Period tracker questions, answered
In short: Short, sourced answers to the questions people ask about period trackers: privacy, accounts, accuracy, irregular cycles, perimenopause, sharing with a partner and cost. Each page opens with the answer, shows its sources and the date they were checked, and links to the longer Splash library. Written by the Splash team; updated 28 October 2026.
Is my period tracker data private?
It depends on the app. A 2022 ORCHA review of 25 period apps found 84% sent data beyond the developer’s own systems, and Mozilla’s July 2026 review of six trackers found only Stardust sending sensitive health data to another company. The most private choices keep data on your device without an account: Euki, drip and Splash, which adds optional end-to-end encrypted sync.
What is the best period tracker for irregular periods in the UK?
Choose a tracker that shows ranges instead of one date, lets you log symptoms beside dates, and can summarise them for your GP. Splash widens its range when cycles vary, has PCOS and perimenopause settings, and makes its doctor report free; Flo keeps its doctor report in Premium. The NHS calls periods irregular when the gap is under 21 or over 35 days.
Is there a period tracker that works without an account?
Yes. Splash, Euki and drip work with no account, and Flo offers an Anonymous Mode that needs no email. Without an account your data is saved on your phone, so back it up: Splash lets you save a backup file, or turn on end-to-end encrypted sync later. Clue needs an account to share your cycle.
How accurate are period tracker predictions?
Period apps predict your next period reasonably when your cycles are steady and poorly when they are not, and calendar-only fertile-window predictions are unreliable. A 2016 study found only a small minority of apps and websites identified the fertile window correctly. In Splash’s own tests on made-up data, the real start fell inside the range 82% of the time for regular cycles.
Which period tracker is best for perimenopause?
Use a tracker that copes with irregular cycles and lets you log hot flushes, sleep and mood, then summarise them for your GP. Splash’s perimenopause mode widens predictions, does not nag about late periods and tracks HRT, free; Clue’s Perimenopause mode is part of Clue Plus. NICE says a GP can usually diagnose perimenopause from symptoms if you are over 45.
How can I share my cycle with a partner safely?
Share only what you choose, use end-to-end encryption, and keep the ability to pause or stop at any time. In Splash, a QR code carries a key only you and your partner hold; you tick the categories, preview what they will see, and can pause, stop or set an expiry. Clue keeps sharing your own cycle in Clue Plus; basic Flo for Partners is free.
What is the best free period tracker in the UK?
Free choices in the UK are Apple Cycle Tracking (built into iPhone), Euki and drip (free, open source, local-only) and Splash (free, no paid tier, no account). Flo and Clue are free to start but keep some features in Flo Premium and Clue Plus. Natural Cycles is a paid contraceptive app. We make Splash, so every claim about the others is sourced.
Flo vs Clue: which period tracker is better?
Flo and Clue both have free versions and paid tiers. Flo has the bigger expert library, a community and an Anonymous Mode; Clue is Berlin-based under GDPR and science-led, and scored 8 out of 10 against Flo’s 7 in Mozilla’s July 2026 review. Clue Plus holds sharing, Conceive and Perimenopause; Flo Premium holds courses, a Health Assistant and the doctor report. Neither is better for everyone.
More: the Splash FAQ · compare period trackers · the health library · free calculators
Better still, try it
Free, no account, and your cycle stays on your phone.