Men's fertility platform
Your fertility.
Tracked like a mission.
Most fertility apps weren't built for you. Kalcius is. Track your numbers, manage heat exposure, stay ahead of her cycle, and level up as a partner — all in one place.
01 / HARDWARE
The Kalcius Clip
A belt- or waistband-mounted BLE thermometer that logs heat exposure all day. Hot tubs, laptops, long drives — see exactly when you're cooking your odds, and fix it.
02 / INTEL
Know your numbers
Log semen analyses, hormone panels and vitals. Import from Apple Health. Watch trends, not one-off results — and know when a number is worth a conversation with your doctor.
03 / PARTNER OPS
Code Red. Code Orange.
Track her cycle, get advance warning on high-fertility windows and rough weeks, and get a daily play — a text to send, a move to make — keyed to what's going on and what worked last time.
04 / THE LEVERS
What actually moves the needle
The habits that shift the numbers, ranked by the strength of the evidence — heat, smoking, sleep, weight — with one-tap check-ins, streaks and badges. Where the trials say a supplement is a waste of money, the board says so.
05 / HER SIDE
Tracking her cycle isn't a secret you keep.
Cycle tracking in Kalcius starts as his private journal about showing up better. When he's ready, he can invite her in — and the link is built so that reading exactly how it works would only reassure her.
Her own account
She's invited by email and signs in as herself. Nothing is shared until she accepts — and the invite says exactly what he shares and what he doesn't, before she decides.
Nothing hidden
Everything shared is shown to her, unabridged, on her own page — his notes included. Anything he keeps back is named as not shared, category by category. There are no hidden extras.
Either of you can end it
One tap, either side, no negotiation. If what's shared ever changes, she's told — a change is announced, never silent. And both accounts can export or erase their data at any time.
06 / THE LIBRARY
Straight answers, free to read
The Learn library is public — no account, no paywall. Evidence described honestly, including when the honest answer is “save your money”.
Testing · 2 min
How to read a semen analysis
The report is a wall of numbers with no explanation. Here's what each one means, what the reference ranges actually are, and what they aren't.
Lifestyle · 2 min
The three-month rule
Every change you make today shows up in a semen analysis about three months from now. Understanding this one lag explains half of fertility tracking.
Supplements · 2 min
Supplements: an honest guide
A billion-dollar industry runs on male fertility anxiety. What the trials actually found, what might be worth it, and when to save your money.
07 / THE DEAL
The core is free
Free, forever
Tracking and logging, cycle predictions and the code alerts, the levers board with streaks and badges, the partner link, and the full Learn library. Your data is always retained, always exportable, always yours to erase.
Kalcius Plus
The deep end: full history on the device and body charts (free keeps the last 7 days in view — nothing is deleted, upgrading unlocks what was already yours), the AI-drafted plays and composer, and the weekly insight over your trends. Cycle history stays free: predictions need it, so it was never for sale.
Kalcius Clip — coming soon
Continuous heat-exposure logging. Two-week battery. USB-C. Syncs to your phone over Bluetooth. Clip it to your belt or waistband and forget it's there.