Consecutive vs Simultaneous Interpreting: What's the Difference?

Event organisers, HR teams and managers who book interpreters for the first time usually face the same question: should the interpreter speak after the speaker or at the same time? The answer changes the length of your agenda, the equipment you hire, the number of interpreters you book and the cost.

This guide explains how consecutive and simultaneous interpreting work, what each needs in practice, and how to choose between them. For an overview of every interpreting format, including remote and liaison interpreting, see our guide to types of interpreting and how to choose the right service.

What is consecutive interpreting?

Consecutive interpreting is a mode in which the speaker talks for a short passage, pauses, and the interpreter then renders that passage into the other language. The interpreter usually takes notes using a personal shorthand system, so they can reproduce a passage of several sentences accurately.

Consecutive interpreting works in both directions, which makes it the natural mode for conversations: negotiations, interviews, site visits, medical consultations and HR meetings. It needs no booths or headsets. The trade-off is time, because every passage is heard twice. NHS England's guidance for commissioners on interpreting in primary care notes that when an interpreter is needed, a consultation needs extra time, "typically double that of a regular appointment".

What is simultaneous interpreting?

Simultaneous interpreting is a mode in which the interpreter listens and speaks at the same time, staying a few words behind the speaker. Listeners hear the interpretation through headsets, so the event runs at its normal pace.

Because simultaneous interpreting demands intense concentration, interpreters work in teams and take turns. The professional standards published by the Italian region of the International Association of Conference Interpreters (AIIC) state: "As a general rule, a team is composed of at least two interpreters per language and per booth." The same AIIC Italia professional standards also say members should not, as a general rule, interpret simultaneously in a booth "either alone or without the availability of a colleague to relieve them should the need arise".

Whispered interpreting (chuchotage)

Whispered interpreting, or chuchotage, is simultaneous interpreting delivered quietly to one or two listeners sitting next to the interpreter, without a booth. It suits a board meeting where one delegate does not speak the working language. It is tiring for the interpreter and can distract others in a small room, so it only works for short sessions and very small groups. AIIC Italia's standards still call for at least two interpreters for whispered assignments.

Consecutive vs simultaneous interpreting: side-by-side comparison

The table below compares the two modes on the points that usually decide a booking.

What equipment does simultaneous interpreting need?

Simultaneous interpreting on site needs soundproof booths with a view of the room, interpreter consoles, a feed from every microphone in the room, and receivers with headsets for the audience. ISO publishes standards that venues and equipment suppliers use to specify this set-up:

• ISO 17651-1:2024 covers permanent booths and replaced ISO 2603:2016.
• ISO 17651-2:2024 covers mobile booths, which ISO describes as booths that "can be dismantled, moved and set up in a room". It replaced ISO 4043:2016, which ISO now lists as withdrawn.
• ISO 20109:2016 "specifies requirements for equipment used for simultaneous interpreting", according to the ISO catalogue entry for ISO 20109.
• ISO 20108:2017 sets requirements for the quality and transmission of sound and image input to interpreters.

The ISO 17651-2 abstract states that the booth standard "is to be used in conjunction with ISO 20109". In practice, ask your venue or audio-visual supplier to confirm that booths and consoles meet these standards before you sign a contract. When interpreters work from a hub or from home instead, the platform falls under ISO 24019, covered in our guide to setting up remote interpreting by video and phone.

How many interpreters do you need for each mode?

The number of interpreters depends on the mode, the number of languages and the length of the day. AIIC Italia's team strength rules set these minimums:

• Consecutive, two languages: two interpreters, which may be reduced to one "under exceptional circumstances" where quality and health are fully considered.
• Simultaneous: at least two interpreters per booth, normally one booth per target language, and at least three interpreters in a two-way booth that provides relay.
• Working day: no more than "two sessions of between two-and-a-half and three hours each".

Short business meetings in consecutive mode are often covered by one interpreter, which is why consecutive is usually the cheaper option for small events. A full-day conference in three languages, by contrast, may need several booths and a larger team. Our article on how much an interpreter costs in the UK explains how team size drives the budget.

Which mode should you choose for your event?

Choose consecutive interpreting for small, interactive settings and simultaneous interpreting for larger audiences or long programmes. Work through these questions in order:

1. How many people need interpreting? One to three listeners suits consecutive or whispered interpreting; a large room usually justifies simultaneous equipment.
2. Is the event a dialogue or a presentation? Dialogue favours consecutive; one-to-many presentations favour simultaneous.
3. Can the agenda absorb extra time? If not, consecutive interpreting will force you to cut content.
4. How many languages are involved? More than two languages almost always points to simultaneous interpreting with several booths.
5. Does the venue have booths, or space for mobile booths? If not, consider remote simultaneous interpreting or a portable tour-guide system for small groups.
6. Is precision on every sentence critical? Consecutive gives participants time to check understanding, which is why it remains common in sensitive settings such as interpreted HR investigations and disciplinary hearings.

Common mistakes when choosing between consecutive and simultaneous interpreting

• Booking consecutive interpreting for a packed agenda. A two-hour programme with consecutive interpreting can need close to four hours. Plan the timetable around the mode, not the other way round.
• Booking one simultaneous interpreter for a full day. Professional standards expect a colleague in the booth. A single interpreter working alone for hours puts accuracy at risk.
• Using whispered interpreting for a whole conference. Chuchotage is meant for short sessions and one or two listeners; beyond that, hire equipment.
• Forgetting the audio feed. Simultaneous interpreters can only interpret what they hear clearly. Every speaker, including audience questions, needs a microphone connected to the interpreting system.
• Leaving preparation to the day. Both modes depend on preparation. Send slides, speeches and glossaries in advance, as explained in how to brief an interpreter.

How TranslationWorks can help

TranslationWorks is a UK-based language services agency that provides professional interpreting alongside translation, transcreation and transcription, working with native-speaking linguists across more than 150 languages. If you are unsure whether your meeting or event needs consecutive or simultaneous interpreting, describe the format, audience size, languages and venue, and we will recommend a suitable approach. Our interpreting services page sets out the formats and settings we cover. TranslationWorks is ISO 17100 certified, ISO 9001 and ISO 27001 registered and Cyber Essentials certified, which matters when meeting content is confidential. To plan your event, request a free interpreting quote, which we provide within 24 hours.