--- title: "Fill Ratio: Formula, Meaning & Signals" description: "Fill ratio is the number of orders that were filled divided by the number of orders submitted. Unlike fill rate, it counts orders rather than quantity." canonical: https://www.getswoopr.com/indicators/market-microstructure/fill-ratio/ source: "Swoopr Investment: https://www.getswoopr.com" --- ## Direct Answer > Fill ratio is the number of orders that were filled divided by the number of orders submitted. Unlike fill rate, it counts orders rather than quantity. A low ratio is expected for passive strategies that place many limit orders and expect most not to execute; a high ratio is expected from marketable orders. # Fill Ratio: Formula, Meaning, Signals, Examples and How to Use It ## How Is Fill Ratio Calculated? Fill ratio is the number of orders that were filled divided by the number of orders submitted. Unlike fill rate, it counts orders rather than quantity. **Formula:** `Fill Ratio = number of orders filled / number of orders submitted` **Inputs:** - Count of filled orders - Count of submitted orders - Definition of filled (fully, or partially) **Worked example.** 340 filled orders out of 500 submitted give a fill ratio of 68.0%. The inputs are illustrative numbers, not market data. **Reading it.** A low ratio is expected for passive strategies that place many limit orders and expect most not to execute; a high ratio is expected from marketable orders. It is a behavioral statistic about a strategy and venue, not a measure of quality on its own. **Limits.** Whether a partial fill counts as filled changes the result, and the ratio treats a 100-share order the same as a 100,000-share order. It can differ greatly from the quantity-based fill rate on the same orders. ## What is Fill Ratio? Fill ratio is the number of orders that were filled divided by the number of orders submitted. Unlike fill rate, it counts orders rather than quantity. ## How to use Fill Ratio A low ratio is expected for passive strategies that place many limit orders and expect most not to execute; a high ratio is expected from marketable orders. It is a behavioral statistic about a strategy and venue, not a measure of quality on its own. A reading alone is never a buy or sell signal; it needs context from price structure, volume, volatility and the broader market regime. ## Strengths - Counting orders instead of shares gives an easy read on how often an instruction completes, regardless of how big each one was. - It is simple to compute from an order log with a status column, requiring no price or market data at all. - Reproducible when the formula and data convention are fixed. ## Weaknesses and limitations - It can be raised by submitting many small, easily filled orders, so a high ratio can reflect order design rather than venue quality. - An order that fills a minute after the window closes counts as unfilled, so the ratio depends on the observation cutoff. - Correlated indicators can create false confidence by repeating the same underlying information. ## Editorial and risk note This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance. ## Frequently Asked Questions Is Fill Ratio a buy or sell signal? No. A low ratio is expected for passive strategies that place many limit orders and expect most not to execute; a high ratio is expected from marketable orders. Whether a partial fill counts as filled changes the result, and the ratio treats a 100-share order the same as a 100,000-share order. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions. What is the best setting for Fill Ratio? Fill Ratio is computed from count of filled orders; count of submitted orders; definition of filled (fully, or partially), so the choices that matter are the data convention and the window it is read over. Test those across instruments, regimes and out-of-sample periods instead of fitting one historical winner. Can Fill Ratio be used by itself? Whether a partial fill counts as filled changes the result, and the ratio treats a 100-share order the same as a 100,000-share order. It can differ greatly from the quantity-based fill rate on the same orders. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone. Does Fill Ratio work on every timeframe? The calculation (Fill Ratio = number of orders filled / number of orders submitted) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it. Why does Fill Ratio give false signals? It can be raised by submitting many small, easily filled orders, so a high ratio can reflect order design rather than venue quality. An order that fills a minute after the window closes counts as unfilled, so the ratio depends on the observation cutoff. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated. How should Fill Ratio be backtested? Rebuild Fill Ratio from count of filled orders using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline. S Swoopr Editorial Team The Swoopr Editorial Team produces independent investment education, research, and tools for understanding markets, evaluating opportunities, and managing risk. All content is educational only and does not constitute personalized investment advice. See our [editorial policy](https://www.getswoopr.com/legal/editorial-policy/) and [corrections policy](https://www.getswoopr.com/legal/corrections-policy/).