By sport
Triathlon Training Zones
Three sports, three anchors: swim CSS pace, bike FTP power, run VDOT pace, each with its own heart-rate cross-check.
Max Heart Rate Calculator
Your maximum heart rate is the highest your heart can beat in all-out effort. Age formulas estimate it: Tanaka gives 208 − 0.7 × age; the classic 220 − age tends to run high. At age 35 that is roughly 184 and 185 bpm, but the real value varies by ±10–12 bpm, so test it to be sure.
Heart Rate Zone Calculator
Your heart-rate zones are percentages of your maximum heart rate: Zone 1 is 50–60%, Zone 2 60–70%, Zone 3 70–80%, Zone 4 80–90% and Zone 5 90–100%. At a max of 185 bpm, Zone 2, the key aerobic-base zone, runs about 111–130 bpm. Spend most easy training in Zones 1–2.
Karvonen Heart Rate Reserve Calculator
The Karvonen formula sets zones from your heart-rate reserve: maximum minus resting heart rate. Target = intensity% × (HRmax − RHR) + RHR. With a max of 185 and resting of 50 bpm (reserve 135), 70% gives 0.70 × 135 + 50 ≈ 145 bpm. Because it uses your resting heart rate, it personalises zones to your fitness.
MAF 180 Formula Calculator
Maffetone's 180 Formula sets your maximum aerobic heart rate at 180 minus your age, adjusted for health and training status. A consistent, injury-free 35-year-old gets 180 − 35 = 145 bpm; the aerobic training range is then about 135–145 bpm. Train at or below it to build a strong, low-stress aerobic base.
LTHR Heart Rate Zone Calculator
LTHR zones anchor to your lactate-threshold heart rate, the heart rate you can hold for about an hour, instead of an age-estimated maximum. Find LTHR from the final 20 minutes of a 30-minute time trial. Friel's model then sets Zone 4 (threshold) at 94–99% of LTHR for cycling and 95–99% for running.
FTP Calculator & Cycling Power Zones
Functional Threshold Power (FTP) is the highest power you can hold for about an hour. The Coggan model sets seven zones from it: Endurance (Z2) is 56–75% FTP and Threshold (Z4) is 91–105%. At an FTP of 250 W, Z2 is 140–188 W, Z4 is 228–263 W, and Sweet Spot is 220–235 W.
Critical Power Calculator (CP & W′)
Critical Power (CP) is the asymptote of the power–duration curve, the highest power you can sustain almost indefinitely. From two maximal efforts, CP = (P1·t1 − P2·t2) ÷ (t1 − t2) and W′ = (P1 − CP)·t1. A 300 W 3-minute and 250 W 10-minute effort give CP ≈ 229 W with a W′ of about 12.9 kJ.
Running Power Zones Calculator
Running power zones anchor to your running Critical Power (CP), not cycling FTP. The two are not interchangeable. Stryd's five-zone model runs Easy below 80% CP up to Repetition above 115%. At a running CP of 280 W, Threshold tops out at 280 W and Repetition is open-ended above about 322 W.
VDOT Calculator & Running Pace Zones
VDOT is Jack Daniels' single running-fitness number, combining VO₂max and running economy from one race result. A 5 km in 20:00 gives a VDOT of about 49.8. From that one number the model derives every training pace, Easy, Marathon, Threshold, Interval and Repetition, so all your zones come from a single race.
Critical Swim Speed (CSS) Calculator
Critical Swim Speed is your swimming threshold pace, found from two time trials: CSS = 200 ÷ (t400 − t200) in metres per second, and pace per 100 m = 100 ÷ CSS. A 400 m in 6:00 and 200 m in 2:50 give a CSS of about 1.05 m/s, or roughly 1:35 per 100 m, your sustainable threshold pace.