this calculator is on-demand plus overage minus commit after discount. With 12 on-demand USD/M, 8 commit USD/M, 40 token millions, 15 overage %, 20 discount % the result is $296.00 | $256.00.
burst = tokens × on-demand × (1 + overage%/100). commit = tokens × rate × (1 − discount%/100). The first amount is the gap. The formula uses tokens and overage.
$296.00 | $256.00 is not an AWS price list. Another set of numbers gives $63.36 | $95.04, and a further set gives $1,096.80 | $660.00. Empty scenario fields do not change the result.
Tool-call unit economics answers a different question. MCP cost does too. Here 12 on-demand USD/M, 8 commit USD/M, 40 token millions, 15 overage %, 20 discount % leave $296.00 | $256.00.
Type 12 on-demand USD/M, 8 commit USD/M, 40 token millions, 15 overage %, 20 discount % and click Calculate. Two more ready sets sit under the form: $63.36 | $95.04 and $1,096.80 | $660.00.
Other numbers on the same labels move the result. The first example gives $296.00 | $256.00.