The exchange rate from GBP to USD is determined around the 15th of the month following the donation. The exchange rate from USD back to GBP (for UK-based organizations) is determined around the 25th of the month. The exchange rate from GBP to USD is based on the mid-market rate and GlobalGiving picks up all conversion costs. The exchange rate at disbursement (USD to GBP for UK-based organizations) is based on our processor's rate which is typically 2% different than the mid-market rate at the time of disbursement.