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Armband Size Guide

Upper arm circumference

How to Measure

  1. 1Wrap a flexible tape measure around your upper arm
  2. 2Measure at the fullest part (mid-bicep)
  3. 3Note in inches or centimeters

Size chart

Size Inches cm
Standard Armband 8.5″ – 15.5″ 21.5 – 39 cm
Extra-Long Armband 12.5″ – 18.5″ 31.5 – 47 cm
Both armbands fit most body types.
Additional bra extenders can be purchased at any store if larger sizing is required.

Track your cycle while you sleep.

Get lab-grade cycle insights without the 6 a.m. alarm. Tempdrop tracks your basal body temperature while you sleep. No guesswork, no strict wake-up rules - just clear, reliable data that helps you identify your peak fertile days and verify exactly when you've ovulated.

Why Temperature Matters

The science ofovulation tracking.

After ovulation, the natural hormone, progesterone, causes your basal body temperature to rise and remain elevated throughout your luteal phase, until you get your period. By tracking this distinctive thermal shift, Tempdrop enables you to confidently confirm ovulation and accurately map the phases of your cycle.

The Tempdrop Method

From overnight data tocycle certainty.

Tempdrop automates the collection of your basal body temperature (BBT) by continuously tracking while you rest. Our patented technology isolates your true resting temperature from everyday sleep disruptions and environmental variables, transforming your data into verified cycle insights.

Step #1

Wear overnight

Slide Tempdrop onto your upper arm, over the axillary artery, before you sleep. The medical-grade sensor monitors your temperature continuously while you rest, eliminating the need for a rigid, waking routine.

Wear overnight
Step #2

Collect continuous data

Instead of capturing a single, manual reading, the Tempdrop sensor records thousands of data points throughout the night. This continuous monitoring ensures your baseline resting temperature is captured at its lowest physiological point.

Collect continuous data
Step #3

Filter real-life disturbances

Tempdrop's patented algorithm automatically filters out external variables - such as restless movement, waking for babies or children, or poor sleep quality - to pinpoint your true resting temperature with absolute accuracy.

Filter real-life disturbances
Step #4

Sync for instant verification

Sync the sensor to the app at a time convenient to you. The Tempdrop sensor instantly maps your temperature data to your fertility chart to confirm ovulation, track your symptoms, and accurately anticipate your next period or the best time to test for pregnancy.

Sync for instant verification

The Data Science Behind the Sensor

How our smart sensor isolates your true resting temperature.

Real life means broken sleep and unpredictable schedules—which easily ruin standard BBT charts. Tempdrop solves this by taking continuous basal body temperature readings while you sleep. A proprietary fertility tracking algorithm then removes disruptions such as wakings and physical movements, leaving you with an accurate, true resting temperature.

The goal

Our goal is to turn precise daily data into a clear cycle pattern. By focusing on your overall trend, Tempdrop accurately pinpoints your ovulation window.

Clinical Evidence

Backed by published research.

A peer-reviewed study evaluated Tempdrop's overnight axillary temperature sensor against LH ovulation testing as a reference method.

Peer-reviewed study

Study snapshot

Compared with LH ovulation testing as a reference method

Compared with LH ovulation testing as a reference method

Illustrative example of a study participant’s data. Not individual result.

98.6%

Accuracy for fertile-day classification

194

Cycles analyzed

125

Participants

Read the Research

Sensor + app

The sensor collects overnight. The app maps your fertility.

The Tempdrop sensor tracks your basal body temperature (BBT) while you sleep. The Tempdrop app helps you visualize your fertility data. With a quick sync, it automatically builds your fertility chart, enables you to add your symptoms, and pinpoints your ovulation day at a glance.

Shop Tempdrop

An Introduction to Tempdrop

From setup to your first cycle insights in the app.

Watch on YouTube · 3 min
An Introduction to Tempdrop

An Introduction to Tempdrop

From setup to your first cycle insights in the app.

Watch on YouTube · 3 min
Sync whenever convenient
Shop Tempdrop

Free app included

Free fertility tracking app. Deepercycle insights with Premium.

Free fertility tracking app. Deeper cycle insightswith Premium.

Every Tempdrop works with the free app, so you can sync and start tracking right away. Premium adds automatic interpretation and deeper insights when you are ready.

Every Tempdrop sensor pairs with our free app, giving you the tools to track your BBT, log fertility symptoms, and sync your overnight readings to your favorite third-party app. Premium is optional and includes a free trial, offering deeper cycle insights and automatic interpretations for those who want extra guidance.

Get the app

Available on iOS and Android

Download on the App StoreGet it on Google Play
Everything you need

Free

Tempdrop brings the full fertility tracking solution to your smartphone.


Guided setup and onboarding

Daily temperature readings

Temperature trend chart

Period and symptom logging

Wear and sync reminders

Calendar view

Apple Health and Google Health integration

Learn More
Most popular plan

Premium

Unlock deeper insights with advanced cycle analysis, sleep quality data, and expert fertility education.


All Free features +

Ovulation prediction and confirmation

Fertile window cycle forecasts

Sleep quality and sleep phases

Enhanced calendar view

Cycle-phase tailored content

Exclusive fertility awareness education

Learn More

Get the app

Available on iOS and Android

Download on the App StoreGet it on Google Play

Less Morning Pressure

No strict wake-up routine required.

No strict wake-uproutine required.

Forget the strict rules of traditional basal body temperature tracking. Tempdrop tracks your BBT automatically while you sleep, allowing you to sync and view your data whenever it suits your schedule.

Shop Tempdrop

manual tracking

  • Rigid wake-up routine
  • Must measure before moving or talking
  • Easily missed on busy mornings
  • Disrupted by interrupted sleep

tempdrop

  • Continuous overnight tracking
  • Sync at your convenience (no daily rush)
  • Unaffected by variable sleep schedules
  • Automated BBT charting
  • Built for variable sleep schedules
Shop Tempdrop

Buy with Confidence

Everything you need toget started.

Backed by an included manufacturer warranty, premium customer support, and global regulatory standards for ultimate peace of mind.

  • Flexible data syncing

    No time pressure - sync your readings whenever it suits your day.

  • Adapts to irregular cycles

    Engineered to provide accurate, reliable tracking for varied sleep and cycle patterns.

  • Smart filtering

    Active Temperature-Noise Cancellation and learning algorithms.

  • Flexible data syncing

    No time pressure - sync your readings whenever it suits your day.

  • Adapts to irregular cycles

    Engineered to provide accurate, reliable tracking for varied sleep and cycle patterns.

  • Smart filtering

    Active Temperature-Noise Cancellation and learning algorithms.

  • Full data access

    Download, export, and share your data any time.

  • Universal app compatibility

    Integrates seamlessly with your favorite health and fertility charting platforms.

  • Dedicated customer care

    Get real human support alongside your included manufacturer warranty.

  • Full data access

    Download, export, and share your data any time.

  • Universal app compatibility

    Integrates seamlessly with your favorite health and fertility charting platforms.

  • Dedicated customer care

    Get real human support alongside your included manufacturer warranty.

  • FDA Registered

    Registered for safety and quality with the U.S. Food & Drug Administration.

  • CE Mark

    Meets strict European safety, health, and environmental regulatory standards.

  • HSA / FSA Eligible

    Covered under most health savings accounts.

  • FDA Registered

    Registered for safety and quality with the U.S. Food & Drug Administration.

  • CE Mark

    Meets strict European safety, health, and environmental regulatory standards.

  • HSA / FSA Eligible

    Covered under most health savings accounts.

FAQ

Your top questions,answered.

What is Tempdrop?

Tempdrop is a wearable fertility monitor that measures your basal body temperature (BBT) while you sleep - no alarm, no schedule, no invalid readings. Along with its fertility tracking app, Tempdrop automates the data collection required for accurate cycle tracking, providing the confidence you need to manage your reproductive health without the stress of manual temping.