Perfect OB Wheel vs ObCalc
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Perfect OB Wheel
This app is a comprehensive obstetrics calculator that provides detailed pregnancy information. It offers flexible input options and displays thorough results including estimated due dates, gestational ages, and fetal growth estimates.
- Flexible input (LMP, conception, EDC, ultrasound)
- Fast data entry options
- Detailed pregnancy results
- Accurate date calculations
- Persistence of last used data
- Optional pregnancy tracking upgrade
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Simple, fast, yet more thorough than any other pregnancy wheel available for the iPhone, Perfect OB Wheel is better than just a replacement for your trusty paper wheel. Here's why Perfect OB Wheel is your best choice of gestational calculator: 1) Input flexibility: Start with one of: • Last menstrual period (LMP) • Conception date • Estimated date of confinement/delivery (EDC) • Ultrasound dating: Number of weeks and days gestation as of a given date ("X Weeks"). 2) Input speed: Other wheels for the iPhone make you conform to them for entering your patient's information. Why not be able to choose based on how you are holding the phone and what else you are doing at the same time? • Use the numeric entry pad (0 3 3 0 2 0 0 8) and immediately see the results, OR • Spin the date wheel at the bottom of the screen and tap Next. 3) Thorough results: All the information you would expect from a classic wheel, plus more: • Estimated Due Date • LMP Date • Conception Date • 1st Trimester End Date • 2nd Trimester End Date • Gestational Age • Conceptional Age • Expected Fetal Length based on standard fetal growth curves • Expected Fetal Weight based on standard fetal growth curves ("How much does my baby weigh, doctor?") Results are relative to 'today' by default; this can be quickly changed to reflect any date by tapping the 'today' button and selecting a new date. 4) Accurate results: Perfect OB Wheel provides exact dates and accounts for all calendar variance, including leap years. 5) Persistence: Perfect OB Wheel remembers the date and date type you last used and restores them when launched to streamline your workflow. 6) Perfect OB Tracker upgrade: Available as an in-app purchase update, the Perfect OB Tracker lets you track any number of pregnancies, with at-a-glance due date and gestational age and one-tap access to all the data Perfect OB Wheel provides. A picture and text notes can be kept on each patient. Postpartum tracking is also available. Passcode locking is available for HIPAA compliance.
ObCalc
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ObCalc puts the calculators, scoring tools, and reference charts that obstetrics, maternal-fetal medicine, and labor & delivery teams reach for every shift into one fast, offline-first app. Every formula is sourced to published guidelines (ACOG, SMFM, CMQCC, NICHD) and built as a clinical tool first — clean inputs, clear interpretation, no clutter. OBSTETRICS • Bishop Score • Estimated Due Date — LMP, ultrasound, conception, ovulation, or IVF transfer dating • Pregnancy Re-dating (ACOG Committee Opinion 700) • Pregnancy Weight Gain Tracker • Urine Protein:Creatinine Ratio (UPCR) • VBAC Success Calculator — Grobman MFMU model • VBAC at Delivery Admission Success Calculator — Grobman MFMU model PERINATOLOGY / MFM • CVR (CPAM Volume Ratio) • Extremely Preterm Birth Outcome (NICHD) • Fetal Biometry Suite — Hadlock EFW, long-bone ratios, multi-panel z-scores and percentiles • Intrauterine Transfusion (IUT) Volume Calculator • MCA Doppler / PSV for Fetal Anemia • Neonatal Morbidity Risk • Ponderal Index • GDM Insulin Dosing • Life-Limiting Skeletal Dysplasia Screen • Twin Discordance • Umbilical Artery Doppler GENERAL • Anion Gap • Apgar Score • BMI • Iron Deficit • Peak Flow • Gestational Age (date difference) • Maternal Sepsis Assistant (qSOFA / Sepsis-3) • CMQCC Sepsis Screen THROMBOPHILIA • VTE Anticoagulation Dosing (ACOG Practice Bulletin 196) GENETICS • cfDNA PPV/NPV Calculator • Nuchal Translucency Percentile WHY CLINICIANS CHOOSE OBCALC • Offline-first — no connection needed on L&D • Fast, distraction-free interface — no ads, no tracking • One-time purchase. No subscription, no account required • Regularly updated with new tools and guideline changes • Built-in unit conversion and inline number-pad arithmetic on every input ObCalc is a clinical reference tool intended for use by licensed healthcare professionals. It does not replace clinical judgment, and results should be confirmed against current guidelines and your institution's protocols.
Screenshots
Verdict
The clearest difference is in-app purchases: ObCalc at none against Perfect OB Wheel's 1. Perfect OB Wheel's advantage is price ($1.99 vs $6.99) and update cadence (weekly vs every 5 weeks). On ads and device support 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
Perfect OB Wheel costs $1.99 and ObCalc $6.99 up front. Perfect OB Wheel sells 1 one-off in-app purchase. ObCalc asks for nothing beyond the download.
Perfect OB Wheel ships an update weekly, ObCalc every 5 weeks. The most recent releases landed on November 10, 2026 and November 11, 2026 respectively.
| Parameter | Perfect OB Wheel | ObCalc |
|---|---|---|
| Price | $1.99 — better | $6.99 |
| Rating | 4.9 (3.6K ratings) — better | — |
| Positive reviews | 83.0% of reviews | — |
| Number of ratings | 3.6K — better | — |
| Update frequency | Weekly — better | Every 5 weeks |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Best chart rank | #55 — better | — |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 13.0 — better | 26.0 |
| Further details — not scored | ||
| Size | 14 MB | 3 MB |
| Age rating | 17+ | 17+ |
| Developer | Evan Schoenberg | Code Nine Labs LLC |
Bugs and requests
Perfect OB Wheel
Reported bugs
3 issues- App crashes after update
- Delivered today button not working after upgrade
- Dates keep changing when entering info
Requested features
5 requests- Date-adjustment for women who have a five week menstrual cycle
- More fields for infant info, apgars and weight
- Ability to adjust cycle length
- Ability to type in a gestation and get a date or type in a date and get a gestation
- Calculate GA on a specific date
ObCalc
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Perfect OB Wheel
- Perfect OB Tracker$4.99
ObCalc
No in-app purchases
Questions
Is Perfect OB Wheel free?
Is ObCalc free?
Do Perfect OB Wheel or ObCalc have ads?
Which is updated more often, Perfect OB Wheel or ObCalc?
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