Tipster ROI audit: a hypothetical 15.5% return that turns into a loss

What a tipster reports is not always what a follower earns. A selection can look profitable at the published price yet lose money when the same outcomes are settled at odds available after the tip arrives. To make that problem auditable, we built a transparent, deliberately hypothetical 120-selection benchmark and recalculated it across six prices, then added a simple subscription-cost example and a sample-uncertainty check.

Important scope: these 120 selections are a teaching scenario, not real picks, not a backtest of Tennis Tips UK or another service, and not proof that any actual tipster has an edge. All prices are constant within each scenario so the arithmetic can be independently checked. The point is to provide an audit method an editor or reader can apply to a genuine, timestamped record.

The result in one table: the same 66 winners can go from +15.5% ROI to a loss

Tennis Tips UKOriginal visual research · 15 October 2026

On narrow screens, swipe horizontally to explore the full chart. The exact values are also in the accessible table below.

Assume exactly 120 independent, fully settled pre-match singles match-winner selections: 66 wins, 54 losses, each with one unit staked, no pushes, voids, commission, tax or subscription fees. Every selection in one row uses that row’s decimal odds. Total outlay is 120 units in every case. None of these numbers is drawn from actual matches.

Decimal odds actually obtained	Break-even win rate	Return on 120 units staked	ROI
2.10 (illustrative quoted price)	47.62%	+18.60 units	+15.50%
2.00	50.00%	+12.00 units	+10.00%
1.95	51.28%	+8.70 units	+7.25%
1.90	52.63%	+5.40 units	+4.50%
1.85	54.05%	+2.10 units	+1.75%
1.80	55.56%	−1.20 units	−1.00%

The result changes sign even though the win rate remains 55%. With 66 winners, the exact price needed to break even in this scenario is 120 ÷ 66 = 1.81818…, before other costs. A follower obtaining 1.80 rather than an advertised 2.10 loses 1.2 units on these outcomes. This is a property of the constructed scenario, not a prediction.

How to reproduce every number

• Count only settled win/loss selections in this simple example. Here N = 120, W = 66, L = 54. Separate voids, each-way bets, pushes, exchanges and partially settled markets before extending the formula.
• Win rate = W / N = 66 / 120 = 0.55, or 55%.
• Break-even win rate at constant decimal odds O = 1 / O. For 1.95, that is 1 / 1.95 = 51.282…%.
• Net return in units = W × (O − 1) − L. Equivalently, W × O − N. At 1.95: 66 × 1.95 − 120 = +8.70 units.
• Flat-stake ROI = net return / total stakes × 100. At 1.95: 8.70 / 120 × 100 = +7.25%.
• The break-even odds for a fixed W/N result = N / W; for this illustrative record, 1.81818….

For actual selections at varying odds and stakes, calculate each settled return separately: a winning selection contributes stake × (decimal odds − 1); a losing selection contributes −stake; a fully void selection contributes zero net return while its refunded stake should be treated consistently in the chosen ROI denominator. Sum the net returns; divide by the sum of stakes on settled bets. Keep settlement policies and excluded observations explicit.

A real follower should calculate their own attainable-odds result

The quoted price often reflects a specific publication time, bookmaker, market and potential account limits. It is not evidence that every follower could obtain the same price, at their stake, before the match started. A fair audit records both the price originally recommended and the price actually available or obtained by a follower. Those are two different performance series.

• Record the original publication timestamp and time zone, exact event and players, market, selection, recommended minimum odds, and the accessible bookmaker or exchange.
• Record the subscriber’s receipt time and actual executable price and stake. If the recommended minimum has disappeared, record the missed opportunity rather than silently booking the tip at yesterday’s odds.
• Include every qualifying loss and describe all exclusions. Do not mix moneyline bets, set bets and outrights into one simplified binary formula without adjusting settlement.
• Compare like with like: the same selections, same outcome rules and unit-stake convention at quoted and attainable prices. Disclose any difference in events successfully placed.
• Check for data leakage: picks logged or edited after the event began or after the result became known cannot be treated as contemporaneous forecasts.

A useful record separates the operator-reported yield, the hypothetical flat-stake yield at the originally quoted price, and the follower’s observed yield from bets actually placed. They answer different questions. Comparing only the first and the last without showing missed picks or different stake sizes can distort the conclusion.

Worked fee adjustment: profit on bets can still mean a net loss

Suppose a follower stakes £20 on each of the same 120 hypothetical selections at 1.95, spending £2,400 in total stakes. Their betting result is +8.70 units × £20 = +£174. If following the selections costs an illustrative £20 a month for 12 months, subscription charges total £240, giving a net −£66 before any further charges. Relative to the £2,400 staked, the after-fee result is −2.75%.

The 12-month fee, pick frequency and bet size are assumptions for this example only; they are not Tennis Tips UK’s prices, performance or subscription terms. £240 in fees equals 10 percentage points of this example’s staked turnover. A useful comparison should keep gross betting ROI and after-service-cost return separate.

How confident should we be in a 55% win rate?

We also calculated a two-sided 95% Wilson score interval for 66 wins in 120 Bernoulli trials: approximately 46.1% to 63.6%. We used z = 1.95996 and the standard Wilson formula. The method is documented in NIST’s Engineering Statistics Handbook and the statsmodels proportion-confidence-interval documentation. The interval is a statistical illustration, not a bound on the profit of any real service.

The interval is wide because 120 observations supply limited evidence. In the simple equal-odds setting, even the sign of underlying expected profit cannot be inferred with high confidence from this sample alone at several follower prices. Real tennis selections are not necessarily identical, independent Bernoulli trials: players, events, correlated markets, selection rules and different prices can break those assumptions. A Wilson interval for a pooled win percentage is not a full uncertainty interval for ROI, and it does not correct selection bias or retrospective cherry-picking.

Losing-streak figures require an ordered, date-stamped sequence of individual outcomes; a 66–54 summary has no unique longest losing streak or peak-to-trough drawdown. We have deliberately not invented either statistic. For genuine records, publish time-ordered returns so any reader can reproduce drawdown and time to recovery.

A reusable audit: spreadsheet column layout

For an auditable ledger, use one row per published selection. A minimum schema is below; it is designed for reuse, not as a record of any specific betting company.

Field	What to preserve
Pick ID / publication time	Stable unique identifier and original timestamp with time zone
Event / market / selection	Full player names, tournament, bet type and selection
Quoted odds / minimum odds	Decimal quoted price and stated acceptable minimum
Received time / obtainable odds	Timestamp, independently observed price and bookmaker/exchange
Stake and status	Flat-stake comparison and actual stake; placed, skipped or unavailable
Settlement / net return	Win, loss, void or other result with operator rules recorded
Source / edit history	Link or archive of original published tip and later corrections

For a row with decimal odds in column D, one-unit stake in E and outcome W/L in F, a simple spreadsheet calculation is =IF(F2="W",E2*(D2-1),IF(F2="L",-E2,0)). Use explicit handling for voids and other outcomes and verify your own column choices. Across settled picks, =SUM(return_range)/SUM(settled_stake_range) gives a decimal ROI; format it as a percentage.

Why this is a disclosure standard rather than a winner-finding formula

This method does not estimate a player’s true winning chance, discover a profitable strategy, or demonstrate that one publication is more accurate than another. It tests whether an existing claim remains true under clearly specified, reproducible execution assumptions. A tipster can have a credible rationale for a prediction without a repeatable betting advantage; a profitable published record can be unobtainable for later readers; and a modest negative return over a short window need not prove there is no skill.

For context, OLBG’s tennis tips page surfaces multiple tipster choices and a value rating, while The Grandstand’s daily best bets displays an explicit running record. Those are distinct editorial formats, not data inputs to our calculations. We have not copied or analysed their unpublished pick-by-pick returns, and we make no comparative profitability claim about either site.

This study complements our existing comparison of sports for following tipsters, closing-line value discussion, and tennis betting research and data tools. It isolates one question those pieces raise: will a published return survive a follower-price audit?

Method and limitations

• Publication: 15 October 2026. Calculations are original arithmetic on a wholly constructed 120-pick example: 66 wins, 54 losses, constant one-unit stakes, full binary settlements, no actual event or tipster data.
• Six prices tested: 2.10, 2.00, 1.95, 1.90, 1.85 and 1.80. No bookmaker terms, changes in the available number of bets, taxes, commissions or voids have been modelled in Table 1.
• Subscription-cost illustration: £20 stake on each of 120 bets and £20 monthly fee for twelve months; not a quotation from a service.
• Uncertainty: two-sided Wilson score interval under a common, independent Bernoulli probability assumption. It is not a confidence interval for actual variable-odds ROI.
• No claim of a new observed historical sample, verified backlink, real model accuracy or achievable investment return is made.

Responsible gambling: losses are possible even when estimates suggest an advantage. Never stake money needed for living costs or use this hypothetical exercise as a reason to gamble. The UK Gambling Commission’s consumer guidance explains standards for responsible gambling communications; people who want support can visit GamCare.

Editorial enquiries: This transparent calculation may be quoted or independently reproduced with attribution to Tennis Tips UK and a link to this page. The illustrative results must never be described as actual tennis bet outcomes.