Social Reach Calculator
Organic reach from followers and a reach rate, with the hours priced into an effective CPM and set against what the same impressions would cost to buy.
Followers 18,500
Reach a post 962, 5.2% of them
Posts 5.0 a week, 21.7 a month
A month of posting
impressions 20,899
as a multiple of the follower count 1.13×
which is not that many people: the same core group sees most of the posts, so this counts deliveries rather than humans
engagements 376 at 1.8% of reach
What it costs
hours 32.6 a month at 1.50 hours a post
at $45.00
cost a month $1,466.44
cost a post $67.50
effective CPM $70.17 a thousand impressions
cost an engagement $3.8981
Against buying the same impressions
paid CPM $9.00
what these impressions would cost $188.10
what they cost you $1,466.44
the difference $1,278.34
ratio 7.8× the paid rate
reading the impressions alone cost more to earn than to buy, so the case for organic has to rest on what a bought impression does not do
What the hours would buy instead
impressions at the paid CPM 162,938
against organic 20,899
If the reach rate moves
at 1% 4,019 impressions a month, $364.86 CPM
at 2% 8,038 impressions a month, $182.43 CPM
at 5% 20,096 impressions a month, $72.97 CPM
at 10% 40,191 impressions a month, $36.49 CPM
Followers you would need
for 41,799 impressions 37,000 followers at this reach rate
for 104,497 impressions 92,500 followers at this reach rate
20,899 impressions a month cost $1,466.44 in time, which is $70.17 a
thousand. Organic reach is free of media cost and nothing else, and the
hours are usually the largest line in the channel.
Reach rate is the number to watch and the one nobody controls. Organic
reach on the major platforms has fallen for over a decade, and a
strategy built on the rate you had two years ago is planning against
inventory that no longer exists.
Impressions are not people. The same core group sees most of what you
post, so a monthly impression count several times the follower count is
normal and does not mean you reached everybody several times: it means
you reached the same engaged minority repeatedly.
The paid comparison is deliberately unfair to organic, because a bought
impression is not the same thing. Organic reach lands on people who
chose to follow you, it builds an audience you keep rather than rent,
and the post is still there next year. The comparison is there to make
the trade visible, not to settle it.
Posting more does not raise reach proportionally. Feeds limit how often
one account appears to the same person, and the marginal post competes
with your own previous post, so doubling the frequency usually buys much
less than double the reach.
Engagement rate is measured against reach here, not against followers.
Both conventions exist, the second produces a much smaller number on an
account with poor reach, and comparing two accounts on different
conventions compares arithmetic rather than performance.
None of this measures whether the audience buys anything. Reach,
impressions and engagements are all upstream of revenue, and a channel
can improve all three for a year while selling nothing.
Output is valid and updates as you type.
Fix the highlighted fields to update the output.
Organic reach is free of media cost and nothing else. A post takes time to make, and the time is the expensive part: five posts a week at an hour and a half each is about 33 hours a month, which is a cost whoever pays it.
Put the hours against the impressions and you get an effective CPM. On the example it is $70.17 a thousand, against $9 to buy the same impressions. That comparison is the single most useful line a social report can contain, and almost no social report contains it.
It is also deliberately unfair to organic, and the tool says so. A bought impression is not the same thing: organic reach lands on people who chose to follow you, it builds an audience you own rather than rent, and the post is still there next year. The point is to make the trade visible rather than to settle it.
How to use
- Put in the follower count and your own reach rate from the last month, not a published average.
- Put in the posting frequency and the hours a post, including strategy, writing, filming and editing.
- Add a paid CPM to see what the same impressions would cost to buy.
Example
18,500 followers reaching 5.2 percent a post, five posts a week, 1.5 hours each at $45:
Reach a post 962, 5.2% of them
Posts 5.0 a week, 21.7 a month
A month of posting
impressions 20,899
as a multiple of the follower count 1.13×
which is not that many people: the same core group sees most of the posts
engagements 376 at 1.8% of reach
What it costs
hours 32.6 a month at 1.50 hours a post
cost a month $1,466.44
cost a post $67.50
effective CPM $70.17 a thousand impressions
cost an engagement $3.8981
Against buying the same impressions
paid CPM $9.00
what these impressions would cost $188.10
what they cost you $1,466.44
ratio 7.8× the paid rate
What the hours would buy instead
impressions at the paid CPM 162,938
against organic 20,899
If the reach rate moves
at 2% 8,038 impressions a month, $182.43 CPM
at 10% 40,191 impressions a month, $36.49 CPMThe last table is the reason reach rate is worth defending. Everything about the cost of the channel is downstream of it.
Pitfalls
Impressions are not people. The same core group sees most of what you post, so a monthly impression count above the follower count is normal and does not mean you reached everybody. It counts deliveries.
Reach rate is the number nobody controls. It has fallen on every major platform for over a decade. A strategy built on the rate you had two years ago is planning against inventory that no longer exists.
Posting more does not raise reach proportionally. Feeds limit how often one account appears to the same person, so the marginal post competes with your own previous post. Doubling the frequency usually buys far less than double the reach and always doubles the hours.
The hours are the cost, and they are usually unpriced. If nobody has costed them, the channel has never been evaluated, only admired.
Engagement rate has two conventions. Against reach, as here, and against followers. On an account with poor reach the second is much smaller, and comparing two accounts on different conventions compares arithmetic rather than performance.
The paid comparison is not the whole case. Owned audience, warmer attention, search visibility and content that keeps working are all real and none of them are in a CPM. Use the comparison to force the argument, not to end it.
None of this measures whether the audience buys. Reach, impressions and engagements all sit upstream of revenue. A channel can improve all three for a year while selling nothing.
Compatibility
Arithmetic in the browser: nothing is uploaded and nothing is stored.
A month is 4.345 weeks, so a weekly posting cadence converts to a monthly figure without drifting. Impressions are reach a post multiplied by posts a month, which is why the output labels them deliveries rather than people: the tool makes no attempt to deduplicate, and says so rather than quietly implying unique reach.
The effective CPM is the monthly hours cost divided by thousands of impressions, so it moves with the reach rate and the hourly rate together, and the sensitivity table shows the reach rate’s effect on both numbers at once.
Setting the paid CPM to zero removes the comparison sections, and setting the hours to zero removes the cost section rather than printing a zero CPM that would read as free.