# Temperature tracking (BBT) when trying to conceive

> The tiny morning rise that confirms you ovulated.

Category: Fertility & TTC · 5 min read · Written by the Splash team · Sources checked October 2026
URL: https://splash.care/learn/fertility-ttc/bbt-for-ttc

## Quick answer

- BBT rises slightly after ovulation and stays up until your period.
- Measure before getting out of bed, same time daily, with a basal thermometer.
- It confirms ovulation after the fact – best used alongside mucus and LH tests.
- Temps staying high past your period date can hint at pregnancy.

Your [Basal body temperature](https://splash.care/learn/glossary/bbt) is your body’s resting temperature. After [ovulation](https://splash.care/learn/glossary/ovulation), the [hormone](https://splash.care/learn/cycle-basics/hormones-explained) [progesterone](https://splash.care/learn/glossary/progesterone) nudges it up a little and keeps it there until your [next period](https://splash.care/tools/period-calculator). Track it for a few cycles and you can see, pretty clearly, whether and roughly when you ovulated.

## How big is the rise?

Small! Cleveland Clinic says the shift is usually somewhere around 0.2–0.6°C (0.4–1°F). That’s why you need a basal thermometer that reads to two decimal places.

**3 days** Temps staying higher for 3 days in a row suggests ovulation has happened

## How to take it

1. Keep the thermometer by your bed.
2. Take your temperature as soon as you wake – before you get up, talk or drink anything.
3. Measure at about the same time every day, in the same place (usually your mouth).
4. [Log it](https://splash.care/learn/cycle-basics/tracking-101) in the app from day 1 of your period.
5. Keep going for at least three cycles to spot your pattern.

## Things that throw readings off

- [Alcohol](https://splash.care/learn/nutrition/caffeine-alcohol) the night before
- Poor or broken [sleep](https://splash.care/learn/movement-sleep/sleep-cycle)
- Illness or fever
- Stress
- Travel across time zones
- Some medicines
- Breastfeeding

> **Splash says:** had a wild night or a terrible sleep? Log it anyway and add a note. One odd dot won’t ruin your chart.

**Myth:** BBT tells you when to have sex this cycle.

**Fact:** The rise happens AFTER ovulation, when the fertile window is closing. Its superpower is showing your pattern so you can time things better next cycle.

- **Period:** Temps typically sit in your lower range.
- **Follicular:** Lower temps continue. Some people see a small dip just before the rise.
- **Ovulation:** Look for the shift: a sustained rise over a few days.
- **Luteal:** Temps stay higher. If they stay up past when your period is due, it may be time for a pregnancy test.

### When to see a doctor

If your chart never shows a clear rise over several cycles, or your second half (rise to period) is consistently very short, it’s worth discussing with a GP. A chart is a great thing to bring to that appointment.

## Sources

1. [Cleveland Clinic – Basal body temperature](https://my.clevelandclinic.org/health/articles/21065-basal-body-temperature)
2. [NHS – Natural family planning (fertility awareness)](https://www.nhs.uk/contraception/methods-of-contraception/natural-family-planning/)
3. [Cleveland Clinic – Ovulation](https://my.clevelandclinic.org/health/articles/23439-ovulation)

This is general information, not medical advice. Splash can’t diagnose. If you’re worried, talk to a GP, pharmacist or sexual health clinic. In an emergency call 999 (UK) or 911 (US).