SI Roadshow Competition

On World Metrology Day 2019 the International Primary Kilogram (IPK) held in a vault in France will no longer be the world’s standard reference for mass. Since metrication in 1972, New Zealand has been flying a 1 kilogram mass standard over to France every five years to be compared against the IPK. MSL will instead be referring to a defined constant of nature making our current reference 1 kilogram standard redundant. So, with the corner of its passport now clipped, we decided to ‘throw it away’ in true Kiwi competition style.

Click to watch the video
(external link)

Julia Ratcliffe, New Zealand’s Commonwealth gold medallist hammer thrower definitely ‘measures up’ for the job of throwing the MSL’s 1 kilogram mass standard away! Julia normally throws a 4 kilogram hammer, so how far can she throw our 1 kilogram mass standard hammer?

Our MSL scientists were let out of their laboratories to complete some field experiments and collect the measurement data.

(external link)  Click on the above image to watch the video and see how they got on.




Distance – throw 1

 60.81322 m

Distance – throw 2

 62.91662 m

Distance – throw 3

 62.64843 m

Distance – throw 4

 64.75877 m

Mass of 4kg hammer plus handle

4000.43 g


21.8 °C

Relative Humidity

69.7 %


101.4 kPa

UV index


Wind speed


*Standard Wellington Gust

Julia’s average throw of the 4 kilogram hammer is 62.78426 m.

The official, and very likely only, 1 kilogram mass standard hammer in the world, weighs in at an impressively accurate 1000.00 g with handle. 

Based on all the information provided, the Measurement Standards Laboratory challenges you to give us your best calculated guess on the distance it travelled.  All throws were completed within a 30-minute period and your calculated guess must be in metres and provided to 5 decimal places.

Official Entry Form

Competition terms and conditions [PDF, 136 KB]

To find out more about the redefinition of the SI units, come along to one of our SI roadshow events that are taking place throughout New Zealand. The winner will be announced at the World Metrology Day event in Wellington on the 20th May 2019.

REGISTER NOW at your nearest event:

Dunedin(external link) Thursday 21st March

Christchurch(external link) Thursday 28th March

Hamilton(external link) Thursday 4th April

Auckland Thursday 9th May (opening soon)

Wellington Monday 20th May (opening soon)



New Zealand’s primary kilogram was not actually used in the production of this video and sits safe and sound in a vault at the Measurement Standards Laboratory. No scientists’ brains were used in the production of any measurement uncertainty budgets for the results obtained during the promotional stunt. These results should not be relied upon for anything other than the purpose for which they were obtained.