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If this in any way scares you then try a "mock" math trade, see
Mock Math Trades - Learn to be a math trader

(This wiki entry is based on Lindsey's guide from Math trade guide.)

Math trades are a very good way to swap games with other people on BoardGameGeek. But with all the posts in your average trade, they can be hard to follow if you're new to them. I've tried here to describe how to (and whether to) participate in math trades, and hopefully to take care of any confusion about them.

If, on the other hand, you're interested in running a math trade, see the OLWLG For Organizers article.

What is a math trade?

This is a trade between a whole bunch of people at once, using an algorithm (such as used by TradeMaximizer) to decide who should send their game to whom. Because of the algorithm used, you can only get a game you prefer over what you started with. (Or at worst, you may just keep your original game; i.e. it doesn't trade.)

This kind of trade was originally called a "mathematical no-risk trade list." Today, it's simply known as a math trade.

In a math trade, any potential trades found are always going to be "1 for 1" which is one of your offering(s) that you will ship out (or deliver if it's a "no ship") to another participant in the math trade. You will receive exactly one offering (from your "want list" for your offering) from most likely yet another participant. An "offering" is a single geeklist item, but the offering/item could be a bundle of more than one thing.

Why is a math trade worthwhile?

By matching together the likes and dislikes of a lot of people at the same time, many more trades become possible. Say person A wants the game Queen's Necklace, and person B has a copy of it for trade, but person B doesn't want any of A's games and would instead like a copy of Jambo. Person C has Jambo for trade, but doesn't want any of B's games. But C would like Razzia, which person A is interested in trading. Although there's no good trade between two of A, B, and C, the three together can each trade a game away to get a game they really want. The math trade algorithm figures out these fortunate coincidences, and assigns trades so that everyone gets games they want in return for trading away games they don't. In the above example you would have these trades:

A sends Razzia to C, and gets Queen's Necklace from B
B sends Queen's Necklace to A, and gets Jambo from C
C sends Jambo to B, and gets Razzia from A

A circle of trades takes place among the participants and everyone gets a favorable trade.

Like any kind of game trade, this depends mostly on differing tastes. As shown by the many debates here about the "best" games, each person has different preferences and it's quite possible for everyone in a trade to be very happy with the outcome. Because of this, math trades are often a great way to get a hard-to-find game, since one person's old, forgotten game could be your personal treasure.

If you like learning about games, math trades also give you a good reason to find out about a lot of games you might not otherwise have seen. If you just want to trade for games you already know about, though, you can still participate in a math trade without any difficulty -- just ignore the games you've never heard of.

Cash Value Trades in Math Trades

Any Math Trader who accepts a cash value trade (a numerical amount via gift card, gift certificate, PayPal, actual cash, etc.) is conducting a direct sale through the site and is subject to the associated commission fee (3%) required by the Terms of Service just as with any other sale.

After the trade, the person receiving the GC/PayPal/cash creates a Geek Market listing, and the person sending the GC/PayPal/cash buys it.

For a step-by-step guide, please see this thread.

How does it work?

When someone is willing to moderate a math trade, they start a trade GeekList. In the GeekList, they'll tell you the rules of that particular math trade. Since the rules differ a bit from list to list, you need to read them carefully. Though the rules can differ a little, most parts of a math trade stay the same between lists:
  • The moderator posts a trade GeekList, along with any rules for that math trade.
  • Everyone interested in joining the trading posts the game(s) they'd like to trade as items in the GeekList.
  • At some point (which is usually mentioned in the rules at the start of the GeekList), the math list is closed to new game entries.
  • Everyone who submitted a game then figures out which games they'd like from the list. They submit a list of wants for each game they put up for trade in the geeklist. These wants are submitted to the moderator, typically by using the OLWLG tool, which automates the process of collecting want lists for all the users.
  • Once the moderator has everyone's lists of wanted trades, they run the algorithm to find out who should send their game to whom. This algorithm is typically configured to maximize the total number of trades.
  • The moderator posts the list of trades as decided by the algorithm. Some game entries won't be traded at all. For the rest, you'll be told whom to send your game to and which game you'll be getting in return (and from whom). Unlike direct trades, you'll probably be getting your new game from a different person than you sent your old game to.
  • Often, the moderator will ask that everyone wait a little while (perhaps overnight) to make sure there weren't any mistakes when running the algorithm.
  • The traders then contact each other. The best way to take care of things is usually with BoardGameGeek's Trade Manager. Just send a trade request to the person to whom you'll be sending a game (and/or to the person who will be sending a game to you). This automatically sends your mailing address, and (most importantly) lets people leave feedback after the trade.
  • Once you know where to send your game, mail it (hopefully fairly quickly) to its recipient. In most math trades, the kind of shipping has been up to the sender. It's best if you keep in contact with the other trader, so they'll know about any delays or problems.

Differences between math trades

The moderator chooses the rules of the math trade, and if necessary, decides on any problems which come up. Math trades so far have all been pretty similar, but some details have differed. Specifically ...
  • Type of entries: The vast majority of math trades allow board games as entries. Many will also allow other types of items, either as entries or as "sweeteners" (items added in addition to the original entry). Other item types include gift cards, geekgold, video games, DVDs, and so forth.
  • Deadlines: Some math trades leave lots of time for entries, others are quick. Some math trades leave a long time for everyone to turn in their lists of desired trades, while others have a short time. Be very sure to read and consider these deadlines! If you aren't going to have the time to choose between trades, you should wait for another opportunity.
  • Location of traders: Some lists will limit participation to people in the US, or Canada, or some other country or group of countries. Special "no ship" math trades are often run for people to meet in person, typically at a convention or for people residing in or near a city.
  • Allowable games: In some lists, the moderator will only allow games which have a specific rating average on BoardGameGeek, or number of people who have listed it as "wanted", or some combination of the two. There have even been lists only for games with less than a certain number of people listing it as "wanted". In a math list with multiple items in the same entry ("sweeteners"), the limit may apply to all games in the entry, or only to the first game listed. It's likely that moderators will continue to come up with other, new criteria (such as "wargames only") to limit the games for trade.

What can go wrong?

And how can I avoid any problems?
So you can trade a game you don't want for one you do! That's great, but it's important to understand the risks involved.
  • Be sure to consider shipping and packaging costs when you choose the games you'd like to trade for! Especially if you're trading away a very heavy game, shipping can easily exceed $10. Even if the game you're trading is worthless to you, you shouldn't trade it away for a game worth less than the cost of shipping.
  • Make sure your list of wanted trades is correct! If you list the wrong game entry as one you're willing to trade for, you could get stuck trading for something you don't want! If you made a mistake in your list of wanted games, and ended up with a game you didn't really want, there is at least one trick which can reduce the problem. You may be able to persuade the person who would have sent you the game instead to hold it for you for later trades. You can then trade the game to someone else for something you really want, and have the original owner send it for you.
  • Be careful about addresses! If you accidentally send your game to the wrong person, you'll need to pay to have it sent to the correct address. Similarly, be sure you have your address correct when giving it to the sender!
  • Communicate clearly and quickly! Be sure to give an accurate description of the game you're trading, and contact the people you're trading with if there are any problems which come up. And if you have any question about another person's game entry, do ask them (in the GeekList) for more detail.
  • Be patient! Do not send your game immediately after the trades have been listed by the moderator. Instead, wait about a day for any issues to be raised.
  • Only trade your game in one place at a time! If you offer the same game in two separate trade lists, or have your game listed for sale on BoardGameGeek at the same time you have it in a math list, you can end up obligated to send your game to two people at the same time.
  • "Deadbeat" traders: The worst possible problem in any trade is that the other person just doesn't send their game. In that case, it is important to try to communicate with them, and show some patience -- many people on BoardGameGeek are very busy with events other than playing games. But it is possible there will be a problem even after trying to communicate. As with other trades, you can (if you used the trade manager) leave appropriate feedback for the trade. If absolutely necessary, you may want to consider listing the trader as "deadbeat." There is a trade GeekList for the listing and discussion of deadbeat traders.

Getting into a math trade

Math trades occur fairly frequently, but at irregular intervals. Subscribe to the Math Trade Announcements Thread to be notified of new math trades. If you're impatient, it's also possible that a moderator could be convinced to run a new math trade if one hasn't occurred in a while.

  • For math trades using the OLWLG login to the OLWLG and check step 2 for lists of active math trades.

How does the trade algorithm work?

Early math trades consisted of only a couple dozen entries and were computed by hand. Modern math trades regularly include thousands of entries and are computed with tools such as TradeMaximizer that automatically determine the maximum number of trades possible. The wiki entry for TradeMaximizer includes an overview of the graph theory algorithm.

These older tools were used prior to the algorithm's discover and are now obsolete.

Tips for new traders

  • Follow the usual guidelines for trades and sales. Describe your game clearly. In particular, mention the condition of the game, if it is in a language other than English, and the edition (if you know). When sending the game, package it carefully.
  • It can pay to check other traders' want lists. Typically, math trades have an associated "request" geeklist. By offering a game lots of other people want, you greatly increase the chance you'll get something you want, too.
  • If you're really hoping to get a particular game or games, try to offer a game of roughly the same or higher trade value.
  • When offering multiple items together, try to group games that are related somehow. That way, you're more likely to find someone interested in the whole lot.
  • "Tipping" the moderator (giving them a GeekGold) at the end of a math trade is nice, especially if you got a trade, but not required. (The same applies to the OLWLG tool.)
  • If you used the trade manager, be sure to leave appropriate feedback after you receive your game. There is some debate about whether you should leave feedback to the person to whom you sent the game; the most common opinion is that you should generally leave positive feedback to the recipient unless there are serious problems with their communication.
  • For some additional useful ideas, take a look at starspangledgirl's post, here AFTER the Math Trade Guide .


If you have any questions about participating in math trades, please post in the BGG Trade Forums.


Misc. information

* Math Trade Tools BGG Guild
* European shipping costs
* Aussie Maths Trade
* No-Ship Math Trade suggestions for convention organizers

Video Help & Runthroughs

These very useful (but long) videos take you through the entire process very carefully with lots of tips. Recorded during August 2013 by Rahdo.

BGG Video Page:
(I don't know how to link nicely to a BGG video, someone who does please edit!)

YouTube direct links:
Part I (finding a trade and listing your games)

Part II: (building your want list with the OLWLG)

Part III: (shipping your games with the trade manager)

Part IV: (editorial & advanced tips)

Four older (2010) and shorter videos made by boathouselooper are here:

The narrator is not so enthusiastic but the videos are MUCH shorter!

Part 1. Finding Trades and adding items [4m19s]

Part 2: Adding items via the OnLine Want List Generator (OLWLG) [6m24s]

Part 3: Editing your want list in the OLWLG [2m59s]

Part 4: Duplicate Protection in the OLWLG [3m59s]

[What Links Here]