DAX - cumulative % small difference. Rounding?

[Youri98]

Hi!

I've got a simple DAX showing the % per month. Dividing the new products / total per month. The % for each month is correct. Now, I would like to show a line in my chart, showing the cumulative values, but this differences slightly. How do I fix this? If I select April it says 3,07%, but if I select January till May it jumps from 1,70% to 4,74% in April (3,04% difference). Is this because of rounding? 

Thanks in advance! 

Month	% per month	New per month	Total per month	Cumulative %
2025-january	0,44%	17	3896	0,44%
2025-february	0,54%	21	3892	0,98%
2025-march	0,72%	28	3881	1,70%
2025-april	3,07%	121	3941	4,74%
2025-may	0,23%	9	3941	4,97%
Total	5,01%	196	3910,2	5,01%

[v-hashadapu]

Hi @Youri98 , Please let us know if your issue is solved. If it is, consider marking the answer that helped 'Accept as Solution', so others with similar queries can find it easily. If not, please share the details.
Thank you.

[v-hashadapu]

Hi @Youri98 , Please let us know if your issue is solved. If it is, consider marking the answer that helped 'Accept as Solution', so others with similar queries can find it easily. If not, please share the details.
Thank you.

[v-hashadapu]

Hi @Youri98 , Thank you for reaching out to the Microsoft Community Forum.

Please let us know if your issue is solved. If it is, consider marking the answers that helped 'Accept as Solution', so others with similar queries can find them easily. If not, please share the details.
Thank you.

[Sahir_Maharaj]

Hello @Youri98,

Can you please try this approach:

Cumulative % True = 
DIVIDE(
    CALCULATE(SUM('Table'[New per month]), FILTER(ALLSELECTED('Table'), 'Table'[Month] <= MAX('Table'[Month]))),
    CALCULATE(SUM('Table'[Total per month]), FILTER(ALLSELECTED('Table'), 'Table'[Month] <= MAX('Table'[Month])))
)

[bhanu_gautam · Accepted solution]

@Youri98 The discrepancy you're seeing in the cumulative percentage values is likely due to the way cumulative percentages are calculated and possibly due to rounding differences

Calculate the cumulative total of new products:

DAX
CumulativeNewProducts =
CALCULATE(
SUM('Table'[New per month]),
FILTER(
ALLSELECTED('Table'),
'Table'[Month] <= MAX('Table'[Month])
)
)

Calculate the cumulative total of all products:

DAX
CumulativeTotalProducts =
CALCULATE(
SUM('Table'[Total per month]),
FILTER(
ALLSELECTED('Table'),
'Table'[Month] <= MAX('Table'[Month])
)
)

Calculate the cumulative percentage:

DAX
CumulativePercentage =
DIVIDE(
[CumulativeNewProducts],
[CumulativeTotalProducts],
0
)