These free running calculators turn a time, a distance or a heart rate into something you can train and race on, and each one tells you what the number means for you.
Pacing and racing
- Pace calculator: work out the pace you need for a finish time, or the finish time a pace gives you.
- Race predictor: turn one recent race into realistic times at every distance.
- Marathon pace chart, half marathon pace chart, 10K pace chart and 5K pace chart: every finish time with its pace and splits, ready to print or save to your phone.
How good is my time?
- Age grade calculator: see how your run compares with the best possible for your age and sex.
- Good 5K times, good mile times, good 10K times, good half marathon times and good marathon times: find where your time ranks at your age.
Qualifying for the big races
- Boston qualifying times: check your standard and see how far under it recent qualifiers had to run.
- London Good for Age: check your standard and your odds of a place.
Training zones
- VDOT calculator: get easy, marathon, threshold and interval paces from a recent race.
- Heart rate zones: set zones from your threshold heart rate, or from your maximum and resting heart rate.
- Running power zones: set power zones from your critical power.
Where the numbers come from
Age grading uses the 2025 road factors published by Alan Jones and Howard Grubb. Race predictions use Pete Riegel’s formula and Jack Daniels’ VDOT tables. Every tool shows its source beneath the result, and the tables are checked against the originals each year. Once you know your numbers, a 5k training plan or a running watch that follows the same zones will put them to work.
Quick answers
Are the running calculators free?
Yes. Every calculator is free and needs no sign-up. Nothing you type is uploaded: the sums run in your browser, on your own computer or phone. If the calculators help you, you can say thank you by buying me a coffee or becoming a subscriber.
Which calculator should I start with?
Start with the pace calculator if you have a goal time, the race predictor if you have a recent race, and the age grade calculator if you want to know how good a time really is for your age.
How accurate are the race predictions?
Predictions are most reliable between similar distances, such as 10K to half marathon, and least reliable when you jump from a 5K to a marathon without long runs behind you. The race predictor explains the range for your result.
Do the calculators work on a phone?
Yes. Each one is built for a phone screen first, so you can use them at the track, on a treadmill or in the car park before a race.
Small things I always use
- Garmin 90-degree charging adapter: Charges your Garmin from any USB-C cable. Essential when travelling. I use one.
- Body Glide: The blue anti-chafe stick swimmers and runners carry. I use it.
- Speedo earplugs: Fewer ear infections and no cold-water dizziness. I use them.
- Dryrobe Advance: My winter changing robe for open-water swims. I use one. A cheaper option is the AONYIYI changing robe.
- Maurten: Race fuel that stays easy on the stomach. I use them.
- Beet It Sport nitrate shots: Beetroot shots I take in the days before a race. I use them.
- Garmin charging puck: The quickest way to top up before a session. I use one.
- Injinji: Toe socks that stop rubbing, so you run more. I use them.
- Ultimate toe protectors: Stop black toenails on long runs. They work. I use them.
- Compressport R2 v2 calf sleeves: My calf sleeves of choice. I use them.
- Cellucor C4: My pre-workout before hard sessions.
- TPU tubes: Schwalbe Aerothan, Tubolito and Pirelli SmarTube. Light, tiny spares. I use all three.
- G8 insoles: Adjustable insoles that are good. I use them.
- Cycplus Cube: A 97g electric pump that gets a road tyre rideable in two minutes. I carry one. 5% off with code THE5KRUNNER.
Watches and sensors
- Polar H10: My daily driver for waking HRV.
- Polar Verity Sense: My backup arm-worn HR sensor.
- Nomad bedside charger: Charges my iPhone and Apple Watch overnight. I use it, and many of their bands.
- Train.Red: The best muscle oxygen sensor I’ve used.
- Tymewear: Accurate heart rate and reliable ventilatory zones. I use it to pace endurance rides over an hour.
- Garmin Forerunner 970: A pro-grade triathlon watch. I use this.
- Apple Watch Ultra 4: My daily smartwatch. No phone needed on rides.
- Garmin Fenix 9 Pro: I’ve just bought one.
On the bike
- Continental GP5000 for everyday riding, and Aero 111 on the front for special occasions.
- Helmets: Specialized S-Works Evade 3 for road riding, and Rudy Project Wing for TT-style races. I use both.
- Ravemen FR300: A front light that mounts under your Garmin or Wahoo. I use one.
- Ravemen FR1000: The light and the computer mount in one unit, so nothing else goes on the bars. Better than mine.
- Ravemen FR1500SE: 1,500 lumens hanging under your Garmin, for proper night rides.
- Ravemen FR500: A brighter FR300 with the same mount.
- Wahoo TRACKR Radar: I use it on one bike and Varia on the other. They perform the same.
- Garmin Varia RTL515: Radar that warns you of cars from behind. I use this model.
- Wahoo ELEMNT Roam 3: The bike computer that’s easy to use. I use mine on most rides.
- Favero Assioma Pro RS2: Accurate power pedals that swap easily between bikes. I use this model.
Home and indoor training
- NPE Runn: Makes my basic treadmill smart, sending more accurate speed and distance to my watch and Zwift. I use it.
- Google Wifi: Keeps Zwift connected in my pain cave. I use it.
- Apple TV 4K: Zwift on the big screen. I use two.
- Google Nest Doorbell (wired, 2nd gen): My video doorbell, running in both Google Home and Apple Home. I use it.
Health, recovery and sleep
- FreeStyle Libre 3 Plus: Shows how my blood sugar responds to diet.
- hDrop: Measures my sweat loss in summer and indoors.
- Fourth Frontier Zone: Checks my heart under load in hard sessions.
- Kineon MOVE+: Red and infrared light for sore knees, Achilles and other joints after hard training. I use it.
- Oura Ring 5: My partner’s recovery tracker of choice.
- Eight Sleep: A cooling mattress cover my partner and I use nightly.
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Written by real people, with AI assistance. Fact-checked and verified for originality. See the Editorial Policy. FTC: Affiliate Disclosure — some links pay commission. As an Amazon Associate, I earn from qualifying purchases.
