Free tools for archers

I have put together some tools: calculators for your setup and your group, a quiz, a tap target, printable sheets for marking your arrows and for taking to the range, and the tools that tell you whether a score has changed or it is just chance. They are free, and they stay free.

Draw length and arrow length calculator

From your arm span it works out your estimated draw length and the right arrow length.

I use the industry-standard method, the same starting point any coach uses: a reliable estimate to begin with, to be refined on the range. If you already know your draw length in inches, enter it and get the arrow length right away.

Fingertip to fingertip, in cm

Optional, in inches. If entered, this takes priority

What about spine?

Spine cannot be worked out from body measurements. It depends on your actual draw weight, your arrow length and your point weight, and you choose it from the manufacturer's chart, which differs from one shaft model to the next; you then fine-tune it on the range with a bare shaft test.

Open the official Easton selector

Open the calculator page, with the draw length to arrow length chart

Quiz: where are you losing points?

Seven questions about your shot, one at a time, and at the end the area it makes sense to start from.

The result comes from how you perceive your own shot: it shows you where to begin, but it does not replace a measurement.

At the end of a long session, what do you notice most often?

When you reach anchor, your bow arm…

At the moment of release, what happens?

Your aim, at full draw…

From one arrow to the next, your execution…

In competition, compared with training…

When you miss, how do your groups "miss"?

Group simulator

Move four variables and watch a group of twelve arrows tighten, or open up.

This is what I measure: every variable you stabilise removes dispersion, and dispersion is what separates a good score from a poor one.

Target with arrow grouping
45%
45%
45%
45%
Average score
7.3 / 10
Dispersion
±18.9 cm
Grouping
loose

The shape of your group

Three typical group shapes on the target, and where it makes sense to start looking.

A tight group low-left is not the same as a vertical scatter. Each shape narrows the field to a family of causes, but it does not hand you the answer: from there you check one variable at a time.

  • Twelve arrows scattered around the centre of the target

    Centred scatter

    Good centroid, wide group · 12 arrows

    What it may indicate. The centre of the group is where it should be, so aiming is not the issue: repeatability is. It is usually several variables adding up, and the group often opens up with fatigue at the end of a session or when the routine slips.

  • Twelve arrows in a tight group low and to the left of the centre

    Tight offset

    Tight group, off-centre · 12 arrows

    What it may indicate. The shot is repeatable and the group simply points a little away from the centre: it is usually a matter of aim or tuning, and takes minutes to fix. If the offset appears suddenly, without any change in your shot, check the equipment first.

  • Twelve arrows lined up vertically, from above to below the centre

    Vertical

    Scatter on the vertical axis · 12 arrows

    What it may indicate. From one arrow to the next something changes that raises or drops the shot: usually draw length, anchor or release timing, followed by back tension through the finish and the nocking point.

Read the full breakdown: why do my arrows go left, right, high or low

How many points it takes to show you have improved

Two identical archers, over 72 arrows, end up five points apart on average by pure chance. The calculator tells you what a ranking gap is worth and how many rounds it takes before and after a technical change to say that it worked, with the working explained step by step.

Open the score gap calculator

Did I really improve?

You have two rounds and two different scores. From the ring counts the tool works out your floor, how much your total moves by pure chance, and tells you whether the gap is a difference, a match, or something those rounds cannot settle yet.

Open "Did I really improve?"

The change detector

After a technical change, the detector follows your rounds one at a time, in the order you shot them, and shows the first one at which the improvement, or the decline, can no longer be put down to the normal fluctuation of your total.

Open the change detector

The floor of your score

A 72-arrow total changes from one round to the next even when your shooting stays the same. The calculator tells you by how much, at your level or from your own totals, how large a difference you need between two blocks of rounds and how many rounds it takes to confirm it.

Open the floor calculator

How big your group is

From the ring counts of a round, without marking where each arrow landed, the calculator works out the size of your group in millimetres, the diameter that holds nine arrows in ten and the share of arrows that left the group.

Open the group size calculator

The tap target

You mark each arrow with a finger, in shooting order, on a 122 cm face drawn to scale. Out come the coordinates in millimetres, the score, the centre and shape of the group, and a CSV file to keep; everything stays on your device.

Open the tap target

The plotting sheet

When there is no phone on the range, the 122 cm face prints to scale on an A4 sheet and each arrow is marked in pencil with its order number. A 100 mm bar tells you whether the print has come out at the right scale.

Open the plotting sheet

The assessment sheet

An A4 sheet to take to the range for assessing an archer with pen and paper: reference tables by level, the sum that tells you whether a change is bigger than chance, the test for the direction of the error and space for three training priorities.

Open the assessment sheet

The field cards

One card per domain, from technique to health, that prints on a single A4 sheet: the terms that recur in the studies, with a one-line definition, and the registry claims that are currently corroborated, contested, contradicted or refuted, each with its status. The address and the date are printed at the bottom, because statuses change.

Open the field cards

These tools start from your measurements and from how your shot feels to you. When you want to see it in the data, with timing, stability and hold, get in touch: I read every message and reply myself.

Get in touch