The answer is almost never one. Simultaneous interpreting is among the most cognitively demanding professional tasks there is, and the staffing rules that follow from that are the single biggest driver of what a conference costs.
The rule: two per booth, three past one day
AIIC treats a minimum of two interpreters per language booth as a professional standard rather than a preference, for any session requiring simultaneous interpretation longer than about an hour. Interpreters rotate every 20 to 30 minutes because sustained output degrades sharply after that. For multi-day events the guidance rises to three per booth, so the team can hold quality across consecutive days rather than arriving at day three exhausted.
Booths scale with languages, not with audience
One booth per language pair. A three-language event running English, Arabic and French needs two booths, not three, because English is the floor. Add a fourth language and you add a booth and its whole team, which is why cost steps rather than climbing smoothly.
| Event | Booths | Interpreters |
|---|---|---|
| One day, EN plus ES | 1 | 2 |
| Two days, EN plus ES and FR | 2 | 6 |
| Three days, EN plus ES, FR, AR, ZH | 4 | 12 |
| Two days, AR floor with EN and FR via pivot | 2 plus relay | 6 |
Concurrent sessions multiply everything
A six-track conference does not need six interpreters. It needs a full team per language per track running at the same time. This is where budgets break without warning, because the agenda looks like one event while the staffing is effectively six.
The most common costing error is quoting a multi-day event at two interpreters per booth. On a three-day conference with four booths that is 8 interpreters quoted against 12 required - a third of the labour cost missing before anything else is added.
What sits on top of the team
Once you have the headcount, the rest follows: a booth per language, receivers scaled to delegates rather than languages, a technician, and travel and per diem for anyone not local. On multi-booth events a chief interpreter coordinates handoffs between teams and is billed separately.
Price this in about a minute
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