Half Marathon Training Plan
A half marathon training plan is a 12-week structure that takes you from your current fitness to a PR on race day. It has four phases: base, build, sharpen, and taper. It scales mileage gradually, places specific workouts at the right intensity, and peaks the long run at 12 to 14 miles before backing off to let you race fresh.
This guide gives you the structure, the paces, and the weekly mileage targets by goal time. Every pace recommendation is anchored to the VDOT system, which calibrates training to your current fitness rather than your goal fitness. That distinction matters more than most runners realize.
Who this plan is for
You’ve raced a 5K or 10K within the last six weeks. You’re running consistently — three to four days a week minimum, ideally five — and you can already finish an eight-mile run without walking. You’re not in the middle of an injury, and you can give the plan twelve uninterrupted weeks.
If that describes you, this plan works. If you’re shorter on base than that, spend four to six weeks just running consistent easy miles before starting. The plan assumes you arrive with the aerobic foundation in place.
The plan also assumes you have a recent race result you can feed into a VDOT Calculator. Without that, the paces below are guesses. With it, they’re calibrated.
What a half marathon plan must contain
A working half marathon plan does five things. Skip any of them and the plan stops being a plan.
It builds aerobic capacity through easy mileage. The bulk of your weekly volume — 70 to 80 percent — is run at genuine easy pace, not the gray-zone tempo most runners default to. This is the work that grows capillary density, strengthens the heart, and lets you process oxygen efficiently over 13.1 miles.
It develops lactate threshold through tempo work. Threshold pace is the engine of half marathon performance. The half marathon is run very close to your threshold — usually within 10 to 15 seconds per mile — and raising that threshold is the most direct way to drop your finish time.
It develops VO2 max through interval work. Interval sessions at 3K-5K effort raise the ceiling on your aerobic capacity. Without them, threshold improvements plateau.
It includes a progressive long run. The long run grows from your current capacity up to 12 to 14 miles. This builds the structural durability and glycogen storage you need to hold pace in the final miles.
It includes race-pace work. By weeks six through nine, you should be running 4-8 mile segments at goal half marathon pace. Race pace must become familiar before race day, or you’ll arrive at the start line guessing.
The 12-week structure
The plan breaks into four phases.
Base (weeks 1-4): Build aerobic mileage. Easy runs, strides, one moderate workout per week. You’re laying foundation, not testing yourself.
Build (weeks 5-9): Add threshold and VO2 max work. Long runs grow to 11-12 miles. This is where fitness actually changes.
Sharpen (weeks 10-11): Race-pace specificity. The longest long run lands here (12-14 miles). Workouts shift toward goal-pace work.
Taper (week 12): Cut volume by 40-50 percent while keeping some intensity. You’re banking freshness, not building anything.
Here’s how the weeks lay out by phase, with the peak long run inside the sharpen block:
| Phase | Weeks | Long run peak | Workout focus |
|---|---|---|---|
| Base | 1-4 | 8-10 mi | Easy mileage, strides, one moderate run |
| Build | 5-9 | 11-12 mi | Threshold + interval work |
| Sharpen | 10-11 | 12-14 mi | Goal-pace long runs, race-pace tempo |
| Taper | 12 | 6-8 mi | Short race-pace touches, full recovery |
Weekly mileage by goal time
Mileage scales with goal time. A sub-1:30 half requires running enough volume to sustain 6:50 per mile for 13.1; a sub-2:15 half needs less. The numbers below are peak weekly mileage during the build and sharpen phases. Base weeks run about 70 percent of peak; taper week runs about 50 percent.
| Goal time | Peak weekly mileage | Long run peak | Days per week |
|---|---|---|---|
| Sub-1:30 | ~45 mpw | 14 mi | 6 |
| Sub-1:45 | ~38 mpw | 13 mi | 5-6 |
| Sub-2:00 | ~30 mpw | 12 mi | 5 |
| Sub-2:15 | ~25 mpw | 12 mi | 4-5 |
These are targets, not requirements. If you’ve been running 20 miles per week and your goal is sub-2:00, you don’t jump to 30 in week one. You build toward 30 over the first six weeks. The 10 percent rule applies — increase weekly volume by no more than 10 percent week-over-week, with a step-back week (about 80 percent of the prior week) every fourth week.
Workouts by VDOT zone
A Pace Calculator translates your VDOT into actual minutes per mile for each zone. The numbers below show what those zones look like at a VDOT 45 (roughly a 20:30 5K, a 1:35 half projection) so you can see the relative gaps.
Easy pace (E): 8:45-9:35 per mile. The pace where you can hold a full conversation. Most of your weekly volume lives here.
Marathon pace (M): 7:50 per mile. Used in long-run finishes and as a “moderate” stepping stone.
Threshold pace (T): 7:15 per mile. Run as cruise intervals (4-6 x 1 mile with 60 seconds rest) or steady tempos of 20-40 minutes.
Interval pace (I): 6:40 per mile. Run as 800-1200m repeats with equal-time recovery, totaling 4-6 kilometers of fast running.
Repetition pace (R): 6:05 per mile. Run as 200-400m repeats with full recovery, used to maintain leg speed and economy.
A typical week in the build phase looks like this for a sub-1:45 runner:
- Monday: rest or 30 min easy
- Tuesday: 6 mi with 4 x 1 mi at T pace, 60 sec jog recovery
- Wednesday: 6 mi easy
- Thursday: 7 mi with 5 x 1000m at I pace, equal-time jog
- Friday: 5 mi easy + 6 strides
- Saturday: 4 mi easy
- Sunday: 11 mi long run, last 2 at M pace
That’s 39 miles. Two quality sessions, one long run, four genuine easy days. The training pace calculator guide explains why the easy days have to actually be easy.
The peak weeks
Weeks 8 through 11 are where the plan asks the most of you. Mileage is at or near peak. The long run hits its maximum. Race-pace work shows up inside both the long run and the tempo workouts.
A representative peak week (sub-1:45 goal, VDOT 45):
- Tuesday: 7 mi with 5 x 1 mi at T pace, 60 sec jog
- Thursday: 8 mi with 6 x 1000m at I pace, equal jog
- Sunday: 13 mi long run, middle 6 at goal half marathon pace (7:55)
That Sunday run is the closest you’ll get to race day before race day. It tells you whether your goal pace is honest. If you hit those middle 6 miles and finish feeling controlled, your goal is real. If you fall apart at mile 9, your goal is too aggressive — adjust before week 12.
Cross-check by running a tune-up 5K or 10K in week 8 or 9 and feeding the result into the Race Time Predictor. If your predicted half is 4-5 minutes faster than your stated goal, you’re sandbagging. If it’s 4-5 minutes slower, your goal needs revisiting.
Long run progression
The long run grows roughly 10 percent per week with step-back weeks every fourth week. A sub-1:45 runner’s progression:
- Week 1: 8 mi
- Week 2: 9 mi
- Week 3: 10 mi
- Week 4: 7 mi (step back)
- Week 5: 10 mi
- Week 6: 11 mi
- Week 7: 12 mi
- Week 8: 9 mi (step back)
- Week 9: 12 mi
- Week 10: 13 mi
- Week 11: 13 mi with M-pace work
- Week 12: 8 mi (taper)
All long runs are at easy pace unless specified. Easy pace on long runs is critical — runners who race their long runs accumulate fatigue without the durability benefit the long run is supposed to provide. The slow miles are doing structural work; let them.
Race-pace work
Goal half marathon pace lives between Threshold (T) and Marathon (M) pace. For most runners it sits within 5-15 seconds per mile of T pace. You should be running goal-pace segments by week 6 at the latest.
The progression:
- Weeks 6-7: 2-3 miles at goal pace, embedded in a longer run
- Weeks 8-9: 4-5 miles at goal pace
- Weeks 10-11: 6-8 miles at goal pace inside the long run
When you race your goal pace in training, it stops being abstract. Race day becomes execution, not discovery. The half marathon negative split strategy guide and the half marathon pacing guide cover how to translate those rehearsed paces into a race-day execution plan. Both lean hard on the idea that the first 5K should feel restrained — almost too easy — and that the second half is where you collect time.
A Race Split Planner turns your goal time into mile-by-mile splits you can print and carry. Most runners need a physical reference for the first three miles, because adrenaline and crowd pacing will pull you 15-20 seconds per mile too fast otherwise.
Taper
The taper is one week. Two weeks is too long for a half marathon — you start to lose sharpness without meaningful additional recovery. One week is enough to clear cumulative fatigue while keeping your turnover intact.
Cut total volume to 50-60 percent of peak. Keep one short tempo or interval session early in the week (e.g. 3 miles with 4 x 400m at I pace). Keep one set of strides midweek. Drop the long run to 6-8 miles at easy pace, four to six days out from the race.
Don’t add anything new during taper. No new shoes, no new gels, no new pre-race routine. The taper is for executing what you’ve already practiced.
Common errors
Running easy days too hard. This is the single most common mistake. Easy means easy. If your VDOT 45 says 8:45-9:35 for easy pace and you’re running 8:00, you’re not running easy. You’re running gray-zone moderate, which fatigues you without producing the adaptations easy pace is designed to produce.
Skipping the step-back weeks. Step-back weeks aren’t optional. They’re where adaptation consolidates. Runners who skip them accumulate fatigue and arrive at the peak weeks too tired to execute the workouts.
Treating the long run as a race. The long run is aerobic work. Pushing it 15 seconds per mile faster than easy pace doesn’t make it more effective — it makes it harder to recover from, which compromises the next quality session.
Picking a goal time based on a years-old PR. Recalibrate using a recent race. A 5K from 18 months ago doesn’t tell you what your current half marathon fitness is.
Cramming missed workouts. A missed Tuesday workout doesn’t get rescheduled to Wednesday next to the long run. It’s gone. Move on. The plan is designed around recovery windows, and stacking sessions to catch up breaks those windows.
Tapering too aggressively or not at all. Cutting volume by 70 percent leaves you feeling flat on race day. Cutting volume by 10 percent leaves you tired. Aim for the 40-50 percent range.
If you want all the pace math, the VDOT zones, the split sheets, and the predictor in one place that works offline, Pacesmith bundles every tool you need for half marathon training into a single iOS app for a one-time $1.99. No subscriptions, no account, no internet required on race morning.