Stack vs Laktic Pace Calculator

Stack is a habit tracker with a finish line. Three habits. Ninety days. Then it is done. The stack ships, archives, and you start fresh. The cap of three and the ninety days are not limits to pay past. They are the point. Most habit apps are built to keep you forever. Stack is built to end. - Three habits. No more. The limit is the feature. - Ninety days. A clean quarter, then a finish line. - One honest skip a week. It holds your streak but shows as a skip, never a fake fill. - The grid is the app. Ninety days of dots, filled in by hand. - A home-screen widget with today's three. Tap to mark. - Built in Liquid Glass for iOS 26. No accounts. No subscription. No analytics. Zero data collected. Pay once. It is yours. From hsla0001, an independent studio in New York. Void captures. Loop times. Protocol scores the room. Stack holds intent.

Today's threshold paces, adjusted for the heat. Enter a race PR, track or road, and get LT1, Sub-T and LT2 ranges slowed for the temperature and dew point at your track, now or at practice time. Coaches: add your roster, write a note, and share the board as a card. Enter a 5000m, 3200m, 3000m, 1600m, mile or 1500m PR, or a 5 mile, 10K, half marathon or marathon PR, and the app computes the Track and Road Performance training zones: Easy, Long Run, Steady, and the three threshold zones LT1, Sub-T and LT2, with race-pace rows for road distances. Miles or kilometres, your choice. Get today's temperature and dew point for your location, pick a practice time for that hour's forecast, search a city or ZIP, or type the numbers yourself, and every pace is slowed by the heat penalty. The adjustment is scaled by rep length. Short threshold reps with recovery build less heat load than continuous running, so 1–3 minute reps take half the penalty, 4–6 minute reps three-quarters, and 7–10 minute reps and continuous runs the full amount. Within each threshold zone, short reps sit at the fast end of the range, medium reps in the middle, and long reps at the slow end. Every pace shows the per-mile range and the seconds-per-400 m split, so it goes straight to the track. For coaches: keep a roster of athletes on your phone and build a workout board for today's conditions. Pick a zone and rep length and see every athlete's heat-adjusted range, fastest first, filtered by group. Write a note on the board and share it as a card, along with today's paces, the heat, a new PR or a finished session. Log a session: type your reps and see hit, hot or cold against today's band. Export the roster as a file, import one from an assistant coach, or copy a share link that opens the same roster in the web version. How the heat model works: heat score = temperature °F + dew point °F. At 100 or below there is no adjustment. The penalty rises to 10% at 180. Above 180 the app tells you running is not recommended and shows paces at the cap for reference only. Privacy: your location is used only to fetch the weather and the town name. Athlete names and PRs stay on your device unless you export or share them; share cards are drawn by our server from the numbers on screen and are not stored. Sign-in is optional. No tracking, no ads. Training guidance, not medical advice. Use judgment in extreme conditions. Pace engine: Track and Road Performance. Weather data by Open-Meteo.