The “Avg. delay” is the average speed to answer of all calls (ASA). The number of seconds input in the “Call answering target” is the your target for answering calls but you specify that only a certain percentage will meet this target.
Average delay is calculated by determining Workload(Calls per Interval*AHT per Interval/1800 or 3600 (depending on halh-hour or hour staffing targets) and target online agents, Based on the arrival times and true position staff a percentage of calls may not be answered immediately. The percentage of calls delayed(delayed calls/Total calls) * the avg delay = the average delay of all calls. Your target ASA on the calculator is based on the same principal. Actually, Avg delay is a incorrect term because a percentage of calls do not receive any delay, therefore average speed of answer may be a better term.