What is the normal oral body temperature range for most adults?

• A. 99.0°F to 100.5°F (37.2°C to 38.0°C)
• B. 96.5°F to 98.0°F
• C. 97.0°F to 98.5°F
• D. 97.8°F to 99.1°F (36.5°C to 37.3°C)

Answer: (D)

Normal oral temperature in adults isn’t a single fixed number but a range. Most adults read within about 97.8°F to 99.1°F (36.5°C to 37.3°C) when measured orally. This spread accounts for natural variation among people and small fluctuations from the time of day, recent activity, or what was eaten or drank just before the reading. In practice, 98.6°F is the classic average, but readings can comfortably fall within that 97.8–99.1°F window and still be considered normal. Measurements can be affected by factors like having eaten, drunk hot or cold fluids, or smoking shortly before taking the temperature, so for accuracy it’s best to wait a little after these activities and ensure the thermometer is placed properly under the tongue with lips closed.