TL;DR
For a fast pace with nothing to sign up for, use the Calc Garden running pace calculator: type a distance and finish time and it shows pace per km, pace per mile and average speed the instant you type, with the formula on the page. If you want training zones and race predictions from a recent race result, the McMillan Running Calculator is the deepest free tool. If you want a race-finish prediction and use Strava, its calculator is a good fit. This is not an "only free one" claim: McMillan, Strava and calculator.net are all free too. The choice is really quick pace versus race prediction versus full training paces.
What makes a pace calculator "best"
Every pace calculator runs the same core sum: pace is time divided by distance, and speed is distance divided by time. Because the arithmetic never changes, the tools differ on what they wrap around it, and that is where the right pick is decided. Three things matter most. The first is scope: do you just want today's pace from a distance and a time, or a race-time prediction, or a full set of training paces for easy, tempo and interval runs? The second is friction: does it work straight away for any distance, or is it locked to a preset list and nudging you to sign up? The third is transparency: does it show the formula and both units, or just hand back a number?
Those pull in different directions, so there is no single winner for everyone. A simple, browser-based calculator is unbeatable for a fast pace on any distance. A training-focused tool like McMillan is unbeatable for building a session plan around your current fitness. The table below lines up four free options against exactly these points so you can pick by what you actually need rather than by brand.
The best free running pace calculators compared
In the table a check means the tool does it cleanly, "Partial" means it does it with caveats, and a dash means it does not. The pricing row reflects each product as of 2026.
| Capability | Calc Garden | McMillan | Strava | Calculator.net |
|---|---|---|---|---|
| Price (as of 2026) | Free, no signup | Free (paid plans extra) | Free, no signup | Free, no signup |
| No account required | Yes | Yes | Partial | Yes |
| Pace from any distance and time | Yes | Partial | No | Yes |
| Pace per km and per mile together | Yes | Yes | Partial | Yes |
| Average speed in km/h shown | Yes | Partial | No | Yes |
| Race finish-time prediction | No | Yes | Yes | Partial |
| Training pace zones (easy, tempo, interval) | No | Yes | No | No |
| Formula shown on the page | Yes | No | No | Partial |
Read it honestly. McMillan wins where it counts for training: feed it a recent race time and it hands back a full set of paces for easy runs, tempo work, intervals and repetitions, plus race predictions across distances, which a plain pace calculator cannot do. Strava wins if your goal is a race-finish prediction and you already live in its app. Calculator.net is the strongest free all-rounder: it can solve for pace, time or distance and covers plenty of edge cases, though its interface is dense and ad-heavy. Calc Garden wins on speed and clarity for the most common job of all: turn one distance and time into pace per km, pace per mile and average speed, with the maths shown and nothing to sign up for.
Why a simple, no-signup calculator often wins
Most of the time a runner reaches for a pace calculator, the question is small and specific: I ran this far in this time, what was my pace, and what does that work out to per mile or in km/h? For that job, a training-plan engine or a race predictor is more machinery than the question needs, and a tool locked to preset race distances cannot even answer it for an odd 7.3 km loop or a 3-mile treadmill session.
Calc Garden's running pace calculator runs client-side in your browser: enter any distance and finish time, switch the distance between kilometres and miles, and it shows pace per km, pace per mile and average speed live as you type. The formula sits on the page, so you can see that pace is simply total time divided by distance rather than trusting a hidden calculation. The trade-off is honest and worth stating: it does not predict race times or build training zones, so if that is what you are after, McMillan is the better tool.
How to work out your pace by hand
The formula is pace equals total time divided by distance. Convert your finish time to a single unit first, usually seconds, then divide by the distance. A 10 km run in 55 minutes is 3,300 seconds over 10 km, which is 330 seconds, or 5 minutes 30 seconds, per kilometre. To convert to per mile, multiply by 1.609344, giving about 8 minutes 51 seconds per mile.
Average speed is the mirror image: distance divided by time. That same 10 km in 55 minutes is 10 divided by 0.9167 hours, roughly 10.9 km/h. Calc Garden's calculator lands pre-filled with a worked example so you can see all three figures at once, then change any input and watch them update. Two details keep the answer honest: make sure your distance and pace use the same unit before you compare, and remember that treadmill and GPS distances can differ by a few percent, which shifts the pace accordingly.
When to pick each one
Reach for McMillan when you are planning training and want paces for every type of session from your current fitness, or Strava when you want a race-finish prediction inside an app you already use. Reach for calculator.net when you need to solve for time or distance rather than pace, or want a single page that covers every variant.
Reach for the Calc Garden running pace calculator when you want a fast, clear pace from a distance and a time, in both units, with no signup. From there, two related tools round out a runner's numbers: the target heart rate calculator shows the beats-per-minute zones to train in, and the calories burned calculator estimates the energy a run costs. For the wider set of explainers, the guides index collects the rest, including what counts as a good BMI.