Ironically you can analyse wasted votes by including all surplus votes fro wining candidates e.g. if a candidates wins with a majority of 30,000, in theory, 29,999 of those votes were not needed and did not in effect the result.
Furthermore FPTP elects too many constituency MP's they are elected by a minority of the electorate. E.g. Annabelle Ewing was elected with only 29.9% of the votes obviously this goes against meaning of democracy where the precept is majority rules. It could be said that she has no mandate as a representative, as 69.9% of the electorate where against her in the election.
A popular criticism of FPTP is that it creates minority governments. In the 2001 election Labour won 44% of the vote so in effect 56% of the country did not vote for a Labour government. However in a multi party system it is unrealistic to expect a party to win 50% of the popular vote.
FPTP makes some votes more valuable than others as 75% of votes are known as "safe seats" which means that they do not change hands between elections. Therefore 25% of seats are marginal and that it is the "floating voters" in these marginal seats that will determine the outcome and the results of an election e.g. Springburn has a Labour "safe seat" and Ayr has a marginal seat. As in 2001, the Ayr seat switched from SNP to Conservatives. Therefore, many votes are wasted in areas with safe seats, as they do not go towards the election of any candidate. Safe seats can also make people not vote, as they do not see the point in voting as they feel that the party they want to win will e.g. only 45% of voters in Shettleston voted as a result of "safe seats". This problem has been put forward as the reason why voter turnout is falling. In the 2001 elections the average turnout in 100 seats with the smallest majorities was 63.6 but in the 100 seats with the largest majorities the turnout 53.9%. The other problem with the marginal seats where the result is in doubt literally every vote counts.