Start with the fixed commitments
Record your actual accommodation quotes, intercity tickets and any prepaid activities in THB. Put the date beside each quote. Keep international transport and insurance separate so the daily comparison does not disguise them.
Make variable costs explicit
Choose your own allowance for meals, local transfers and incidental purchases. The planner’s calculator is a worksheet using your inputs, not a survey of Thai prices. Add a contingency that reflects your own tolerance for changes.
Compare two versions
Try one fewer base, a different room category or more unscheduled days. Compare total cost and useful time together. The cheapest version is not automatically the best one; the useful version makes its tradeoffs visible.