For academic accounts, the cost of using Pro Features is 2 cents + 5% of worker compensation per completion; for business accounts, the fee is 5 cents + 6% of worker compensation. Pro Feature fees must be rounded to the nearest penny and charged by the completion (i.e., as workers complete and are approved for each HIT). Because fees are calculated per completion, rounding up to the nearest penny for each worker sometimes causes the actual cost of a study to be higher than what researchers estimate. We charge fees as each worker is approved because researcher's sometimes stop a study before reaching the total number of requested participants.
NOTE: When calculating fees for using Pro Features, all values less than a penny are rounded up to the nearest penny regardless of whether the partial value is greater than or less than 5.
Let's assume you have an academic account. If you were paying workers 50 cents, the TurkPrime fee would be 2 cents per worker plus 5% of the 50 cents you are compensating each worker (5% * $0.50) = $.025. However, because TurkPrime cannot charge for fractions of a penny, the calculation would get rounded up to, $.03 cents per worker. If you collected 100 responses, the total Pro Feature cost would therefore be ($0.02 * 100 workers) + ($0.03 * 100 workers) = $5.00. However, if you were to calculate the formula before rounding, you might assume the total charge is $4.50 [($0.02 * 100 workers) + ($0.025 * 100 workers).