basic ethereum zepplin crowdsale smart contract token rate question

Question

A basic question on how zepplin solidity code calculates token rates. The code comments say

// how many token units a buyer gets per wei

 uint256 public rate;

however we cannot get it to serve back 1000 tokens per ETH when we pass an ammount as the rate into;

function Crowdsale(uint256 _startTime, uint256 _endTime, uint256 _rate, address _wallet) {
    require(_startTime >= now);
    require(_endTime >= _startTime);
    require(_rate > 0);
    require(_wallet != address(0));

    token = createTokenContract();
    startTime = _startTime;
    endTime = _endTime;
    rate = _rate;
    wallet = _wallet;
  }

the rate is used in;

   uint256 weiAmount = msg.value;

    // calculate token amount to be created
    uint256 tokens = weiAmount.mul(rate);

Again, whatever rate we send in, high or low does not come out at 1,000 tokens per eth.

can anyone explain the working of this calculation so we can get there?

Thanks

Answer 1

This is likely due to your decimals value. I'm assuming you have the tokens decimals set to 18? Notice that instead of 1000 tokens, you're getting 1,000,000,000,000,000,000, where 18 of those 0s are from your decimals variable and the other 3 are the 1000. This is all expected behavior.