Fever Check Calculator
Fever or not plus next steps from temp and age group.
What it does
Fever numbers need age context. The same 101.5 F worries nobody in an adult, watches a child, and alarms an infant under three months.
The tool above compares temperature to age bands. An adult at 101.5 F reads Fever with rest and fluids, below the 103 high line. The metric match is 38.6 C against the 38 line.
One hundred point four marks fever for all ages. High lines then split: 104 for kids, 103 for adults, with infants skipping straight to call now.
Care stays simple. Fluids, rest, and rechecks carry most fevers, while breathing trouble, stiff necks, and dehydration override any number.
Thermometers vary. Mouth, ear, and forehead read differently through the day, so repeat a surprising number before acting.
How to use
- Pick imperial (F) or metric (C).
- Pick age group.
- Enter temperature: 101.5 F or 38.6 C suits the default.
- Read status first.
- Read fever line next.
- Read action and follow red flags.
Formula
- age
- Infant, child, or adult bands.
- temp
- Body temperature.
Infants under 3 months skip bands: any fever means call now. Numbers guide, symptoms decide urgency.
Worked example
Example: adult, 101.5 F
Imperial defaults: adult at 101.5 F. These are also the default values, so the page opens on this answer.
- Adult with 101.5 F.
- Line: 100.4 F marks fever.
- 101.5 beats 100.4, below 103 high line.
- Status: Fever.
- Tool shows Fever, 100.4 F fever line, Rest and fluids.
Reference table
| Group | Fever at | High at |
|---|---|---|
| Infant | 100.4 F | Call now |
| Child | 100.4 F | 104 F |
| Adult | 100.4 F | 103 F |
| Metric | 38 C | 40 C child |
Limits
- Screening guide only, not medical advice.
- Symptoms override numbers.
- Thermometers vary by type.
- Infants need lowest thresholds.
Common mistakes
- One reading, instant panic.
- Adult lines applied to infants.
- Ignoring breathing and rash flags.
- Dosing without weight checks.
- Skipping rechecks after medicine.
Try it yourself
Quick checks. Answers sit tucked under each question.
Child at 99 F?
99 F sits below 100.4, so No fever with usual care.
Adult at 39 C metric?
39 C is 102.2 F, above 100.4, so Fever. Adult action is rest and fluids.
Questions
Fever at 101.5 F adult?
Compare against 100.4 F (38 C). Here 101.5 beats it, so Fever with rest and fluids.
Infant with fever?
Any fever under 3 months means call now. Tiny babies hide illness well.
High fever lines?
At 104 F (40 C) for kids or 103 F (39.4 C) for adults, call the same day.
Fever care basics?
Rest, fluids, and rechecks. Fever itself fights germs; comfort and hydration rule.
Retake temperature?
Yes. Thermometer type and timing shift readings, so repeat before acting.
Red flags beyond numbers?
No. Breathing trouble, stiff neck, rashes, and dehydration need urgent care whatever the number.