20 Week Half Marathon Training Plan (Free, Personalized)

This 20-week half marathon plan runs 4 days a week (Tue, Thu, Sat and a Sunday long run), peaks at 25 miles in week 15, builds the long run to 14 miles and tapers for 2 weeks. Easy running only, the right call for a first half marathon. Use the table as is, print it, or generate the same plan around your own race date and run days.

The 20-week half marathon plan, week by week

Totals are the sum of the week's runs, rounded to a whole mile; day distances are rounded to a tenth of a mile. Rest days show the default Tue/Thu/Sat/Sun pattern; the generator moves sessions to the days you pick.

Phases of the plan

• Base, 6 weeks. Base: easy running only, the long run grows a little each week and every fourth week steps back to absorb the work.
• Build, 6 weeks. Build: volume keeps rising; experienced runners add one tempo or interval session a week, beginners keep everything easy.
• Peak, 6 weeks. Peak: the longest runs of the plan and the highest weekly volume, still with a cutback week.
• Taper, 2 weeks. Taper: volume and the long run step down so you arrive at the start line fresh; race week ends with a short run.

Run types

• Easy run. Relaxed, conversational. Most of the plan.
• Long run. Steady and conversational, the one run that builds race endurance. Always on your long-run day.
• Tempo. 1 mile easy, the middle miles comfortably hard, 1 mile easy. Marathon and half plans, experienced runners only.
• Intervals. 5 × 400 m (6 × in the peak) with jog recovery; 5K and 10K plans.
• Rest. Days without a run. The generator respects the days you choose.

How the numbers are set

• Phases by share of plan length: Base = first 30 % of weeks, Build = next 30 %, Peak = the rest up to the taper, Taper = last 3 weeks (marathon), 2 (half), 1 (10K and 5K). A short plan still gets at least one Build and one Peak week
• Starting weekly volume = max(current weekly mileage you enter, run days × 4 mi for the marathon, × 3.5 for the half, × 2.5 for the 10K, × 2 for the 5K). Week 1 in a table can be a mile or two higher: no easy run is shorter than about 2 mi
• Target peak week for a first-timer: 35 mi (marathon), 25 mi (half), 20 mi (10K), 15 mi (5K); 25 % higher with some experience. Weekly growth (3 % to 15 %) is solved so the highest week before the taper hits the target. A plan too short for that peaks lower, as the table shows
• Every 4th week is a cutback week at 82 % of the previous week, but never in the taper or the two weeks before it
• Long run grows each week toward its cap (20 mi marathon, 14 mi half, 9 mi 10K, 6 mi 5K) by 4 % to 20 % a week and drops to 85 % on cutback weeks. In a short plan it can stay below the cap
• Taper: about 75 % of the peak week in the first taper week, then about 60 % and 45 % (marathon) or 50 % (half). The 5K and 10K taper lasts one week. The long run drops to 70 % and, in a longer taper, to about 60 % in race week. Low-mileage plans cut a little less

How this plan differs

The 20-week half marathon plan set against the 18-week plan and the 24-week plan, its closest neighbours on the site. All numbers come from the engine that builds the table above.

• Length and phases. 20 weeks: 6 base, 6 build, 6 peak, 2 taper. The 18-week plan is 2 weeks shorter (5 build, 5 peak); the 24-week plan is 4 weeks longer (7 build, 7 peak).
• Starting point. Week 1 has 14 miles over 4 runs and a 4-mile Sunday run, the same as the 18-week plan.
• Peak and total. The biggest week is 25 miles (week 15), and the plan adds up to 375 miles. 18-week plan: 25 at week 16, 54 miles fewer in total; 24-week plan: 25 at week 19, 77 miles more in total. Sunday distance reaches the 14-mile ceiling in week 18.
• Hard sessions. None: all 80 runs are easy days or the Sunday run. 18-week plan: no hard sessions; 24-week plan: no hard sessions.
• Taper. 19 → 13 miles over the last 2 weeks, with 5.9 miles on race-week Sunday; the 24-week plan tapers 19 → 13.

Frequently asked questions