Answers.Body: <p>Duplo bricks manufactured post 2002 are also compatible with a larger brick, produced for a limited time, called Quatro- it is 4 times the size of standard system bricks in every dimension. Older 2x4 bricks were limited by the height of struts between the tubes.</p>
  
  <p><a href="https://i.sstatic.net/yZLF1.jpg" rel="noreferrer"><img src="https://i.sstatic.net/yZLF1.jpg" alt="system, Duplo and Quatro bricks stacked"></a></p>
  
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Answers.CreationDate: 2018-05-14T02:58:50.357Z
Answers.LastActivityDate: 2018-05-14T02:58:50.357Z
Answers.UserDisplayName: Rambling Brick
Answers.Body: <p>Some elements are compatible, others are not. IIRC</p>
  
  <ul>
  <li>You can stack regular 2x2, 2x4 etc lego bricks on top of normal duplo studs and they fit and hold fine. </li>
  <li>You can't cover only part of a stud, so bricks with odd dimensions can't stack completely on top of duplo and 1xn parts can't stack on top of duplo at all.</li>
  <li>Bricks with curved edges are similarly going to be incompatible.</li>
  <li>Thin plates don't have enough depth to take up the taller Duplo stud.</li>
  <li>You can stack Duplo bricks on Lego studs but only the outside of the brick grips the studs which in my experience leads to a relatively weak connection.</li>
  <li>Duplo base plates have studs with flat tops. These are incompatible with Lego.</li>
  </ul>
  
  <p>It seems that the basic Duplo-compatible Lego bricks are a lot less common than they used to be. I just looked at a "Large Creative Brick Box" and found that only about 16% of the contents was traditional Duplo-compatible bricks. Themed sets (including the "Juniors" range ) often contain hardly any.</p>
  
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Answers.CreationDate: 2018-01-02T00:11:10.887Z
Answers.LastActivityDate: 2018-01-05T15:40:53.993Z
Answers.LastEditDate: 2018-01-05T15:40:53.993Z
Answers.UserDisplayName: Peter Green
Answers.Body: <p>Yes! Duplos are 8x the volume of the corresponding Lego bricks.</p>
  
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Answers.CreationDate: 2012-03-23T07:26:51.630Z
Answers.Text: You are correct, but that fact does not prove that they fit together. As **@Joe Wreschnig** say in [his answer](http://bricks.stackexchange.com/a/46/171), many "LEGO-compatible" bricks are not compatible with DUPLO, although they have the same volume (and "outer shape") as a LEGO brick.
Answers.UserDisplayName: awe
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Answers.CreationDate: 2012-02-12T22:58:23.213Z
Answers.LastActivityDate: 2012-02-16T06:59:36.283Z
Answers.LastEditDate: 2012-02-16T06:59:36.283Z
Answers.UserDisplayName: Mookie Wilson
Answers.Body: <p>The answer is: Yes. In fact in my annual project I use a Duplo part that a friend got me from one of the Lego Land parks. Never had a problem using it. </p>
  
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Answers.CreationDate: 2013-03-09T21:04:51.160Z
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Answers.UserDisplayName: JM Kraemer
Answers.Body: <p>Yes, the even by even sized bricks fit to the Duplo studs, can't overhang. Lego plates on top leave a gap. Could overhang from that and add bricks under it, but why bother as it costs more (A 2×2 Duplo brick costs 50p, a 2×4 LEGO System brick costs 19p). Any Lego fits under, but only some Duplo hold with fancy tubes then still not at the corners.
  The Duplo brick's walls have the same thickness as older normal Lego, with ribs.<p>In fact older 2×3 without cross support fit if over hanging, so this just leaving 3 normal Lego studs on the corners not over hanging. A 2:3 slope 3×3 fits when over hanging corner, so could build a roof with eaves.<p><a href="https://i.sstatic.net/3pGBY.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/3pGBY.jpg" alt="Duplo trolley with over hanging bricks" /></a></p>
  
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Answers.UserDisplayName: Andrew Hodson
Body: <p>Can I build a model out of both DUPLO blocks and LEGO blocks? Do they fit together?</p>
  
Tags: <compatibility><duplo>
Title: Are DUPLO blocks compatible with LEGO blocks in any way?
UserDisplayName: fredley
ThreadText: # Are DUPLO blocks compatible with LEGO blocks in any way?
  
  (Asked by: username_0 on 2011-10-25)
  
  Can I build a model out of both DUPLO blocks and LEGO blocks? Do they fit together?
  
  **Tags:** compatibility, duplo
  
  ---
  
  ## 5 answers
  
  ### Answer by username_1 on 2018-05-14. Score: 12
  
  Duplo bricks manufactured post 2002 are also compatible with a larger brick, produced for a limited time, called Quatro- it is 4 times the size of standard system bricks in every dimension. Older 2x4 bricks were limited by the height of struts between the tubes.
  
  [![system, Duplo and Quatro bricks stacked](https://i.sstatic.net/yZLF1.jpg)](https://i.sstatic.net/yZLF1.jpg)
  
  
  ---
  
  ### Answer by username_2 on 2018-01-02. Score: 11
  
  Some elements are compatible, others are not. IIRC
  
  * You can stack regular 2x2, 2x4 etc lego bricks on top of normal duplo studs and they fit and hold fine.
  * You can't cover only part of a stud, so bricks with odd dimensions can't stack completely on top of duplo and 1xn parts can't stack on top of duplo at all.
  * Bricks with curved edges are similarly going to be incompatible.
  * Thin plates don't have enough depth to take up the taller Duplo stud.
  * You can stack Duplo bricks on Lego studs but only the outside of the brick grips the studs which in my experience leads to a relatively weak connection.
  * Duplo base plates have studs with flat tops. These are incompatible with Lego.
  
  It seems that the basic Duplo-compatible Lego bricks are a lot less common than they used to be. I just looked at a "Large Creative Brick Box" and found that only about 16% of the contents was traditional Duplo-compatible bricks. Themed sets (including the "Juniors" range ) often contain hardly any.
  
  
  ---
  
  ### Answer by username_3 on 2012-02-12. Score: 3
  
  Yes! Duplos are 8x the volume of the corresponding Lego bricks.
  
  > **Comments:**
  > **username_4**: You are correct, but that fact does not prove that they fit together. As **@Joe Wreschnig** say in [his answer](http://bricks.stackexchange.com/a/46/171), many "LEGO-compatible" bricks are not compatible with DUPLO, although they have the same volume (and "outer shape") as a LEGO brick.  
  
  ---
  
  ### Answer by username_5 on 2013-03-09. Score: 2
  
  The answer is: Yes. In fact in my annual project I use a Duplo part that a friend got me from one of the Lego Land parks. Never had a problem using it.
  
  
  ---
  
  ### Answer by username_6 on 2023-02-14. Score: 1
  
  Yes, the even by even sized bricks fit to the Duplo studs, can't overhang. Lego plates on top leave a gap. Could overhang from that and add bricks under it, but why bother as it costs more (A 2×2 Duplo brick costs 50p, a 2×4 LEGO System brick costs 19p). Any Lego fits under, but only some Duplo hold with fancy tubes then still not at the corners.
  The Duplo brick's walls have the same thickness as older normal Lego, with ribs.
  
  In fact older 2×3 without cross support fit if over hanging, so this just leaving 3 normal Lego studs on the corners not over hanging. A 2:3 slope 3×3 fits when over hanging corner, so could build a roof with eaves.
  
  [![Duplo trolley with over hanging bricks](https://i.sstatic.net/3pGBY.jpg)](https://i.sstatic.net/3pGBY.jpg)
  
  
  ---
  
  