What is DRS in Cricket? Complete Guide 2026

Picture the scene. India are playing Australia in a high-stakes Test match. Jasprit Bumrah thunders in and delivers a full-length ball that crashes into the Australian captain's pad. Bumrah screams in appeal, the on-field umpire raises his finger — out. But the batsman pauses, consults his partner for a second, then turns to the dressing room and forms a large letter T with his hands and forearms.

The crowd roars. The third umpire gets involved. Technology takes over. And thirty seconds later, the decision is overturned — the ball was going over the stumps.

That T sign is DRS. And it has fundamentally changed cricket.

This guide explains every aspect of the Decision Review System — what it is, how the technology works, how many reviews each team gets, what "umpire's call" actually means, and how top teams use DRS as a strategic weapon.

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What is DRS in Cricket?

DRS stands for Decision Review System. It is a technology-based process that allows players to challenge on-field umpiring decisions in international cricket. When a team believes the on-field umpire has made an incorrect decision — either giving a batsman out when they should not be, or not giving them out when they should — the batting or fielding team can call for a review.

The DRS is managed by the third umpire, who sits off the field with access to multiple camera feeds and specialist technology systems. The third umpire reviews the available evidence and either upholds the on-field decision or overturns it.

A brief history: DRS was first piloted in a Test match between India and Sri Lanka in October 2008 in Colombo. After refinements over the following two years, the ICC formally adopted DRS for all full-member international matches in 2011. It has been mandatory in Tests and bilateral ODIs since, though its implementation in multi-team tournaments and domestic cricket has varied by governing body and year.

One notable early resistance came from India, whose cricket board (BCCI) initially objected to DRS, citing concerns over the accuracy of Hawk-Eye ball tracking. India only accepted the full DRS — including ball tracking — for bilateral series from 2016 onwards. Before that, some India series used a "UDRS minus Hawk-Eye" version, which was controversial and widely criticised.

Today, DRS in its full form is used in Tests, ODIs, and T20 Internationals across all ICC Full Member nations.

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The 3 Technologies That Power DRS

DRS is not a single piece of technology — it is a combination of three specialist systems working together. Each answers a different question.

Ball Tracking (Hawk-Eye)

Hawk-Eye is the technology that tracks the exact path of a cricket ball from the moment it leaves the bowler's hand to the moment it reaches the batsman. It uses multiple high-speed cameras positioned around the ground — typically six — to capture the ball's position at hundreds of points per second. A computer algorithm then reconstructs the complete 3D trajectory of the ball and, critically, predicts where the ball would have gone if the batsman's leg had not been in the way.

This predictive element — the virtual projection of the ball's future path — is what makes Hawk-Eye so important for LBW decisions. When a batsman is struck on the pad and an LBW appeal is made, Hawk-Eye shows whether the projected path of the ball would have hit the stumps, go over the top, or pass outside leg stump.

The output is that famous "cone" — a tapering triangular shape showing the predicted impact zone on the stumps. If the cone fully hits the stumps, the batsman is out. If it clips the edge of the stumps (what is called "umpire's call" territory), the on-field decision stands. If it misses entirely, the batsman is not out.

Suggested diagram: ball-tracking cone diagram showing ball pitch, impact point, and predicted path cone relative to stumps.

UltraEdge (Snickometer)

UltraEdge — sometimes called the Snickometer or simply "snicko" — detects whether the cricket ball made contact with the bat or glove as it passed the batsman. It does this by combining two data streams: the audio feed from a microphone positioned on the stumps (or close to the pitch area), and the video of the bat passing through the frame.

The technology displays a waveform — a visual representation of sound — on the third umpire's screen. If the waveform spikes at the exact moment the ball passes the bat, that spike indicates contact. Crucially, UltraEdge can distinguish between ball-on-bat and ball-on-pad, because the sound characteristics of leather hitting willow are different from leather hitting protective equipment.

UltraEdge is used primarily for caught-behind decisions and snick-to-slip catches where the umpire is unsure if the bat was involved. If UltraEdge shows no spike, it is strong evidence the ball did not touch the bat.

HotSpot (Infrared Imaging)

HotSpot uses infrared cameras to detect heat generated by friction. When the ball makes contact with any surface — bat, glove, pad, helmet, ground — it generates a tiny amount of heat at the contact point. HotSpot's infrared cameras capture this heat signature as a bright spot on the image.

HotSpot is particularly useful for distinguishing thin edges and for cases where a ball appears to have hit the bat but UltraEdge shows no spike (or vice versa). It can reveal contact that is invisible to the naked eye or to standard cameras.

However, HotSpot has one known limitation: it requires a temperature differential to show a mark. In cold conditions, or when the ball is wet, the friction heat can dissipate too quickly to register. HotSpot is also not universally deployed — it is expensive to install and is not available at every ground. When it is not available, DRS proceeds with ball tracking and UltraEdge only.

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How Many Reviews Does Each Team Get?

Each team has a limited number of reviews per innings. The allocation depends on the format:

Format	Reviews per team per innings	Reviews retained on "umpire's call"
Test matches	2	Yes
ODI matches	2	Yes
T20 Internationals	1	Yes

The key rule about retaining reviews: If a team reviews a decision and the third umpire's verdict is "umpire's call" (explained in detail in the next section), the team does NOT lose their review. They get to keep it. A review is only lost when the on-field decision is fully upheld — meaning the technology shows clearly that the original umpire was correct.

In Test matches, where a team has 2 reviews and each innings can last for an entire day or more, review management becomes a genuine tactical skill. A team that burns both reviews early on questionable LBW shouts has no protection for the rest of the innings if a genuinely bad decision goes against their best batsman.

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What is "Umpire's Call"?

Umpire's call is the single most misunderstood concept in DRS — and the one that generates the most post-match argument on social media and in commentary boxes.

Here is the core principle: the on-field umpire's decision stands unless the ball-tracking technology shows the ball was clearly going to miss the stumps or clearly struck the stumps. If the ball is only clipping the edge of the stumps — in the grey zone — the original decision is not overturned.

The specific rules for umpire's call are:

For LBW — impact on the stumps: Hawk-Eye identifies the predicted impact zone of the ball on the stumps. The stumps are divided into three segments: the top half, the bottom half and the sides. If more than 50% of the ball is hitting the stumps in the predictive projection, the batsman is out. If less than 50% is hitting the stumps — a marginal clip — it is umpire's call on impact. The on-field decision stands.

For LBW — pitching: If the ball pitches in the grey zone near the edge of the crease, Hawk-Eye may declare umpire's call on pitch. Again, the on-field decision stands.

Why does umpire's call exist? Because no technology is 100% accurate. Hawk-Eye operates with a margin of error of approximately 2.5mm for LBW predictions. That may sound tiny, but at the fine margins where balls clip the edge of the stumps, a 2.5mm error is the difference between out and not out. The ICC's position is that within that margin of uncertainty, the human umpire's on-field judgement should be respected.

A real example: In the 2020-21 Border-Gavaskar Trophy, there were multiple instances where a ball was shown to be clipping the top of the stumps and the crowd and commentators assumed a review would succeed — only for the verdict to come back "umpire's call, decision stands." When the on-field umpire had said not out, the batsman survived. When the umpire had said out, the batsman was gone. Same ball trajectory, different result, depending purely on the original call. This is the feature that drives fans and players to distraction — and it is entirely by design.

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Step-by-Step: What Happens When a Team Reviews

Here is exactly what unfolds from the moment a captain signals a review to the moment the decision is announced.

Suggested diagram: review process flowchart showing each step below.

Step 1 — The signal. The batting or fielding captain (or, in the batting team's case, the batsman themselves) forms a large T shape with their forearms and hands. This is the universal DRS signal. They must signal clearly and immediately after the on-field umpire makes the decision.

Step 2 — The 15-second window. Once the on-field umpire gives their decision, the team wishing to review has 15 seconds to signal. This is why you often see batsmen look at their captain or the dressing room for a signal — sometimes information about a potential edge or ball-tracking issue comes from the dressing room analyst watching replay screens, and a quick exchange needs to happen inside 15 seconds.

Step 3 — The third umpire takes over. Once the review is confirmed, the on-field umpires signal to the third umpire's room, and play stops. The third umpire now has access to all available technologies: slow-motion camera replays, Hawk-Eye projection, UltraEdge waveform, and HotSpot imaging (if available).

Step 4 — Technology checks, in sequence. For an LBW review, the third umpire checks: (1) did the ball pitch in line? (2) did the ball hit the bat before the pad? (3) where did the ball impact the pad? (4) what does Hawk-Eye project for the ball's path? Each question can end the review early — if the ball pitched outside leg stump, for instance, the review is over immediately (not out, regardless of everything else).

Step 5 — Decision communicated. The third umpire announces the verdict via earpiece to the on-field umpires. The on-field umpire then signals the decision to the scorers and players — either repeating the original signal (upheld) or reversing it with the appropriate new signal (overturned).

Step 6 — Review count updated. If the review was successful (decision overturned) or if the result was umpire's call, the reviewing team keeps their review count. If the review was unsuccessful (original decision upheld by clear evidence), the team loses one review.

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When Should You Review? Strategic Thinking in DRS

Top international teams treat DRS reviews as a precious resource, especially in the second innings of a Test where both reviews may need to last 90+ overs. Here is how elite teams think about the decision to review:

Review for LBW — consider three factors. Was the ball bowled on the stumps (not angling well down leg)? Did the ball not hit the bat? Did the ball pitch in line with the stumps? If all three are yes, a review is almost always worth taking. If any one of the three is doubtful, the chances of a successful review drop sharply.

Review for caught-behind — consider the UltraEdge. Batsmen who genuinely know whether they edged a ball are in the best position to review. A batsman who felt no contact but the umpire has given them out should review almost every time. A batsman unsure whether they hit it should hesitate — if UltraEdge shows a spike, the review will fail.

Protect your best batsmen. In Test cricket, teams often save at least one review for their most important batsmen. Burning two reviews in the first hour on marginal calls against a number-nine batsman leaves the team defenceless if a top-order player is given out LBW when they clearly hit the ball.

Late-innings pressure. In a T20 or ODI chase, a team chasing a total will typically use their single review aggressively to protect any set batsman. A top-order batsman who has 30 runs off 20 balls is far too valuable to lose to a bad decision.

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DRS Controversies and Famous Failures

No technology is perfect, and DRS has had its share of high-profile controversies.

The Ashes 2019 — umpire's call storms. Several decisions during the 2019 Ashes series reignited debate about umpire's call, with both England and Australia losing batsmen to balls that showed Hawk-Eye clips as clipping the very top of the stumps. The resulting "out — umpire's call" verdicts felt arbitrary to many observers, since if the umpire had originally said not out, the batsman would have survived.

India's initial opposition (2008-2016). The BCCI's long resistance to full DRS was one of the most politically contentious issues in cricket administration for nearly a decade. India's concerns centred on the accuracy of Hawk-Eye's ball-tracking predictions. Critics, particularly from other boards, argued India's real concern was that DRS would remove the home umpiring advantage that teams could exploit in certain bilateral series. India eventually adopted full DRS in 2016, and the controversy largely subsided.

Hot weather and HotSpot failures. There have been documented cases — particularly in subcontinental conditions — where HotSpot failed to register genuine bat edges because the ambient heat reduced the contrast of the friction mark. These incidents led to HotSpot being used more cautiously as a definitive tool and more often as corroborating evidence alongside UltraEdge.

The 2019 World Cup final — no DRS on run-out. In the extraordinary 2019 ICC Cricket World Cup final between England and New Zealand, a controversial run-out deflection off Ben Stokes's bat in the final over could not be reviewed via DRS because run-out decisions in that tournament format used different review protocols. That incident had nothing to do with DRS technology but demonstrated how review system boundaries and limitations can affect high-stakes outcomes.

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DRS in IPL

One of the most common misconceptions about DRS is that it is not used in the IPL. That was true in earlier IPL seasons, but the BCCI introduced DRS into the IPL from IPL 2018 onwards.

In IPL, the DRS rules are:

• Each team gets 2 reviews per innings
• Reviews are lost if unsuccessful (umpire's call still retains the review, as per standard ICC rules)
• All three technologies — Hawk-Eye, UltraEdge and HotSpot (where available at the ground) — are used
• The third umpire process is identical to international matches

The reason DRS was introduced to IPL later than international cricket was primarily cost and logistics — equipping eight to ten IPL venues with full Hawk-Eye, UltraEdge and HotSpot infrastructure takes significant investment. Since 2018, DRS has been a standard part of IPL broadcasting and on-field officiating, and fans at home and in the ground see the same ball-tracking and edge-detection graphics as in any international match.

So the next time you watch an IPL game in 2026 and see a captain make the T signal — yes, DRS is fully in play.

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Quick Reference: DRS Rules Summary

Rule	Detail
Reviews per team in Tests	2 per innings
Reviews per team in ODIs	2 per innings
Reviews per team in T20Is	1 per innings
Reviews per team in IPL	2 per innings
Review signal	T shape formed with forearms and hands
Time window to review	15 seconds after on-field decision
Review retained?	Yes, if result is "umpire's call"
Review lost?	Yes, if original decision fully upheld
Technologies used	Hawk-Eye (ball tracking), UltraEdge (snickometer), HotSpot (infrared)
Who manages DRS?	Third umpire, off-field
When introduced (pilot)?	2008 (India vs Sri Lanka, Colombo)
When fully adopted by ICC?	2011
India full DRS adoption?	2016
IPL DRS introduced?	IPL 2018 season

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Frequently Asked Questions About DRS

Can a bowler ask for a review, or only the captain? In practice, the fielding team's review is always called by the captain or the bowler themselves. Any fielding player can theoretically initiate the T signal, but convention and playing conditions in most formats require that a review be called by the captain. For the batting side, the batsman who has been given out is the one who signals the review — sometimes after a very quick glance at their captain or dressing room.

What happens if a team has no reviews left but gets a clearly wrong decision? The decision stands. Once a team's reviews are exhausted, there is no recourse for the rest of that innings regardless of how bad an umpiring mistake may appear. This is why saving reviews strategically matters so much in Test cricket.

Can DRS be used to review a no-ball? No — DRS cannot be used by players to review a no-ball call (front-foot no-ball). However, the ICC has trialled a system in some series where the third umpire checks every delivery for front-foot no-balls independently, removing the reliance on the square leg umpire. This is not the same as DRS review but is part of the broader technology ecosystem in modern officiating.

Does DRS apply to all dismissal types? DRS can be used for LBW decisions, caught-behind decisions, bat-pad catches, and whether a catch was taken cleanly. It is also used to check whether the ball carried to the fielder (did not bounce before being caught). It cannot be used for run-outs — those are referred directly to the third umpire by the on-field umpires, not via a team review.

What is the difference between DRS and a third umpire referral? A DRS review is initiated by a player (the captain or batsman) and uses the full technology suite. A third umpire referral is initiated by the on-field umpire — typically for boundary line decisions, disputed catches near the rope, and run-outs. The third umpire is involved in both, but only the player-initiated DRS process counts against a team's review allocation.

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Conclusion

DRS has made cricket fairer — not perfect, but measurably better. The number of clear errors that survive an innings has dropped significantly since full DRS adoption in 2011. Ball-tracking, UltraEdge and HotSpot together give the third umpire a level of information no on-field umpire standing 22 yards away could possibly have.

The controversy over umpire's call will never fully go away — it is baked into the system's philosophy that technology should only override human judgement when the evidence is unambiguous. When the ball is clipping the stumps at the margin of what technology can reliably predict, the man standing in the middle still gets the final word.

For anyone following cricket rules, understanding DRS is essential — it affects dozens of decisions in every series and is central to post-match analysis and commentary. The next time you see the T sign raised and the crowd holds its collective breath, you will know exactly what is being checked, how long it should take, and what each possible outcome means.

If you enjoy tracking how DRS decisions and other match events affect team standings, our NRR Calculator is a useful tool to understand the net run rate implications of any result.

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Sources:

• ICC Playing Conditions — Decision Review System
• Hawk-Eye Innovations — Cricket Ball Tracking
• ESPNcricinfo — DRS Explainer
• BCCI — IPL DRS Implementation Guidelines