Comparison

Tempdrop vs Chart35

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Tempdrop

This app works with a specialized thermometer to track subtle overnight temperature changes. It helps identify hormonal fluctuations throughout the menstrual cycle, pinpoint ovulation, and predict cycle phases. The data supports fertility awareness and cycle tracking.

Highlights
  • Basal body temperature tracking
  • Ovulation pinpointing
  • Menstrual cycle prediction
  • Hormonal fluctuation correlation
  • Fertility awareness support
Features
Read full description

The Tempdrop app is designed to complement the Tempdrop device - a personalized user-specific thermometer that captures minute temperature variations throughout the night to pinpoint the basal body temperature. Detected variations in temperature correlate with hormonal fluctuations throughout the menstrual cycle. When used with the Tempdrop device, this app can help users to pinpoint ovulation and effectively track and predict the varying phases of the cycle. Disclaimer: The Tempdrop sensor and app are intended as complementary instruments to enhance your ability to monitor your fertility and share health details. The app and its wearable sensor, in themselves, are not, nor are they intended to be, a fertility monitor, a substitute for contraception, or a birth control method. We recognize the need of some to use the data and information provided to support ongoing health and menstrual cycle tracking, however, it is important to note that this should NOT be used as a substitute for an in-presence qualified professional, medical analysis, advice, guidance, or treatment. We strongly advise seeking a qualified Fertility Awareness instructor or other self-teaching resources to learn a symptothermal method and support your fertility journey. The provided interpretations and prediction guidelines are not suitable for use with irregular cycles. Optimal performance is dependent on correct and consistent use. Individual usage, wearing, input, and circumstances can affect the data. The user is fully responsible for the individual data inputs. The Tempdrop Sensor is approved for use in the USA, and is registered in the FDA database under registration number 3016099071. The device is classified as "Device, Fertility Diagnostic, Proceptive”. A link to the terms of use - https://www.tempdrop.com/pages/tos A link to the privacy policy - https://www.tempdrop.com/pages/privacy-policy

About

Chart35

Features
Read full description

Chart35 is a private fertility-charting app for the Creighton Model FertilityCare System (CrMS). Record each day's observation, see your color-coded stamp and chart, and keep your record on your own device. YOUR DATA STAYS WITH YOU Chart35 is offline-first. Your observations live on your device and the app works with no connection. Account sync is optional. When you turn it on, your records are encrypted on your device before they are uploaded, so the server stores data it cannot read. CHART THE WAY YOU WERE TAUGHT - Color-coded stamps: red, green, white, and yellow, matching standard CrMS charting. - Observation codes for bleeding, mucus, and frequency, built from the codes you already use. - Peak Day and post-peak count tracking. - Chart and calendar views, with Normal, Compact, and Trend zoom to see one cycle or many at a glance. - Insights: cycle count, average cycle length, and a cycle-length trend at a glance. SHARE WITH YOUR PRACTITIONER Generate a read-only link to your chart for your FertilityCare Practitioner. The link is encrypted so the server cannot read the shared data, and you can revoke it at any time. BUILT FOR REVIEW Your notes stay private and are never included in a shared chart. You decide what syncs and what is shared. You can delete your account and data at any time. ABOUT THE METHOD Chart35 is a charting and record-keeping tool. It is not medical advice and does not interpret your fertility for you. The Creighton Model is learned with a certified FertilityCare Practitioner. Yellow-stamp (Base Infertile Pattern) use in particular should only follow a baseline established with your practitioner. To find a practitioner, see your instructor or a FertilityCare center. Chart35 is independent and is not affiliated with or endorsed by the Saint Paul VI Institute or the creators of the Creighton Model System. "Creighton Model" and "FertilityCare" refer to the method and are used to describe what the app charts.

Screenshots

Tempdrop4 screens
Chart354 screens

Verdict

The call

The clearest difference is in-app purchases: Chart35 at none against Tempdrop's 6. Chart35 also leads on update cadence (every 6 days vs every 3 months). On price, ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Tempdrop sells 6 in-app purchases, starting at $2.99 per month. Chart35 asks for nothing beyond the download.

UpkeepUpdate frequency

Tempdrop ships an update every 3 months, Chart35 every 6 days. The most recent releases landed on October 13, 2026 and October 6, 2026 respectively.

Scorecard2 real differences · 8 level
Tempdrop versus Chart35: the parameters behind the verdict, then further details
ParameterTempdropChart35
PriceFreeFree
Rating4.2 (710 ratings) — better—
Positive reviews38.3% of reviews—
Number of ratings710 — better—
Update frequencyEvery 3 monthsEvery 6 days — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod, Apple Watch — better
Requires iOS15.015.0
Further details — not scored
Size103 MB5 MB
Age rating17+4+
DeveloperTempdrop IncStephens Page LLC

Bugs and requests

Tempdrop

Reported bugs

4 issues
  • App crashes and freezes
  • Issues with syncing device data
  • Inaccurate cycle predictions and phase tracking
  • Temperature data changes over time

Requested features

5 requests
  • Improved sleep tracking capabilities
  • More customizable symptom and data tracking
  • Ability to manually confirm ovulation
  • Integration with other fertility/health apps
  • Support for irregular cycles and postpartum/breastfeeding phases

Chart35

Not enough reviews yet to summarise bugs or requests.

In-app purchases

6 purchases

Tempdrop

Subscriptions6
  • Tempdrop Promo Premium monthly2 Months trial$2.991 Month
  • Tempdrop Premium monthly2 Months trial$6.001 Month
  • Tempdrop Promo Premium quarterly2 Months trial$7.993 Months
Show 3 more
  • Tempdrop Premium quarterly2 Months trial$15.003 Months
  • Tempdrop Promo Premium yearly2 Months trial$24.991 Year
  • Tempdrop Premium yearly*2 Months trial$48.001 Year
None

Chart35

No in-app purchases

Questions

Is Tempdrop free?
Tempdrop is free to download, with in-app purchases available.
Is Chart35 free?
Chart35 is free to download, with no in-app purchases.
Do Tempdrop or Chart35 have ads?
Neither Tempdrop nor Chart35 shows ads.
Which is updated more often, Tempdrop or Chart35?
Tempdrop ships an update every 3 months, and Chart35 every 6 days. Most recently, Tempdrop was updated on October 13, 2026 and Chart35 on October 6, 2026.

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