There are 73 constituency seats and 56 regional seats in the Scottish voting system. Combined, these return 129 Members to the Scottish Parliament(MSPs).
Each elector(voter) has two votes.
The first vote is used to select a candidate who is standing in a constituency. This relies on the First Past The Post (FPTP) system where the candidate with the highest number of votes will become elected as the MSP for that constituency. The Political Party represented by the winning candidate adds to the number of seats won by that party.
The second vote is used to select a party as opposed to an individual candidate and is known as the Additional Member System (AMS). Eight regions (comprising of 8 to 10 constituencies) have a list of 7 parliamentary seats allocated to them. Which party wins which seat is determined by votes cast and processed through the D'Hondt system - a mathematical process to score the votes over a number of rounds. In each round, the highest scoring party is allocated a seat. There are 7 seats available, so the process lasts for 7 rounds.
Here is a demonstration of how the D'Hondt method works for the Scottish Parliamentary Elections.
Lets assume we are looking at a region with 9 constituencies and we will allocate votes according to the general polls at the time of writing which suggests 50% support for the SNP. In the constituency seats, the SNP did well and gained all 9 seats in the region. No other party gained a seat as the FPTP system only recognises the candidate with the highest vote count in each case.
Sticking with the 50% poll, in the regional elections, the SNP received 52,000 votes, Labour receive 24,500 Conservative 15,500 Libdems 3,000, Greens 4,000 and all other parties received a combined vote of just 2,000.
These values are inserted in the table below
| Party |  |
 |
 |
 |
 |
 |
|---|---|---|---|---|---|---|
| Regional votes | ||||||
| FPTP seats |
Round 1
To calculate which party gains the first list seat, the Regional votes are divided by the constituency seats (FPTP seats) and the highest score wins the seat. (Note, before the first calculations are made, every party has their constituency seat count increased by 1 to avoid mathematical problems caused by dividing a number by zero - i.e. you can't). We will refer to the seat count as the 'divisor'.
| Round 1 | ||||||
|---|---|---|---|---|---|---|
| Labour Seat |
Round 2
Labour won the first regional (list) seat (so their divisor goes up by 1). To find out who wins the second seat, the calculations are done again. Labour's score is effectively halved and the Tory score is the highest.
| Round 2 | ||||||
|---|---|---|---|---|---|---|
| Tory Seat |
Round 3
The Tory divisor is increased by 1 because of their round 2 victory. The calculations are done for the third seat and Labour has the highest score and win another seat.
| Round 3 | ||||||
|---|---|---|---|---|---|---|
| Labour Seat |
Round 4
The Labour divisor is increased by 1 because of their round 3 victory. The calculations are done for the fourth seat and Labour, once again, have the highest count. Labour wins the seat.
| Round 4 | ||||||
|---|---|---|---|---|---|---|
| Labour Seat |
Round 5
The Labour divisor is increased by 1 because of their round 4 victory. The calculations are done for the fifth seat. The Tories have the highest score and win the seat.
| Round 5 | ||||||
|---|---|---|---|---|---|---|
| Tory Seat |
Round 6
The Tory divisor is increased by 1 because of their round 5 victory. The calculations are done for the sixth seat and Labour have the highest score, winning the seat.
| Round 6 | ||||||
|---|---|---|---|---|---|---|
| Labour Seat |
Round 7
This is the seventh (and final round). The Labour divisor is increased by 1 because of their round 6 victory. The calculations are done and the SNP claim the last seat.
| Round 7 | ||||||
|---|---|---|---|---|---|---|
| SNP Seat |
The results
From the results shown, we can see that the high number of votes for the SNP didn't return the most regional seats. In fact, Labour gained 4 seats - yet they had half the votes of the SNP. The Tories also did well with 2 seats awarded for the rather low number of votes cast for them. The crucial factor at play is the number of constituency seats won in the region. In this example, the SNP won all the constituency seats, so this had a big impact on their ability to secure regional (list) seats - despite having over 50% of the regional vote. This is exactly how the system is designed to work as it introduces a balancing mechanism over the two elections to provide a result that reflects a more proportional representation of the votes cast.
| Seats gained |
|---|
Fun with Numbers
The calculator (below) allows you to input a variety of voting results and it will return the number of List Seats.
To use the calculator, supply the number of Regional Votes for each party.
Input the number of FPTP Seats they won for the region in question. Enter a zero (or just leave the box blank) for Parties who did not gain any Constituency Seats.
All Scottish Regional areas have 7 list seats, so you can leave the number of seats at the default value of 7.
Press the 
button to start the scoring process. The number of seats gained will be shown and which round of scoring generated the seats for any given party (highlighted in the colour of that party). You can experiment with different values to see how the outcome will change - just input new values and press the button again.
Tactical Voting
There are many sources that claim the second vote (especially from SNP voters) should be used 'wisely' to help other pro-independence parties gain list seats and hence gain a voice in the Scottish Government. This would also deny Unionist parties list seats into the bargain.
This is a complete and utter MYTH.
For this idea to have a remote chance of working, it would require a substantial transfer of regional votes - but this would be greatly reduced in effectiveness since there are a number of pro-independence parties standing and the votes would split amongst them.
In addition, any such scheme would seriously compromise the chance of the SNP securing a majority government and to be blunt, an SNP majority is in the best interests of every pro-independence party and the Yes movement in general. A reduced count for the SNP would ultimately favour the Unionist parties and more Labour and Tory list seats would emerge.
Referring back to the fairly 'real world' example of voting intention (used previously to show how the D'hondt system works) the second vote for the SNP is absolutely crucial in securing those all-important list seats. They need every seat they can get to break the barrier to a majority government and, if you have understood the way the D'hondt system works, it should be obvious that the greater the number of votes cast in the regional elections, the better the chance of securing one or more list seats.
Remember, there is a good chance the SNP will do well in the constituency seats. This will negatively impact their ability to get list seats (take another look at the example of how this works if its not yet clear).
Those who insist Tactical Voting can specifically influence the outcome of the seat allocation have misunderstood how the scoring system works (or they have a hidden agenda).
Play around with the calculator - and in a short time, you will be able to input values that will satisfy the claims made by these people. However, it should become obvious that for those circumstances to come true, you would need to be able to guarantee the various permutations of seats and votes in both FPTP and list seat elections for any given region.
This is impossible.
The purpose of this site is to offer free, reliable information and it is not in our gift to force anyone to vote one way or the other. We can only advise that everyone votes for the candidate/party of their choice and is fully aware that TACTICAL VOTING DOES NOT WORK IN THIS SYSTEM - and in the case of the SNP, there is a real risk of compromising the ability of the party to get a majority in Holyrood.
If that should happen, there will be no majority government and consequently, no chance of a referendum within the next term.
If that scenario is bad, it could also be compounded with unforeseen outcomes due to a failed attempt to implement tactical voting. Play around with the calculator and discover how subtle changes in votes can produce huge gains for the Unionist parties.
The bottom line: Vote for who you want based on sound thinking - don't be suckered into wasting your vote(s) on attempts to influence a robust system that was designed to prevent tactical voting (which it does very well).
