How Lova
Calculates Your Cycle
Transparent, science-based predictions that get smarter with every cycle you track. No black boxes—understand exactly how your data becomes predictions.
±1 Day Accuracy
After 12+ cycles
On-Device
All local processing
What We Calculate
Four key predictions that help you understand your cycle
Cycle Length
Average of your last 3-6 cycles, weighted toward recent data for accuracy.
Ovulation Day
Estimated 12-16 days before your next predicted period, refined with BBT data.
Fertile Window
5 days before ovulation through ovulation day, accounting for sperm survival.
Next Period
Based on your average cycle length from the start of your last period.
What Affects Your Predictions
Multiple data points combine to create personalized, accurate predictions
Historical Cycle Data
More cycles = better predictions. Lova uses 3-6 months of data when available.
Cycle Regularity
Consistent cycles get tighter prediction windows; irregular cycles get wider ranges.
BBT Data
Temperature shifts confirm ovulation and refine future predictions.
Symptom Patterns
Cervical mucus, mittelschmerz, and other symptoms help pinpoint ovulation.
Adaptive Weighting
These weights adjust based on your data quality. If you track BBT consistently, its weight increases. If you have few cycles logged, historical data gets weighted less until you build a baseline.
Accuracy Improves
With Every Cycle
Lova learns your unique pattern over time. The more you track, the better your predictions become.
Learning phase—predictions improve quickly
Good baseline established
Personalized predictions
Maximum accuracy for your unique pattern
The Science Behind the Predictions
Lova uses established reproductive science combined with statistical methods
Cycle Length Calculation
Method: Weighted moving average
Data used: Last 3-6 recorded cycles
Weighting: Recent cycles count more (exponential decay)
This accounts for natural cycle variation while remaining responsive to changes in your pattern.
Ovulation Estimation
Method: Luteal phase reverse calculation
Assumption: Luteal phase is 12-16 days (average 14)
Refinement: BBT shift confirms actual ovulation
Unlike follicular phase, luteal phase length is relatively consistent for each person.
Fertile Window
Method: Sperm survival + egg viability window
Start: 5 days before estimated ovulation
End: 24 hours after ovulation (egg lifespan)
Sperm can survive up to 5 days; the egg is viable for about 12-24 hours after release.
Confidence Intervals
Method: Standard deviation of historical cycles
Display: Shown as date ranges, not single dates
Adjustment: Wider for irregular cycles
Honest uncertainty communication—we show ranges, not false precision.
All Calculations Happen On Your Device
All predictions are computed locally on your device. When you sync, your data is encrypted before leaving—only you have the key. Lova never sees your unencrypted health data.
Frequently Asked Questions
Why are my predictions sometimes wrong?
How does Lova handle irregular cycles?
Do I need to track BBT for accurate predictions?
How is fertile window calculated if I'm trying to conceive?
Why does the app ask for my last few periods?
Start Building Your Cycle History
The best time to start tracking was last month. The second best time is today. More data means better predictions—begin your journey to cycle awareness.