How far should I be able to run?

Updated October 6, 2026 · By Oktay Kurt, developer of Runked

"How far should I be able to run" almost always gets answered with someone else's number: a marathoner's weekly mileage, a colleague's parkrun time, a training plan built for a different runner. None of that is useful without knowing one thing: how long has the person asking actually been running, consistently, without long gaps? That's the honest starting point, and it's the one below.

What Couch to 5K actually prescribes, week by week

A publicly documented beginner running structure is the NHS's Couch to 5K running plan, a free nine-week programme built specifically to take someone from no running background to continuous running. Each session is defined in minutes of running and walking; the plan carries no distance target. The week-by-week structure is public:

That 30-minute finish is why the programme is named Couch to 5K: 30 minutes of running lands close to 5 kilometers at a beginner's pace. It isn't exact; pace varies enough between beginners that 30 minutes might cover 4.5K for one person and 5.5K for another, which is the point of building the plan around time instead of distance in the first place. If you're earlier than week 9, the honest target is the minutes on the schedule.

Building past 5K: how much distance to add

Once continuous running is established, two separate questions come up: how long any single run should be relative to the week's total, and how fast the week's total itself should grow. Both have named, attributed guidance, and the second is less settled than its reputation suggests.

On the first question, Canadian Running Magazine (Paul Baswick, 2023) reports exercise physiologist Jack Daniels' two-tier cap on the long run: runners covering fewer than 64km (40 miles) in a week "should limit their long run to 30 per cent of their total weekly distance." Above that weekly volume, the same article reports, the long run should not exceed 25 per cent of the week's total distance, or 150 minutes, whichever comes first. A runner on 20 weekly miles falls in the first tier, so the long run tops out around 6 miles, a ceiling on any single session applied week after week regardless of how good that run feels partway through.

On the second question (the "10% rule": never raising total weekly mileage by more than 10% over the week before), the evidence is thinner than the rule's reputation. A 2008 randomized controlled trial by Buist and colleagues, published in the American Journal of Sports Medicine, put 532 novice runners on either a standard 8-week programme or a graded 13-week programme built around the 10% rule, training all of them toward the same 4-mile event. Injury rates came back almost identical: 20.8% on the 10%-rule programme versus 20.3% on the standard one. A 2025 cohort study of 5,205 runners in the British Journal of Sports Medicine (Frandsen and colleagues) separated two versions of the same threshold. Overuse injury rates rose significantly when a single session went more than 10% past a runner's own longest run of the previous 30 days, with an adjusted hazard rate ratio of 1.64 for jumps in the 10-to-30% band, measured against runners who held steady or increased by up to 10%. For the week-to-week mileage ratio, the version Buist's trial randomized people onto, the same study reported no relationship at all. Applying 10% to a single run has data behind it. Applying it to a weekly total is a convention, so pair it with a fitness and fatigue read as ambition builds. How the non-running days in that week are scheduled is a separate question, and rest days for runners lines up what named plans give at each level.

How far before a half marathon

Hal Higdon's Novice 1 half marathon plan, a structured plan for first-time half marathoners, runs 12 weeks: the opening long run is 3–4 miles, and the peak long run (reached in week 11) is 10 miles, short of the full 13.1-mile race distance. Runners cover that last 3.1 miles for the first time on race day itself, carried by the taper, pacing and race-day atmosphere. Higdon's page states that the schedule "assumes you have the ability to run 3 miles, three to four times a week" before week one.

There's no "should": only your own last few weeks

Every number on this page is a published programme or someone else's cohort average; none of them describes any single runner reading it. A more useful daily question than "how far should I be able to run" is how this week compares to your own last few. In Runked, the running rank only moves on your own runs: compare this week to your own last one, not to a published programme's schedule.

Build the distance, don't guess it

• Follow a plan. Runked's 5K training plan and half marathon training plan structure the week-by-week buildup so distance isn't left to feel.
• Make consistency the actual goal. A running streak rewards showing up, which is what training age is really measuring.
• Know the actual number. Runked's race time predictor estimates your current 5K, 10K, half and marathon numbers from recent training.
• Track your own trend. Your recent weeks are a better daily signal than any programme's fixed schedule.

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