First-Set Winner Calculator

The market question behind this calculator

Convert a user-entered rating difference into a fair win probability and price. Changing the selection or grading window creates a new First-Set Winner Calculator case rather than an update to this one; do not use extra decimal places as a substitute for uncertainty.

Surface, serve and return form, fitness, opponent, and likely match format should come from the same event. One source of disagreement outside the arithmetic is that account for tie, draw, and no-action rules before comparing a fair probability with the offered price.

Reproduce the method before using current data

For the First-Set Winner Calculator, the example is deliberately separate from the loaded scenario and should be read as a method check, not betting advice.

Selected side rating is set to 3.76 rating points for this worked case.

Opponent rating is set to 2.24 rating points for this worked case.

Venue or surface adjustment is set to 0 rating points for this worked case.

Rating points per logistic step is set to 7.35 points for this worked case.

Applying the First-Set Winner rule: win probability = logistic((selected rating − opponent rating + adjustment) ÷ scale).

• Fair odds: -123
• Rating difference: 1.52

For this estimated win probability example, review the formula line and field units if the supporting values disagree with the displayed worked result.

The Tennis Match Win Probability is relevant only if that separate result also affects the decision; it is not an extra input to estimated win probability.

Check the scope of each input

The First-Set Winner Calculator uses Selected side rating as its first input; power rating for the selected side; note when it was current.

Source Opponent rating for the exact event represented here; power rating on the same scale; do not borrow it from a different period.

Venue or surface adjustment belongs to the same snapshot as the other First-Set Winner Calculator values; positive values favor the selected side; save the source type.

Before calculating estimated win probability, check Rating points per logistic step: controls how strongly rating differences affect probability; its timestamp should match the market comparison.

Do not revise an unrelated field merely because fitness news or a surface change can make historical averages poor inputs.

If the analysis moves from estimated win probability to first-serve percentage, continue with the First-Serve Percentage rather than silently carrying assumptions across.

How the calculation reaches estimated win probability

Calculation: win probability = logistic((selected rating − opponent rating + adjustment) ÷ scale).

For the First-Set Winner Calculator, the rating gap is shifted by the venue or surface term before a logistic conversion produces the win probability.

Use Venue or surface adjustment in the First-Set Winner Calculator only as described here: positive values favor the selected side.

Do not combine statistics from different periods merely because they use the same unit; their market scope also has to match; use a separate case when the market definition changes.

Keep tennis game handicap separate. The Tennis Game Handicap provides the matching form and result.

Cases that can invalidate the comparison

The rating scale must be calibrated to the sport and competition.

Review retirement, walkover, best-of format, and completed-set requirements before comparing the output with a price.

A final pre-comparison check for this page is that account for tie, draw, and no-action rules before comparing a fair probability with the offered price.

Keep a usable record

Store estimated win probability with enough context to distinguish market movement from a changed assumption; preserve the source and timestamp for “Opponent rating.”

A changed “Selected side rating” should produce a dated second result rather than silently replacing the first; retain the original result for comparison.

Questions specific to this calculation