How Dropping Odds Are Calculated – Formula and Pitfalls

Dropping odds are calculated as the fall from an earlier price to the current price: drop % = (earlier odds − current odds) ÷ earlier odds × 100, so 2.10 to 1.90 is a 9.5% drop. The formula is the same everywhere. What changes the answer is the earlier price a tracker uses (the opener, the start of a time window, the recent high or a market average) and whether it reports price percent or probability points, with or without the margin. On 1 November 2026, those choices made one La Liga match show a 19% drop on one public tracker and a drift on another.

If you use a dropping-odds list to decide what to bet, you need to know which of these choices it made. This page explains each one with real prices, shows how far apart the results can be, and says which measure fits which question. For what dropping odds are and why they happen, start with what are dropping odds.

Definition. A dropping-odds calculation compares a current price with one earlier reference price for the same selection. It has four parts: the reference price (opener, window start, recent high or average), the source (one bookmaker or an average of several), the unit (percent of the price or implied-probability points) and the margin treatment (raw prices or fair prices with the margin removed).

What is the formula for dropping odds?

There are three common ways to express the same move. Take a price that falls from 2.10 to 1.90:

Most free lists sort by the first. Trackers that rank by how far opinion moved, such as SteamWatch and Football Park, use the second. The odds drop calculator gives the price drop and the probability change for any pair of prices.

Why do price percent and probability points disagree?

Because the same percentage fall means very different things at different prices. A long price can fall a lot in percent while the implied chance barely moves:

Calculated by us. A list sorted by price percent puts the 21.00 outsider first. A list sorted by probability points puts the 2.10 favourite first, because that is where more of the market's opinion changed. Football Park makes the same point on its own page with the 21.00 → 15.00 example (read 1 November 2026). For value betting, points are the better unit: the edge on a bet is a difference between probabilities, not between prices. More on the conversion in implied probability explained.

Which earlier price does each tracker use?

This is the choice that changes results most. Five public examples, each described in the tracker's own words:

SteamWatch, Football Park and OddsSafari read 1 November 2026; Oddspedia read 30 October 2026. More free trackers are compared in free dropping odds sites.

Each reference answers a different question:

• The opener answers "how far has this price travelled since it was first posted?" It includes the opening correction, which is large because opening margins are wide; see when do odds open.
• A fixed window (48 hours, 6 hours, 1 hour) answers "what moved recently?" The shorter the window, the fresher the move.
• The recent high answers "is this price falling now, from its latest peak?" It separates a new fall from a price that is only returning to where it opened.
• A market average answers "has the market as a whole moved?" It moves only after enough bookmakers have moved, so it trails the first mover.

One match, four different answers

Athletic Bilbao v Real Sociedad, La Liga, 1 November 2026 (kick-off 20:00 UTC). All prices read on public pages between about 18:45 and 18:55 Madrid time (CET), when the last Pinnacle snapshot on SteamWatch was from 17:35 UTC:

Price changes and points calculated by us from the published prices.

The same home team is drifting or dropping depending on whether you start two weeks ago or two days ago. The Athletic price rose from 1.82 to at least 2.17 and then came part of the way back. A tracker that measures from the opener calls it a drift; one that measures over 48 hours calls it a drop; Pinnacle Terminal would label a price heading back towards its opener a Rebound, not a new drop.

The away side shows the source effect. Measured on Pinnacle alone, Real Sociedad shortened 8.7%. Measured on an average of bookmakers that opened longer, at 4.44, it shortened 19%, more than twice as much. Neither number is wrong. They describe different prices. The full La Liga picture for that week is in La Liga dropping odds.

Why should you remove the margin first?

Because the margin shrinks as kick-off nears, and a shrinking margin shortens prices with no change in opinion. On the same match, Pinnacle's 1X2 margin was about 6.4% at the opener (1.82 / 3.66 / 4.15) and about 2.75% on match day (2.03 / 3.69 / 3.79). Removing it with the power method (our calculation):

With the margin removed, Real Sociedad's chance rose by half as much again as the raw prices suggested. To devig any market, use the devig calculator; Power is the default method in Pinnacle Terminal. Football Park strips the margin before it ranks rows for the same reason (its page, read 1 November 2026). Why a margin exists and how it is split between outcomes is in overround, vig and margin explained.

Opener or recent high: why does it matter for a Sharp drop?

Because a price can fall a long way from its high while sitting near its opener. An illustrative example, not a real market: a price opens at 2.00, drifts to 2.40, then falls to 1.95.

A list based on the opener shows almost nothing. Measured from the high, the price has just fallen close to 20%. In Pinnacle Terminal, a Sharp drop is a fall of about 20% or more from the recent high (an approximate size, not a hard cutoff), such as 3.00 to 2.40. And a price that has only returned to its opening level is a Rebound: see odds rebound after a drop.

How fast did it fall?

None of the formulas above contains time, and time is what decides whether a drop is still useful. A 9.5% fall from 2.10 to 1.90 over three days is a drift your bookmaker has probably already matched. The same fall inside two minutes is a move that slower bookmakers may not have copied yet. SteamWatch, for example, records the time of the largest single step on each match page; on Athletic Bilbao v Real Sociedad it was 11:04 UTC on 1 November. A short measuring window catches the move while it happens; a 48-hour or opener comparison reports it afterwards. How quickly other bookmakers follow is discussed in why dropping odds alerts don't convert.

Which calculation should you use?

Match the measure to the question:

1. "Is there value at my bookmaker right now?" Use Pinnacle's current fair price, not any drop figure. Compare your price with it in the EV calculator.
2. "What is moving right now?" Use a short window on one sharp source, measured from the recent high.
3. "How far has the market moved this week?" Use the opener, devigged on both sides, in probability points.
4. "Has the whole market moved, or only one book?" Compare one sharp source with an average.
5. "Did I beat the market?" Use the closing line, not a drop: compare your odds with the fair closing price in the CLV calculator.

How Pinnacle Terminal handles this

The terminal reads Pinnacle's live feed and compares the current price with the price at the start of a window: 2 minutes by default, which you can widen or narrow. A Sharp drop is sized from the recent high. It does not stop at the size of the fall: each pre-match move gets a 0–10 grade and one label that adds what a percentage cannot show. Big move: the price dropped and Pinnacle closed the market. Sharp drop: roughly 20% or more from the recent high. Limit-backed: the price dropped and Pinnacle raised its maximum market limit. Rebound: the price is returning towards the opener. Downtrend and Standard cover slower and smaller moves. Live in-play football drops are shown as they happen and filtered by match context, without a grade. Each alert goes to your own Telegram bot with the fair price (Power devig by default). The terminal works on live prices and keeps no odds history, so for a week-long comparison from the opener a historical tracker is the right tool. Full feature list: Pinnacle dropping odds.

FAQ

How do you calculate the percentage drop in odds?

Subtract the current odds from the earlier odds and divide by the earlier odds, then multiply by 100. From 2.10 to 1.90: (2.10 − 1.90) ÷ 2.10 × 100 ≈ 9.5%.

How do you convert an odds drop into probability?

Take 1 ÷ current odds minus 1 ÷ earlier odds. From 2.10 to 1.90, the implied probability rises from 47.6% to 52.6%, a change of 5.0 percentage points. Remove the margin first for a fair comparison.

Why do two dropping-odds sites show different drops for the same match?

They use a different earlier price or a different source. On Athletic Bilbao v Real Sociedad (1 November 2026), Real Sociedad had shortened 8.7% on Pinnacle since the opener and 19% on an average of bookmakers that opened at a longer price.

Is a 20% drop in odds big?

It depends on the price and the reference. 5.00 to 4.00 is a 20% drop but 5.0 probability points; 2.10 to 1.80 is a 14.3% drop but 7.9 points. Pinnacle Terminal calls a fall of roughly 20% or more from the recent high a Sharp drop.

Should dropping odds be measured from the opening price?

Only to see how far a price has travelled overall. The opener includes the wide opening margin and the early correction. To see what is moving now, measure from the recent high or over a short window.

Sources

• steamwatch.io/dropping-odds ("How SteamWatch measures a drop", list rebuilt 17:48 UTC) and the Athletic Bilbao v Real Sociedad match page (last snapshot 17:35 UTC), read 1 November 2026 at about 18:50 CET.
• oddssafari.com/dropping-odds/sports/10 (method note and La Liga row), read 1 November 2026 at about 18:50 CET.
• footballpark.com/betting/follow-the-money (method, bet365 prices checked 17:30 GMT), read 1 November 2026.
• oddspedia.com/dropping-odds, read 30 October 2026.
• Percentages, probability points and fair prices (power method): our own calculation from the prices above.

Try it

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